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  • Calling 32 bit unmanaged dlls from C# randomly failing

    - by Bert
    Hi, I'm having an issue when calling 32 bit delphi dll's from c# web site. The code generally runs fine, but occasionally I get an error Unable to load DLL '': The specified module could not be found. (Exception from HRESULT: 0x8007007E). This issue persists until I recycle the app pool for the site, and then it works fine again. On the same server, there is also a web service that is calling the same set of dlls. This web service doesn't seem to have the same issue that the web site has. Both applications are using .net framework 3.5, separate app pools on IIS. Here is the code I'm using to wrap the dlls: public sealed class Mapper { static Mapper instance = null; [DllImport("kernel32.dll")] private static extern bool SetDllDirectory(string lpPathName); private Mapper() { SetDllDirectory(ConfigManager.Path); } public static Mapper Instance { get { if (instance == null) { instance = new Mapper(); } return instance; } } public int Foo(string bar, ref double val) { return Loader.Foo(bar, ref val); } } public static class Loader { [DllImport("some.dll", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Unicode, EntryPoint = "foo")] public static extern int Foo(string bar, ref double val); } Then I call it like this: double val = 0.0; Mapper.Instance.Foo("bar", ref val); Any ideas as to why it would "randomly" Unable to load DLL '': The specified module could not be found. (Exception from HRESULT: 0x8007007E). The other problem is that I haven't been able to replicate the issue in the development environment. I thought that due to 2 applications calling the same dlls, that there could be some locks occurring. To replicate this, I created an app that spawned multiple threads and repeatedly called the 32bit dlls, and then used the web site to call these same dlls. I still couldn't replicate the issue. Some possible fixes that I can think of: Wrap the 32 bit dlls in web service (because the webservice doesn't seem to suffer from the same problem). But this may be worthless if it turns out that the web service also fails. Set up state server for the session state and periodically recycle the app pool for the site.This isn't fixing the problem, only avoiding it. Wrap the dll's in exe, and call that exe. Then I shouldn't get the same issue. But this also seems like a hacky solution. Implement the mapper class differently ? But how else should I be doing the call? The other draw back is that other applications are using this mapper, so I'd need to change there code too. Thanks

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  • Optimising movement on hex grid

    - by Mloren
    I am making a turn based hex-grid game. The player selects units and moves them across the hex grid. Each tile in the grid is of a particular terrain type (eg desert, hills, mountains, etc) and each unit type has different abilities when it comes to moving over the terrain (e.g. some can move over mountains easily, some with difficulty and some not at all). Each unit has a movement value and each tile takes a certain amount of movement based on its terrain type and the unit type. E.g it costs a tank 1 to move over desert, 4 over swamp and cant move at all over mountains. Where as a flying unit moves over everything at a cost of 1. The issue I have is that when a unit is selected, I want to highlight an area around it showing where it can move, this means working out all the possible paths through the surrounding hexes, how much movement each path will take and lighting up the tiles based on that information. I got this working with a recursive function and found it took too long to calculate, I moved the function into a thread so that it didn't block the game but still it takes around 2 seconds for the thread to calculate the moveable area for a unit with a move of 8. Its over a million recursions which obviously is problematic. I'm wondering if anyone has an clever ideas on how I can optimize this problem. Here's the recursive function I'm currently using (its C# btw): private void CalcMoveGridRecursive(int nCenterIndex, int nMoveRemaining) { //List of the 6 tiles adjacent to the center tile int[] anAdjacentTiles = m_ThreadData.m_aHexData[nCenterIndex].m_anAdjacentTiles; foreach(int tileIndex in anAdjacentTiles) { //make sure this adjacent tile exists if(tileIndex == -1) continue; //How much would it cost the unit to move onto this adjacent tile int nMoveCost = m_ThreadData.m_anTerrainMoveCost[(int)m_ThreadData.m_aHexData[tileIndex].m_eTileType]; if(nMoveCost != -1 && nMoveCost <= nMoveRemaining) { //Make sure the adjacent tile isnt already in our list. if(!m_ThreadData.m_lPassableTiles.Contains(tileIndex)) m_ThreadData.m_lPassableTiles.Add(tileIndex); //Now check the 6 tiles surrounding the adjacent tile we just checked (it becomes the new center). CalcMoveGridRecursive(tileIndex, nMoveRemaining - nMoveCost); } } } At the end of the recursion, m_lPassableTiles contains a list of the indexes of all the tiles that the unit can possibly reach and they are made to glow. This all works, it just takes too long. Does anyone know a better approach to this?

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  • Why do I get rows of zeros in my 2D fft?

    - by Nicholas Pringle
    I am trying to replicate the results from a paper. "Two-dimensional Fourier Transform (2D-FT) in space and time along sections of constant latitude (east-west) and longitude (north-south) were used to characterize the spectrum of the simulated flux variability south of 40degS." - Lenton et al(2006) The figures published show "the log of the variance of the 2D-FT". I have tried to create an array consisting of the seasonal cycle of similar data as well as the noise. I have defined the noise as the original array minus the signal array. Here is the code that I used to plot the 2D-FT of the signal array averaged in latitude: import numpy as np from numpy import ma from matplotlib import pyplot as plt from Scientific.IO.NetCDF import NetCDFFile ### input directory indir = '/home/nicholas/data/' ### get the flux data which is in ### [time(5day ave for 10 years),latitude,longitude] nc = NetCDFFile(indir + 'CFLX_2000_2009.nc','r') cflux_southern_ocean = nc.variables['Cflx'][:,10:50,:] cflux_southern_ocean = ma.masked_values(cflux_southern_ocean,1e+20) # mask land nc.close() cflux = cflux_southern_ocean*1e08 # change units of data from mmol/m^2/s ### create an array that consists of the seasonal signal fro each pixel year_stack = np.split(cflux, 10, axis=0) year_stack = np.array(year_stack) signal_array = np.tile(np.mean(year_stack, axis=0), (10, 1, 1)) signal_array = ma.masked_where(signal_array > 1e20, signal_array) # need to mask ### average the array over latitude(or longitude) signal_time_lon = ma.mean(signal_array, axis=1) ### do a 2D Fourier Transform of the time/space image ft = np.fft.fft2(signal_time_lon) mgft = np.abs(ft) ps = mgft**2 log_ps = np.log(mgft) log_mgft= np.log(mgft) Every second row of the ft consists completely of zeros. Why is this? Would it be acceptable to add a randomly small number to the signal to avoid this. signal_time_lon = signal_time_lon + np.random.randint(0,9,size=(730, 182))*1e-05 EDIT: Adding images and clarify meaning The output of rfft2 still appears to be a complex array. Using fftshift shifts the edges of the image to the centre; I still have a power spectrum regardless. I expect that the reason that I get rows of zeros is that I have re-created the timeseries for each pixel. The ft[0, 0] pixel contains the mean of the signal. So the ft[1, 0] corresponds to a sinusoid with one cycle over the entire signal in the rows of the starting image. Here are is the starting image using following code: plt.pcolormesh(signal_time_lon); plt.colorbar(); plt.axis('tight') Here is result using following code: ft = np.fft.rfft2(signal_time_lon) mgft = np.abs(ft) ps = mgft**2 log_ps = np.log1p(mgft) plt.pcolormesh(log_ps); plt.colorbar(); plt.axis('tight') It may not be clear in the image but it is only every second row that contains completely zeros. Every tenth pixel (log_ps[10, 0]) is a high value. The other pixels (log_ps[2, 0], log_ps[4, 0] etc) have very low values.

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  • Composite Views and View Controllers

    - by BillyK
    Hi, I'm somewhat new to Android and am in the process of designing an application with a couple fairly complex views. One of the views is intended to involve a complex view displaying information associated with model objects and segregated into several different views; the navigation of which is meant to be achieved using sliding effects (i.e. sliding one's finger across the screen to traverse from one screen to the next, etc). The view itself will be used to host multiple sets of views for varying types of model objects, but with a general structure that is reused between them all. As a rough example, the view might come up to display information about a person (the model object), displaying several details views: a view for general information, a view displaying a list of hobbies, and a view displaying a list of other individuals associated with their social network. The same general view, when given a model object representing a particular car would give several different views: A general view with details, A view containing photo images for that vehicle, a view representing locations which it could be purchased from, and a view providing a list of related cars. (NOTE: This is not the real data involved, but is representative of the general intent for the view). The subviews will NOT cover the entire screen real-estate and other features within the view should be both visible and able to be interacted with by the user. The idea here is that there is a general view structure that is reusable and which will manage a set of subviews dynamically generated based upon the type of model object handed to the view. I'm trying to determine the appropriate way to leverage the Android framework in order to best achieve this without violating the integrity of the framework. Basically, I'm trying to determine how to componentize this larger view into reusable units (i.e. general view, model-specific sub-view controllers, and individual detail views). To be more specific, I'm trying to determine if this view is best designed as a composite of several custom View classes or a composite of several Activity classes. I've seen several examples of custom composite views, but they typically are used to compose simple views without complex controllers and without attention to the general Activity lifecycle (i.e. storing and retrieving data related to the model objects, as appropriate). On the other hand, the only real example I've seen regarding a view comprised of a composite of Activities is the TabActivity itself, and that isn't customizable in the fashion that would be necessary for this. Does anyone have any suggestions as to the appropriate way to structure my view to achieve the application framework I'm looking for? Views? Activities? Something else? Any guidance would be appreciated. Thanks in advance.

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  • If Then Statement Condition Being Ignored With Optimisations On

    - by Matma
    I think im going mad but can some show me what im missing, it must be some stupidly simple i just cant see the wood for the trees. BOTH side of this if then else statement are being executed? Ive tried commenting out the true side and moving the condition to a seperate variable with the same result. However if i explicitly set the condition to 1=0 or 1=1 then the if then statement is operating as i would expect. i.e. only executing one side of the equation... The only time ive seen this sort of thing is when the compiler has crashed and is no longer compiling (without visible indication that its not) but ive restarted studio with the same results, ive cleaned the solution, built and rebuilt with no change? please show me the stupid mistake im making using vs2005 if it matters. Dim dset As DataSet = New DataSet If (CboCustomers.SelectedValue IsNot Nothing) AndAlso (CboCustomers.SelectedValue <> "") Then Dim Sql As String = "Select sal.SalesOrderNo As SalesOrder,cus.CustomerName,has.SerialNo, convert(varchar,sal.Dateofpurchase,103) as Date from [dbo].[Customer_Table] as cus " & _ " inner join [dbo].[Hasp_table] as has on has.CustomerID=cus.CustomerTag " & _ " inner join [dbo].[salesorder_table] as sal On sal.Hasp_ID =has.Hasp_ID Where cus.CustomerTag = '" & CboCustomers.SelectedValue.ToString & "'" Dim dap As SqlDataAdapter = New SqlDataAdapter(Sql, FormConnection) dap.Fill(dset, "dbo.Customer_Table") DGCustomer.DataSource = dset.Tables("dbo.Customer_Table") Else Dim erm As String = "wtf" End If EDIT: i have found that this is something to do with the release config settings im using, i guesing its the optimisations bit. does anyone know of any utils/addons for vs that show if a line has been optimised out. delphi, my former language showed blue dots in the left margin to show that it was a compiled line, no dot meaning it wasnt compiled in, is there anything like that for vs? alternatively can someone explain how optimisations would affect this simple if statement causeing it to run both sides? EDIT2: using this thread as possible causes/solutions : http://stackoverflow.com/questions/2135509/bug-only-occurring-when-compile-optimization-enabled. It does the same with release = optimisations on, x86, x64 and AnyCPU Goes away with optimisations off. Im using V2005 on a x64 win7 machine, if that matters. Thanks

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  • Flipping OpenGL texture

    - by Mk12
    When I load textures from images normally, they are upside down because of OpenGL's coordinate system. What would be the best way to flip them? glScalef(1.0f, -1.0f, 1.0f); vertically flipping the image files manually (in Photoshop) flipping them programatically after loading them (I don't know how) This is the method I'm using to load png textures, in my Utilities.m file (Objective-C): + (GLuint)loadPngTexture:(NSString *)name { CFURLRef textureURL = CFBundleCopyResourceURL( CFBundleGetMainBundle(), (CFStringRef)name, CFSTR("png"), CFSTR("Textures")); NSAssert(textureURL, @"Texture name invalid"); CGImageSourceRef imageSource = CGImageSourceCreateWithURL(textureURL, NULL); NSAssert(imageSource, @"Invalid Image Path."); NSAssert((CGImageSourceGetCount(imageSource) > 0), @"No Image in Image Source."); CFRelease(textureURL); CGImageRef image = CGImageSourceCreateImageAtIndex(imageSource, 0, NULL); NSAssert(image, @"Image not created."); CFRelease(imageSource); NSUInteger width = CGImageGetWidth(image); NSUInteger height = CGImageGetHeight(image); void *data = malloc(width * height * 4); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); NSAssert(colorSpace, @"Colorspace not created."); CGContextRef context = CGBitmapContextCreate( data, width, height, 8, width * 4, colorSpace, kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host); NSAssert(context, @"Context not created."); CGColorSpaceRelease(colorSpace); CGContextDrawImage(context, CGRectMake(0, 0, width, height), image); CGImageRelease(image); CGContextRelease(context); GLuint textureId; glGenTextures(1, &textureId); glBindTexture(GL_TEXTURE_2D, textureId); glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS, GL_TRUE); glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, data); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE_SGIS); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE_SGIS); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); free(data); return textureId; } Also, another thing I was wondering about: If I made a simple 2d game, with pixels mapped to units, would it be alright to set it up so that the origin is in the top-left corner, or would I run in to problems with other things (e.g. text rendering)? Thanks.

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  • Symfony2 Entity to array

    - by Adriano Pedro
    I'm trying to migrate my flat php project to Symfony2, but its coming to be very hard. For instance, I have a table of Products specification that have several specifications and are distinguishables by its "cat" attribute in that Extraspecs DB table. Therefore I've created a Entity for that table and want to make an array of just the specifications with "cat" = 0... I supose the code is this one.. right? $typeavailable = $this->getDoctrine() ->getRepository('LabsCatalogBundle:ProductExtraspecsSpecs') ->findBy(array('cat' => '0')); Now how can i put this in an array to work with a form like this?: form = $this ->createFormBuilder($product) ->add('specs', 'choice', array('choices' => $typeavailableArray), 'multiple' => true) Thank you in advance :) # Thank you all.. But now I've came across with another problem.. In fact i'm building a form from an existing object: $form = $this ->createFormBuilder($product) ->add('name', 'text') ->add('genspec', 'choice', array('choices' => array('0' => 'None', '1' => 'General', '2' => 'Specific'))) ->add('isReg', 'choice', array('choices' => array('0' => 'Material', '1' => 'Reagent', '2' => 'Antibody', '3' => 'Growth Factors', '4' => 'Rodents', '5' => 'Lagomorphs'))) So.. in that case my current value is named "extraspecs", so i've added this like: ->add('extraspecs', 'entity', array( 'label' => 'desc', 'empty_value' => ' --- ', 'class' => 'LabsCatalogBundle:ProductExtraspecsSpecs', 'property' => 'specsid', 'query_builder' => function(EntityRepository $er) { return $er ->createQueryBuilder('e'); But "extraspecs" come from a relationship of oneToMany where every product has several extraspecs... Here is the ORM: Labs\CatalogBundle\Entity\Product: type: entity table: orders__regmat id: id: type: integer generator: { strategy: AUTO } fields: name: type: string length: 100 catnumber: type: string scale: 100 brand: type: integer scale: 10 company: type: integer scale: 10 size: type: decimal scale: 10 units: type: integer scale: 10 price: type: decimal scale: 10 reqcert: type: integer scale: 1 isReg: type: integer scale: 1 genspec: type: integer scale: 1 oneToMany: extraspecs: targetEntity: ProductExtraspecs mappedBy: product Labs\CatalogBundle\Entity\ProductExtraspecs: type: entity table: orders__regmat__extraspecs fields: extraspecid: id: true type: integer unsigned: false nullable: false generator: strategy: IDENTITY regmatid: type: integer scale: 11 spec: type: integer scale: 11 attrib: type: string length: 20 value: type: string length: 200 lifecycleCallbacks: { } manyToOne: product: targetEntity: Product inversedBy: extraspecs joinColumn: name: regmatid referencedColumnName: id HOw should I do this? Thank you!!!

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  • Dependency Injection: I don't get where to start!

    - by Andy
    I have several articles about Dependency Injection, and I can see the benefits, especially when it comes to unit testing. The units can me loosely coupled, and mocking of dependencies can be made. The trouble is - I just don't get where to start. Consider this snippet below of (much edited for the purpose of this post) code that I have. I am instantiating a Plc object from the main form, and passing in a communications mode via the Connect method. In it's present form it becomes hard to test, because I can't isolate the Plc from the CommsChannel to unit test it. (Can I?) The class depends on using a CommsChannel object, but I am only passing in a mode that is used to create this channel within the Plc itself. To use dependancy injection, I should really pass in an already created CommsChannel (via an 'ICommsChannel' interface perhaps) to the Connect method, or maybe via the Plc constructor. Is that right? But then that would mean creating the CommsChannel in my main form first, and this doesn't seem right either, because it feels like everything will come back to the base layer of the main form, where everything begins. Somehow it feels like I am missing a crucial piece of the puzzle. Where do you start? You have to create an instance of something somewhere, but I'm struggling to understand where that should be. public class Plc() { public bool Connect(CommsMode commsMode) { bool success = false; // Create new comms channel. this._commsChannel = this.GetCommsChannel(commsMode); // Attempt connection success = this._commsChannel.Connect(); return this._connected; } private CommsChannel GetCommsChannel(CommsMode mode) { CommsChannel channel; switch (mode) { case CommsMode.RS232: channel = new SerialCommsChannel( SerialCommsSettings.Default.ComPort, SerialCommsSettings.Default.BaudRate, SerialCommsSettings.Default.DataBits, SerialCommsSettings.Default.Parity, SerialCommsSettings.Default.StopBits); break; case CommsMode.Tcp: channel = new TcpCommsChannel( TCPCommsSettings.Default.IP_Address, TCPCommsSettings.Default.Port); break; default: // Throw unknown comms channel exception. } return channel; } }

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  • How to define and work with an array of bits in C?

    - by Eddy
    I want to create a very large array on which I write '0's and '1's. I'm trying to simulate a physical process called random sequential adsorption, where units of length 2, dimers, are deposited onto an n-dimensional lattice at a random location, without overlapping each other. The process stops when there is no more room left on the lattice for depositing more dimers (lattice is jammed). Initially I start with a lattice of zeroes, and the dimers are represented by a pair of '1's. As each dimer is deposited, the site on the left of the dimer is blocked, due to the fact that the dimers cannot overlap. So I simulate this process by depositing a triple of '1's on the lattice. I need to repeat the entire simulation a large number of times and then work out the average coverage %. I've already done this using an array of chars for 1D and 2D lattices. At the moment I'm trying to make the code as efficient as possible, before working on the 3D problem and more complicated generalisations. This is basically what the code looks like in 1D, simplified: int main() { /* Define lattice */ array = (char*)malloc(N * sizeof(char)); total_c = 0; /* Carry out RSA multiple times */ for (i = 0; i < 1000; i++) rand_seq_ads(); /* Calculate average coverage efficiency at jamming */ printf("coverage efficiency = %lf", total_c/1000); return 0; } void rand_seq_ads() { /* Initialise array, initial conditions */ memset(a, 0, N * sizeof(char)); available_sites = N; count = 0; /* While the lattice still has enough room... */ while(available_sites != 0) { /* Generate random site location */ x = rand(); /* Deposit dimer (if site is available) */ if(array[x] == 0) { array[x] = 1; array[x+1] = 1; count += 1; available_sites += -2; } /* Mark site left of dimer as unavailable (if its empty) */ if(array[x-1] == 0) { array[x-1] = 1; available_sites += -1; } } /* Calculate coverage %, and add to total */ c = count/N total_c += c; } For the actual project I'm doing, it involves not just dimers but trimers, quadrimers, and all sorts of shapes and sizes (for 2D and 3D). I was hoping that I would be able to work with individual bits instead of bytes, but I've been reading around and as far as I can tell you can only change 1 byte at a time, so either I need to do some complicated indexing or there is a simpler way to do it? Thanks for your answers

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  • OpenGL Coordinate system confusion

    - by user146780
    Maybe I set up GLUT wrong. Basically I want verticies to be reletive to their size in pixels. Ex:right now if I create a hexagon, it hakes up the whole screen even though the units are 6. #include <iostream> #include <stdlib.h> //Needed for "exit" function #include <cmath> //Include OpenGL header files, so that we can use OpenGL #ifdef __APPLE__ #include <OpenGL/OpenGL.h> #include <GLUT/glut.h> #else #include <GL/glut.h> #endif using namespace std; //Called when a key is pressed void handleKeypress(unsigned char key, //The key that was pressed int x, int y) { //The current mouse coordinates switch (key) { case 27: //Escape key exit(0); //Exit the program } } //Initializes 3D rendering void initRendering() { //Makes 3D drawing work when something is in front of something else glEnable(GL_DEPTH_TEST); } //Called when the window is resized void handleResize(int w, int h) { //Tell OpenGL how to convert from coordinates to pixel values glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); //Switch to setting the camera perspective //Set the camera perspective glLoadIdentity(); //Reset the camera gluPerspective(45.0, //The camera angle (double)w / (double)h, //The width-to-height ratio 1.0, //The near z clipping coordinate 200.0); //The far z clipping coordinate } //Draws the 3D scene void drawScene() { //Clear information from last draw glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); //Reset the drawing perspective glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); glBegin(GL_POLYGON); //Begin quadrilateral coordinates //Trapezoid glColor3f(255,0,0); for(int i = 0; i < 6; ++i) { glVertex2d(sin(i/6.0*2* 3.1415), cos(i/6.0*2* 3.1415)); } glEnd(); //End quadrilateral coordinates glutSwapBuffers(); //Send the 3D scene to the screen } int main(int argc, char** argv) { //Initialize GLUT glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH); glutInitWindowSize(400, 400); //Set the window size //Create the window glutCreateWindow("Basic Shapes - videotutorialsrock.com"); initRendering(); //Initialize rendering //Set handler functions for drawing, keypresses, and window resizes glutDisplayFunc(drawScene); glutKeyboardFunc(handleKeypress); glutReshapeFunc(handleResize); glutMainLoop(); //Start the main loop. glutMainLoop doesn't return. return 0; //This line is never reached } How can I make it so that a polygon of 0,0 10,0 10,10 0,10 defines a polygon starting at the top left of the screen and is a width and height of 10 pixels? Thanks

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  • ListBox ,ScrollViewer ? CanContentScroll

    - by mrK
    Hi! I have ListBox with ScrollViewer <ScrollViewer Focusable="False" CanContentScroll="True" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Disabled"> <ListBox ItemsSource="{Binding Path=MyItems}" VerticalAlignment="Stretch" Focusable="False"> <ListBox.ItemContainerStyle> <Style TargetType="{x:Type ListBoxItem}"> <Setter Property="OverridesDefaultStyle" Value="true"/> <Setter Property="HorizontalContentAlignment" Value="Stretch"/> <Setter Property="VerticalContentAlignment" Value="Stretch"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="{x:Type ListBoxItem}"> <Border CornerRadius="3,3,3,3"> <Grid> <myControls:MyControl/> </Grid> </Border> </ControlTemplate> </Setter.Value> </Setter> </Style> </ListBox.ItemContainerStyle> <ListBox.Style> <Style TargetType="ListBox"> <Setter Property="SnapsToDevicePixels" Value="true"/> <Setter Property="OverridesDefaultStyle" Value="true"/> <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/> <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/> <Setter Property="ScrollViewer.CanContentScroll" Value="True"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="ListBox"> <ScrollViewer Focusable="False" CanContentScroll="True"> <Border> <StackPanel Margin="2" Orientation="Horizontal" IsItemsHost="True"/> </Border> </ScrollViewer> </ControlTemplate> </Setter.Value> </Setter> </Style> </ListBox.Style> </ListBox> </ScrollViewer> But CanContentScroll="True" does't work. It's still scrolling in physical units. Whats wrong in my code? Thanks!

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  • How does your team work together in a remote setup?

    - by Carl Rosenberger
    Hi, we are a distributed team working on the object database db4o. The way we work: We try to program in pairs only. We use Skype and VNC or SharedView to connect and work together. In our online Tuesday meeting every week (usually about 1 hour) we talk about the tasks done last week we create new pairs for the next week with a random generator so knowledge and friendship distribute evenly we set the priority for any new tasks or bugs that have come in each team picks the tasks it likes to do from the highest prioritized ones. From Tuesday to Wednesday we estimate tasks. We have a unit of work we call "Ideal Developer Session" (IDS), maybe 2 or 3 hours of working together as a pair. It's not perfectly well defined (because we know estimation always is inaccurate) but from our past shared experience we have a common sense of what an IDS is. If we can't estimate a task because it feels too long for a week we break it down into estimatable smaller tasks. During a short meeting on Wednesday we commit to a workload we feel is well doable in a week. We commit to complete. If a team runs out of committed tasks during the week, it can pick new ones from the prioritized queue we have in Jira. When we started working this way, some of us found that remote pair programming takes a lot of energy because you are so focussed. If you pair program for more than 5 or 6 hours per day, you get drained. On the other hand working like this has turned out to be very efficient. The knowledge about our codebase is evenly distributed and we have really learnt lots from eachother. I would be very interested to hear about the experiences from other teams working in a similar way. Things like: How often do you meet? Have you tried different sprint lengths (one week, two week, longer) ? Which tools do you use? Which issue tracker do you use? What do you do about time zone differences? How does it work for you to integrate new people into the team? How many hours do you usually work per week? How does your management interact with the way you are working? Do you get put on a waterfall with hard deadlines? What's your unit of work? What is your normal velocity? (units of work done per week) Programming work should be fun and for us it usually is great fun. I would be happy about any new ideas how to make it even more fun and/or more efficient.

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  • jqgrid modify data returned from ajax call before display in table

    - by user954211
    I have to display some data that I receive from the server as json object like this {"rowndx":"0","rows":"25","rowstotal":"100","rowsdata":[ ["00","DEVICE001","T0_IHOME","1","***","1","10"], ["01","DEVICE002","NO_DEVICE","1","***","1","10"], ["02","DEVICE003","NO_DEVICE","0","***","1","10"], ..... Before displaying the received data in a table I would like to make changes where necessary adding units to the numbers or replacing the numbers with words (eg 0 -OFF 1- ON) To do this I have associated at the ajax option "success" my encoding function. In this case, however, remains always visible the message "Loading ..." and no other action is permitted. I moved my re-encoding procedure to the "complete" ajax option and this time it seems to work. But I did not understand what was my mistake and I do not know if my procedure can work. This is my table ajax configuration url : "devtbl.json", mtype : "POST", datatype : "json", postData : ...... ajaxGridOptions: { type : 'post', contentType: 'application/json', async : false, complete : DEVparse_serverdata, error : function() { alert('Something bad happened. Stopping');}, }, jsonReader : { root : "tablerows", page : "currentpage", total : "totalpages", records : "totalrecords", cell : "", id : "0", userdata : "userdata", repeatitems : true }, and my coding function function DEVparse_serverdata(js , textStatus) { var jsontablereply = {} ; var rowsxpage_int = parseInt(UB.rowsxpage.DEVtable) ; var jsonreply = jQuery.parseJSON(js.responseText) ; jsontablereply.currentpage = "" + (1 + (parseInt(jsonreply.rowndx) / rowsxpage_int)); jsontablereply.totalpages = "" + parseInt((parseInt(jsonreply.rowstotal) + (rowsxpage_int-1)) / rowsxpage_int) ; jsontablereply.totalrecords = jsonreply.rowstotal; jsontablereply.tablerows = [] ; $.each(jsonreply.rowsdata, function(ndx, row) { var rowarray = [] ; rowarray[0] = row[0] ; rowarray[1] = row[1] ; rowarray[2] = row[2] ; rowarray[3] = row[3] ; rowarray[4] = row[4] ; switch (row[2]) { case "NO_DEVICE": rowarray[5] = "***" ; break ; case "T0_IHOME": rowarray[5] = "T=" + row[5] + "°C" ; break ; } jsontablereply.tablerows[ndx] = rowarray ; }) ; // each jQuery("#DEVtbl")[0].addJSONData(jsontablereply); } (I am a beginner with Jquery my coding style is poor)

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  • Big Data – Is Big Data Relevant to me? – Big Data Questionnaires – Guest Post by Vinod Kumar

    - by Pinal Dave
    This guest post is by Vinod Kumar. Vinod Kumar has worked with SQL Server extensively since joining the industry over a decade ago. Working on various versions of SQL Server 7.0, Oracle 7.3 and other database technologies – he now works with the Microsoft Technology Center (MTC) as a Technology Architect. Let us read the blog post in Vinod’s own voice. I think the series from Pinal is a good one for anyone planning to start on Big Data journey from the basics. In my daily customer interactions this buzz of “Big Data” always comes up, I react generally saying – “Sir, do you really have a ‘Big Data’ problem or do you have a big Data problem?” Generally, there is a silence in the air when I ask this question. Data is everywhere in organizations – be it big data, small data, all data and for few it is bad data which is same as no data :). Wow, don’t discount me as someone who opposes “Big Data”, I am a big supporter as much as I am a critic of the abuse of this term by the people. In this post, I wanted to let my mind flow so that you can also think in the direction I want you to see these concepts. In any case, this is not an exhaustive dump of what is in my mind – but you will surely get the drift how I am going to question Big Data terms from customers!!! Is Big Data Relevant to me? Many of my customers talk to me like blank whiteboard with no idea – “why Big Data”. They want to jump into the bandwagon of technology and they want to decipher insights from their unexplored data a.k.a. unstructured data with structured data. So what are these industry scenario’s that come to mind? Here are some of them: Financials Fraud detection: Banks and Credit cards are monitoring your spending habits on real-time basis. Customer Segmentation: applies in every industry from Banking to Retail to Aviation to Utility and others where they deal with end customer who consume their products and services. Customer Sentiment Analysis: Responding to negative brand perception on social or amplify the positive perception. Sales and Marketing Campaign: Understand the impact and get closer to customer delight. Call Center Analysis: attempt to take unstructured voice recordings and analyze them for content and sentiment. Medical Reduce Re-admissions: How to build a proactive follow-up engagements with patients. Patient Monitoring: How to track Inpatient, Out-Patient, Emergency Visits, Intensive Care Units etc. Preventive Care: Disease identification and Risk stratification is a very crucial business function for medical. Claims fraud detection: There is no precise dollars that one can put here, but this is a big thing for the medical field. Retail Customer Sentiment Analysis, Customer Care Centers, Campaign Management. Supply Chain Analysis: Every sensors and RFID data can be tracked for warehouse space optimization. Location based marketing: Based on where a check-in happens retail stores can be optimize their marketing. Telecom Price optimization and Plans, Finding Customer churn, Customer loyalty programs Call Detail Record (CDR) Analysis, Network optimizations, User Location analysis Customer Behavior Analysis Insurance Fraud Detection & Analysis, Pricing based on customer Sentiment Analysis, Loyalty Management Agents Analysis, Customer Value Management This list can go on to other areas like Utility, Manufacturing, Travel, ITES etc. So as you can see, there are obviously interesting use cases for each of these industry verticals. These are just representative list. Where to start? A lot of times I try to quiz customers on a number of dimensions before starting a Big Data conversation. Are you getting the data you need the way you want it and in a timely manner? Can you get in and analyze the data you need? How quickly is IT to respond to your BI Requests? How easily can you get at the data that you need to run your business/department/project? How are you currently measuring your business? Can you get the data you need to react WITHIN THE QUARTER to impact behaviors to meet your numbers or is it always “rear-view mirror?” How are you measuring: The Brand Customer Sentiment Your Competition Your Pricing Your performance Supply Chain Efficiencies Predictive product / service positioning What are your key challenges of driving collaboration across your global business?  What the challenges in innovation? What challenges are you facing in getting more information out of your data? Note: Garbage-in is Garbage-out. Hold good for all reporting / analytics requirements Big Data POCs? A number of customers get into the realm of setting a small team to work on Big Data – well it is a great start from an understanding point of view, but I tend to ask a number of other questions to such customers. Some of these common questions are: To what degree is your advanced analytics (natural language processing, sentiment analysis, predictive analytics and classification) paired with your Big Data’s efforts? Do you have dedicated resources exploring the possibilities of advanced analytics in Big Data for your business line? Do you plan to employ machine learning technology while doing Advanced Analytics? How is Social Media being monitored in your organization? What is your ability to scale in terms of storage and processing power? Do you have a system in place to sort incoming data in near real time by potential value, data quality, and use frequency? Do you use event-driven architecture to manage incoming data? Do you have specialized data services that can accommodate different formats, security, and the management requirements of multiple data sources? Is your organization currently using or considering in-memory analytics? To what degree are you able to correlate data from your Big Data infrastructure with that from your enterprise data warehouse? Have you extended the role of Data Stewards to include ownership of big data components? Do you prioritize data quality based on the source system (that is Facebook/Twitter data has lower quality thresholds than radio frequency identification (RFID) for a tracking system)? Do your retention policies consider the different legal responsibilities for storing Big Data for a specific amount of time? Do Data Scientists work in close collaboration with Data Stewards to ensure data quality? How is access to attributes of Big Data being given out in the organization? Are roles related to Big Data (Advanced Analyst, Data Scientist) clearly defined? How involved is risk management in the Big Data governance process? Is there a set of documented policies regarding Big Data governance? Is there an enforcement mechanism or approach to ensure that policies are followed? Who is the key sponsor for your Big Data governance program? (The CIO is best) Do you have defined policies surrounding the use of social media data for potential employees and customers, as well as the use of customer Geo-location data? How accessible are complex analytic routines to your user base? What is the level of involvement with outside vendors and third parties in regard to the planning and execution of Big Data projects? What programming technologies are utilized by your data warehouse/BI staff when working with Big Data? These are some of the important questions I ask each customer who is actively evaluating Big Data trends for their organizations. These questions give you a sense of direction where to start, what to use, how to secure, how to analyze and more. Sign off Any Big data is analysis is incomplete without a compelling story. The best way to understand this is to watch Hans Rosling – Gapminder (2:17 to 6:06) videos about the third world myths. Don’t get overwhelmed with the Big Data buzz word, the destination to what your data speaks is important. In this blog post, we did not particularly look at any Big Data technologies. This is a set of questionnaire one needs to keep in mind as they embark their journey of Big Data. I did write some of the basics in my blog: Big Data – Big Hype yet Big Opportunity. Do let me know if these questions make sense?  Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • Company Review: Google Products

    Google, Inc offers an array of products and services to all of its end-users. However their search capabilities are the foundation for Google’s current success and their primary business focus. Currently, Google offers over twenty different search applications that allow users to search the internet for books, maps, videos, images, products and much more. Their product decisions have allowed users demands to be met while focusing on the free based model. This allows users to access Google data free of charge and indirectly gives Google a strong competitive advantage of other competitors along with the accuracy of the search results. According to Google, Inc, they offer the following types of searching capabilities: Alerts Get email updates on the topics of your choice Blog Search Find blogs on your favorite topics  Books Search the full text of books  Custom Search Create a customized search experience for your community  Desktop Search and personalize your computer  Dictionary Search for definitions of words and phrases Directory Search the web, organized by topic or category Earth Explore the world from your computer Finance Business info, news and interactive charts GOOG-411 Find and connect for free with businesses from your phone  Images Search for images on the web Maps View maps and directions News Search thousands of news stories Patent Search Search the full text of US Patents Product Search Search for stuff to buy Scholar Search scholarly papers Toolbar Add a search box to your browser Trends Explore past and present search trends Videos Search for videos on the web Web Search Search billions of web pages Web Search Features Find movies, music, stocks, books and more mapping Google’s free based business model is only one way it differentiates itself from its competition. There is also a strong focus on the accuracy of search results and the speed in which they are returned to the end-user. Quality function deployment (QFD) is a structured method used to help connect user needs to the design features of a project proposed to address those needs. This method is particularly useful in accounting for needs that are not easily articulated or precisely defined according to the U. S. Department of Transportation Federal Highway Administration. Due to the fact that QFD is so customer driven Google is always in a constant state of change in attempt to reengineer its search algorithms, and other dependant systems so that end-users requirements are constantly being met. Value engineering is a key example of this, Google is constantly trying to improve all aspects of its products, improve system maintainability, and system interoperability. Bridgefield Group defines value engineering as an organized methodology that identifies and selects the lowest lifecycle cost options in design, materials and processes that achieves the desired level of performance, reliability and customer satisfaction. In addition, it seeks to remove unnecessary costs in the above areas and is often a joint effort with cross-functional internal teams and relevant suppliers. Common issues that appear when developing large scale systems like Google’s search applications include modular design of a product and/or service and providing accurate value analysis. A design approach that adheres to four fundamental tenets of cohesiveness, encapsulation, self-containment, and high binding to design a system component as an independently operable unit subject to change is how the Open System Joint Task Force defines modular design. More specifically M. S. Schmaltz defines modular software design as having a large collection of statements strung together in one partition of in-line code; we segment or divide the statements into logical groups called modules. Each module performs one or two tasks, and then passes control to another module. By breaking up the code into "bite-sized chunks", so to speak, we are able to better control the flow of data and control. This is especially true in large software systems. Value analysis is a process to evaluate products and services based on effectiveness, safety, and cost. Value analysis involves assessing the quality as well as the cost of a product or service as defined by the Healthcare Financial Management Association.  “Operations Management deals with the design and management of products, processes, services and supply chains. It considers the acquisition, development, and utilization of resources that firms need to deliver the goods and services their clients want.” (MIT,2010) Google, Inc encourages an open environment between all employees, also known as Googlers. This is reinforced by a cross-section team or cross-functional teams comprised from multiple departments assigned to every project so that every department like marketing, finance, and quality assurance has input on every project. In addition, Google is known for their openness to new ideas regardless of the status or seniority of an employee. In fact, Google allows for 20% of an employee’s time can be devoted to developing new ideas and/or pet projects. HumTech.com defines a cross-functional team as a collection of people with varied levels of skills and experience brought together to accomplish a task. As the name implies, Cross-Functional Team members come from different organizational units. Cross-Functional Teams may be permanent or ad hoc. Google’s search application product strategy primarily focuses on mass customization. This is allows Google to create a base search application and allows results to be returned to the end-users quickly based on specific parameters and search settings. In addition, they also store the data that is returned in case other desire the same results based on other end-users supplying the same customized settings. This allows Google to appear to render search results in virtually real-time to the user while allowing for complete customization of the searching criteria. Greg Vogl, a professor at Uganda Martyrs University, defines mass customization as when a business gives its customers the opportunity to tailor its products or services to the customer's specifications. The IT staff at Google play a key role in ensuring that the search application’s product strategy is maintained simply because the IT staff designs, develops, and maintains all of their proprietary applications. In fact, they also maintain all network infrastructure to ensure that it is available to all end-users. References: http://www.google.com/intl/en/options/ http://ops.fhwa.dot.gov/freight/publications/ftat_user_guide/sec5.htm http://www.bridgefieldgroup.com/bridgefieldgroup/glos9.htm#V http://www.acq.osd.mil/osjtf/termsdef.html http://www.cise.ufl.edu/~mssz/Pascal-CGS2462/prog-dsn.html http://www.hfma.org/publications/business_caring_newsletter/exclusives/Supply+and+Inventory+Terms+Defined.htm http://mitsloan.mit.edu/omg/om-definition.php http://www.humtech.com/opm/grtl/ols/ols3.cfm http://www.gregvogl.net/courses/mis1/glossary.htm

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  • Developer’s Life – Attitude and Communication – They Can Cause Problems – Notes from the Field #027

    - by Pinal Dave
    [Note from Pinal]: This is a 27th episode of Notes from the Field series. The biggest challenge for anyone is to understand human nature. We human have so many things on our mind at any moment of time. There are cases when what we say is not what we mean and there are cases where what we mean we do not say. We do say and things as per our mood and our agenda in mind. Sometimes there are incidents when our attitude creates confusion in the communication and we end up creating a situation which is absolutely not warranted. In this episode of the Notes from the Field series database expert Mike Walsh explains a very crucial issue we face in our career, which is not technical but more to relate to human nature. Read on this may be the best blog post you might read in recent times. In this week’s note from the field, I’m taking a slight departure from technical knowledge and concepts explained. We’ll be back to it next week, I’m sure. Pinal wanted us to explain some of the issues we bump into and how we see some of our customers arrive at problem situations and how we have helped get them back on the right track. Often it is a technical problem we are officially solving – but in a lot of cases as a consultant, we are really helping fix some communication difficulties. This is a technical blog post and not an “advice column” in a newspaper – but the longer I am a consultant, the more years I add to my experience in technology the more I learn that the vast majority of the problems we encounter have “soft skills” included in the chain of causes for the issue we are helping overcome. This is not going to be exhaustive but I hope that sharing four pieces of advice inspired by real issues starts a process of searching for places where we can be the cause of these challenges and look at fixing them in ourselves. Or perhaps we can begin looking at resolving them in teams that we manage. I’ll share three statements that I’ve either heard, read or said and talk about some of the communication or attitude challenges highlighted by the statement. 1 – “But that’s the SAN Administrator’s responsibility…” I heard that early on in my consulting career when talking with a customer who had serious corruption and no good recent backups – potentially no good backups at all. The statement doesn’t have to be this one exactly, but the attitude here is an attitude of “my job stops here, and I don’t care about the intent or principle of why I’m here.” It’s also a situation of having the attitude that as long as there is someone else to blame, I’m fine…  You see in this case, the DBA had a suspicion that the backups were not being handled right.  They were the DBA and they knew that they had responsibility to ensure SQL backups were good to go – it’s a basic requirement of a production DBA. In my “As A DBA Where Do I start?!” presentation, I argue that is job #1 of a DBA. But in this case, the thought was that there was someone else to blame. Rather than create extra work and take on responsibility it was decided to just let it be another team’s responsibility. This failed the company, the company’s customers and no one won. As technologists – we should strive to go the extra mile. If there is a lack of clarity around roles and responsibilities and we know it – we should push to get it resolved. Especially as the DBAs who should act as the advocates of the data contained in the databases we are responsible for. 2 – “We’ve always done it this way, it’s never caused a problem before!” Complacency. I have to say that many failures I’ve been paid good money to help recover from would have not happened had it been for an attitude of complacency. If any thoughts like this have entered your mind about your situation you may be suffering from it. If, while reading this, you get this sinking feeling in your stomach about that one thing you know should be fixed but haven’t done it.. Why don’t you stop and go fix it then come back.. “We should have better backups, but we’re on a SAN so we should be fine really.” “Technically speaking that could happen, but what are the chances?” “We’ll just clean that up as a fast follow” ..and so on. In the age of tightening IT budgets, increased expectations of up time, availability and performance there is no room for complacency. Our customers and business units expect – no demand – the best. Complacency says “we will give you second best or hopefully good enough and we accept the risk and know this may hurt us later. Sometimes an organization will opt for “good enough” and I agree with the concept that at times the perfect can be the enemy of the good. But when we make those decisions in a vacuum and are not reporting them up and discussing them as an organization that is different. That is us unilaterally choosing to do something less than the best and purposefully playing a game of chance. 3 – “This device must accept interference from other devices but not create any” I’ve paraphrased this one – but it’s something the Federal Communications Commission – a federal agency in the United States that regulates electronic communication – requires of all manufacturers of any device that could cause or receive interference electronically. I blogged in depth about this here (http://www.straightpathsql.com/archives/2011/07/relationship-advice-from-the-fcc/) so I won’t go into much detail other than to say this… If we all operated more on the premise that we should do our best to not be the cause of conflict, and to be less easily offended and less upset when we perceive offense life would be easier in many areas! This doesn’t always cause the issues we are called in to help out. Not directly. But where we see it is in unhealthy relationships between the various technology teams at a client. We’ll see teams hoarding knowledge, not sharing well with others and almost working against other teams instead of working with them. If you trace these problems back far enough it often stems from someone or some group of people violating this principle from the FCC. To Sum It Up Technology problems are easy to solve. At Linchpin People we help many customers get past the toughest technological challenge – and at the end of the day it is really just a repeatable process of pattern based troubleshooting, logical thinking and starting at the beginning and carefully stepping through to the end. It’s easy at the end of the day. The tough part of what we do as consultants is the people skills. Being able to help get teams working together, being able to help teams take responsibility, to improve team to team communication? That is the difficult part, and we get to use the soft skills on every engagement. Work on professional development (http://professionaldevelopment.sqlpass.org/) and see continuing improvement here, not just with technology. I can teach just about anyone how to be an excellent DBA and performance tuner, but some of these soft skills are much more difficult to teach. If you want to get started with performance analytics and triage of virtualized SQL Servers with the help of experts, read more over at Fix Your SQL Server. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Notes from the Field, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • I want to change DPI with Imagemagick without changing the actual byte-size of the image data

    - by user1694803
    I feel so horribly sorry that I have to ask this question here, but after hours of researching how to do an actually very simple task I'm still failing... In Gimp there is a very simple way to do what I want. I only have the German dialog installed but I'll try to translate it. I'm talking about going to "Picture-PrintingSize" and then adjusting the Values "X-Resolution" and "Y-Resolution" which are known to me as so called DPI values. You can also choose the format which by default is "Pixel/Inch". (In German the dialog is "Bild-Druckgröße" and there "X-Auflösung" and "Y-Auflösung") Ok, the values there are often "72" by default. When I change them to e.g. "300" this has the effect that the image stays the same on the computer, but if I print it, it will be smaller if you look at it, but all the details are still there, just smaller - it has a higher resolution on the printed paper (but smaller size... which is fine for me). I am often doing that when I am working with LaTeX, or to be exact with the command "pdflatex" on a recent Ubuntu-Machine. When I'm doing the above process with Gimp manually everything works just fine. The images will appear smaller in the resulting PDF but with high printing quality. What I am trying to do is to automate the process of going into Gimp and adjusting the DPI values. Since Imagemagick is known to be superb and I used it for many other tasks I tried to achieve my goal with this tool. But it does just not do what I want. After trying a lot of things I think this actually is be the command that should be my friend: convert input.png -density 300 output.png This should set the DPI to 300, as I can read everywhere in the web. It seems to work. When I check the file it stays the same. file input.png output.png input.png: PNG image data, 611 x 453, 8-bit grayscale, non-interlaced output.png: PNG image data, 611 x 453, 8-bit grayscale, non-interlaced When I use this command, it seems like it did what I wanted: identify -verbose output.png | grep 300 Resolution: 300x300 PNG:pHYs : x_res=300, y_res=300, units=0 (Funny enough, the same output comes for input.png which confuses me... so this might be the wrong parameters to watch?) But when I now render my TeX with "pdflatex" the image is still big and blurry. Also when I open the image with Gimp again the DPI values are set to "72" instead of "300". So there actually was no effect at all. Now what is the problem here. Am I getting something completely wrong? I can't be that wrong since everything works just fine with Gimp... Thanks for any help in this. I am also open to other automated solutions which are easily done on a Linux system...

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  • Fun with Aggregates

    - by Paul White
    There are interesting things to be learned from even the simplest queries.  For example, imagine you are given the task of writing a query to list AdventureWorks product names where the product has at least one entry in the transaction history table, but fewer than ten. One possible query to meet that specification is: SELECT p.Name FROM Production.Product AS p JOIN Production.TransactionHistory AS th ON p.ProductID = th.ProductID GROUP BY p.ProductID, p.Name HAVING COUNT_BIG(*) < 10; That query correctly returns 23 rows (execution plan and data sample shown below): The execution plan looks a bit different from the written form of the query: the base tables are accessed in reverse order, and the aggregation is performed before the join.  The general idea is to read all rows from the history table, compute the count of rows grouped by ProductID, merge join the results to the Product table on ProductID, and finally filter to only return rows where the count is less than ten. This ‘fully-optimized’ plan has an estimated cost of around 0.33 units.  The reason for the quote marks there is that this plan is not quite as optimal as it could be – surely it would make sense to push the Filter down past the join too?  To answer that, let’s look at some other ways to formulate this query.  This being SQL, there are any number of ways to write logically-equivalent query specifications, so we’ll just look at a couple of interesting ones.  The first query is an attempt to reverse-engineer T-SQL from the optimized query plan shown above.  It joins the result of pre-aggregating the history table to the Product table before filtering: SELECT p.Name FROM ( SELECT th.ProductID, cnt = COUNT_BIG(*) FROM Production.TransactionHistory AS th GROUP BY th.ProductID ) AS q1 JOIN Production.Product AS p ON p.ProductID = q1.ProductID WHERE q1.cnt < 10; Perhaps a little surprisingly, we get a slightly different execution plan: The results are the same (23 rows) but this time the Filter is pushed below the join!  The optimizer chooses nested loops for the join, because the cardinality estimate for rows passing the Filter is a bit low (estimate 1 versus 23 actual), though you can force a merge join with a hint and the Filter still appears below the join.  In yet another variation, the < 10 predicate can be ‘manually pushed’ by specifying it in a HAVING clause in the “q1” sub-query instead of in the WHERE clause as written above. The reason this predicate can be pushed past the join in this query form, but not in the original formulation is simply an optimizer limitation – it does make efforts (primarily during the simplification phase) to encourage logically-equivalent query specifications to produce the same execution plan, but the implementation is not completely comprehensive. Moving on to a second example, the following query specification results from phrasing the requirement as “list the products where there exists fewer than ten correlated rows in the history table”: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID HAVING COUNT_BIG(*) < 10 ); Unfortunately, this query produces an incorrect result (86 rows): The problem is that it lists products with no history rows, though the reasons are interesting.  The COUNT_BIG(*) in the EXISTS clause is a scalar aggregate (meaning there is no GROUP BY clause) and scalar aggregates always produce a value, even when the input is an empty set.  In the case of the COUNT aggregate, the result of aggregating the empty set is zero (the other standard aggregates produce a NULL).  To make the point really clear, let’s look at product 709, which happens to be one for which no history rows exist: -- Scalar aggregate SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = 709;   -- Vector aggregate SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = 709 GROUP BY th.ProductID; The estimated execution plans for these two statements are almost identical: You might expect the Stream Aggregate to have a Group By for the second statement, but this is not the case.  The query includes an equality comparison to a constant value (709), so all qualified rows are guaranteed to have the same value for ProductID and the Group By is optimized away. In fact there are some minor differences between the two plans (the first is auto-parameterized and qualifies for trivial plan, whereas the second is not auto-parameterized and requires cost-based optimization), but there is nothing to indicate that one is a scalar aggregate and the other is a vector aggregate.  This is something I would like to see exposed in show plan so I suggested it on Connect.  Anyway, the results of running the two queries show the difference at runtime: The scalar aggregate (no GROUP BY) returns a result of zero, whereas the vector aggregate (with a GROUP BY clause) returns nothing at all.  Returning to our EXISTS query, we could ‘fix’ it by changing the HAVING clause to reject rows where the scalar aggregate returns zero: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID HAVING COUNT_BIG(*) BETWEEN 1 AND 9 ); The query now returns the correct 23 rows: Unfortunately, the execution plan is less efficient now – it has an estimated cost of 0.78 compared to 0.33 for the earlier plans.  Let’s try adding a redundant GROUP BY instead of changing the HAVING clause: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY th.ProductID HAVING COUNT_BIG(*) < 10 ); Not only do we now get correct results (23 rows), this is the execution plan: I like to compare that plan to quantum physics: if you don’t find it shocking, you haven’t understood it properly :)  The simple addition of a redundant GROUP BY has resulted in the EXISTS form of the query being transformed into exactly the same optimal plan we found earlier.  What’s more, in SQL Server 2008 and later, we can replace the odd-looking GROUP BY with an explicit GROUP BY on the empty set: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () HAVING COUNT_BIG(*) < 10 ); I offer that as an alternative because some people find it more intuitive (and it perhaps has more geek value too).  Whichever way you prefer, it’s rather satisfying to note that the result of the sub-query does not exist for a particular correlated value where a vector aggregate is used (the scalar COUNT aggregate always returns a value, even if zero, so it always ‘EXISTS’ regardless which ProductID is logically being evaluated). The following query forms also produce the optimal plan and correct results, so long as a vector aggregate is used (you can probably find more equivalent query forms): WHERE Clause SELECT p.Name FROM Production.Product AS p WHERE ( SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () ) < 10; APPLY SELECT p.Name FROM Production.Product AS p CROSS APPLY ( SELECT NULL FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () HAVING COUNT_BIG(*) < 10 ) AS ca (dummy); FROM Clause SELECT q1.Name FROM ( SELECT p.Name, cnt = ( SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () ) FROM Production.Product AS p ) AS q1 WHERE q1.cnt < 10; This last example uses SUM(1) instead of COUNT and does not require a vector aggregate…you should be able to work out why :) SELECT q.Name FROM ( SELECT p.Name, cnt = ( SELECT SUM(1) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID ) FROM Production.Product AS p ) AS q WHERE q.cnt < 10; The semantics of SQL aggregates are rather odd in places.  It definitely pays to get to know the rules, and to be careful to check whether your queries are using scalar or vector aggregates.  As we have seen, query plans do not show in which ‘mode’ an aggregate is running and getting it wrong can cause poor performance, wrong results, or both. © 2012 Paul White Twitter: @SQL_Kiwi email: [email protected]

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  • Where's the Swap File/Partition?

    - by chrisbunney
    I'm investigating the virtual memory configuration of a Debian based Amazon EC2 instance, and as my background isn't in system admin, I'm slightly confused by what I'm seeing. We're using MongoDB, and the monitoring server we have indicates that the Mongo process is using about 20GB of swap space, however I can't figure out where this is located on the server. As far as I can tell from using the various suggested methods from Google, there is either a much smaller amount, or none at all. top indicates that there is 1.8GB of swap memory: top - 15:35:21 up 6 days, 3:23, 1 user, load average: 1.60, 1.43, 1.37 Tasks: 47 total, 2 running, 45 sleeping, 0 stopped, 0 zombie Cpu(s): 0.0%us, 1.3%sy, 0.0%ni, 14.7%id, 83.8%wa, 0.0%hi, 0.0%si, 0.1%st Mem: 3928924k total, 2855572k used, 1073352k free, 640564k buffers Swap: 0k total, 0k used, 0k free, 1887788k cached swapon -s doesn't seem to think there's any swap space: Filename Type Size Used Priority free -m doesn't think there's any swap either: total used free shared buffers cached Mem: 3836 3663 172 0 626 2701 -/+ buffers/cache: 336 3500 Swap: 0 0 0 And neither does vmstat: procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 3 0 66224 641372 2874744 0 0 21 5012 21 33 2 2 76 19 But cat /etc/fstab thinks there is a swap partition: /dev/xvda1 / ext3 defaults 1 1 /dev/xvda2 /mnt ext3 defaults 0 0 /dev/xvda3 swap swap defaults 0 0 none /proc proc defaults 0 0 none /sys sysfs defaults 0 0 However df -k gives no indication of the xvda3 partition: Filesystem 1K-blocks Used Available Use% Mounted on /dev/xvda1 16513960 15675324 0 100% / tmpfs 1964460 8 1964452 1% /lib/init/rw udev 1914148 28 1914120 1% /dev tmpfs 1964460 4 1964456 1% /dev/shm So I really don't know what to make of this, because I appear to have a process using about 10 times more virtual memory than what might be available, and I have no idea where this virtual memory is on the system. I'm probably misinterpreting the output of the tools, so I'd be grateful if someone would be able to set me straight: What have I got wrong, what's the right interpretation, and how do you reach that interpretation? EDIT0: We use 10gen's MMS for monitoring the database, the relevant section for memory from the last data point is: "mem": { "virtual": 20749, "bits": 64, "supported": true, "mappedWithJournal": 20376, "mapped": 10188, "resident": 1219 }, This JSON is specific to the database process (I believe) rather than the system as a whole. fdisk -l /dev/xvda outputs... nothing? I tried each of the 3 xvda entries in /etc/fstab as well: root@ip:~# fdisk -l /dev/xvda1 Disk /dev/xvda1: 34.4 GB, 34359738368 bytes 255 heads, 63 sectors/track, 4177 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/xvda1 doesn't contain a valid partition table root@ip:~# fdisk -l /dev/xvda2 root@ip:~# fdisk -l /dev/xvda3 root@ip:~# Edit1: Output of cat /proc/meminfo for the sake of completeness: MemTotal: 3928924 kB MemFree: 726600 kB Buffers: 648368 kB Cached: 2216556 kB SwapCached: 0 kB Active: 1945100 kB Inactive: 994016 kB Active(anon): 60476 kB Inactive(anon): 12952 kB Active(file): 1884624 kB Inactive(file): 981064 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 0 kB SwapFree: 0 kB Dirty: 387180 kB Writeback: 0 kB AnonPages: 73380 kB Mapped: 1188260 kB Shmem: 48 kB Slab: 149768 kB SReclaimable: 146076 kB SUnreclaim: 3692 kB KernelStack: 1104 kB PageTables: 16096 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 1964460 kB Committed_AS: 305572 kB VmallocTotal: 34359738367 kB VmallocUsed: 16760 kB VmallocChunk: 34359721448 kB HardwareCorrupted: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 3932160 kB DirectMap2M: 0 kB

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  • CodePlex Daily Summary for Tuesday, March 23, 2010

    CodePlex Daily Summary for Tuesday, March 23, 2010New Projects.NET StarCraft II Replay Parser: A .NET 3.5 Library used to parse StarCraft II replays. Developed in C# 3.5.BackToBasics "B2B" Chat: With technology and software getting more and more complicated, why not get back to basics with BackToBasicsChat. B2B allows you to chat over a ser...Dark Neuron Game Engine: Dark Neuron allows you to easily create fun and interesting games with no need of developing basic game components. This engine is developed for C#...DeepZoom Pivot Constructor: Library to make building DeepZoom images and Pivot displays simpler.ePaper reader: The project is aimed at creating a tool which helps in reading electronic editions of news papers(pdf/flash)FSharpPageProvider for EPiServer CMS 6: This project starts as the port of EPiServer XmlPageProvider to F# programming language. Hammock for REST: Hammock is a REST library for .NET that greatly simplifies consuming and wrapping RESTful services.Kirill Osenkov: Various small projects, tools, utilities and samples by Kirill OsenkovliveDB: liveDB - web client for sql serverLucilla Framework: lucilla frameworkMVC Foolproof Validation: MVC Foolproof Validation aims to extend the Data Annotation validation provided in ASP.NET MVC. Initial efforts are focused on adding contingent va...MVC2Forums: MVC2Forums is simply a forum system based upon MVC2.Mvvm Foundation Silverlight: Mvvm Foundation Silverlight is a library of classes that are helpful when building Silverlight applications based in the MVVM pattern. This librar...MyPersonalWebsite: This is my personal web site developed using ASP.NET MVC 2Planner: Planner makes it easier for all peoples to plan your tasks. It's developed in Delphi.Prose: Prose is an playground for an experimental JavaScript like language compiler. Eventually it will implement 0-CFA, CFA2, and a Tracing JITQuestTracker: QuestTracker is a todo list presented in the format of a quest tracking list such as the one in World of Warcraft.SevenZipLib: SevenZipLib is a C# interface to the 7-zip library.SimpleGeo .Net: .Net Client library for the SimpleGeo.com serviceNew ReleasesAutenticar no OpenLDAP utilizando pGIna: DLL LDAPAuth Plus: New Group: No LoginBMap.NET: BMap.NET 2: This is the 2nd version of BMap.NET. It has included these tags: Bing Maps, and "About BMap.NET".Cronos: Version 2.04: This is primarily a bug-fix release. Several numerical issues have been resolved, and a resource leak (of MS Windows graphics objects) has been fi...EV Dashboard: v1.0: This release includes support for an App.config file and Auto Connect, which will connect to the specified BMS at startup. Note: You still have to ...GKO Libraries: GKO Libraries 0.1 Beta: 0.1 Beta Added More utilities and functions RefactoringsGLB Virtual Player Builder: 0.4.2 Beta: Beta build that includes a new player creator.HKGolden Express: HKGoldenExpress (Build 201003222215): New features: (None) Bug fix: Fixed bugs of unable to parse XML file stream returned from HKGolden API, as the encoding of XML file stream chang...jQuery Web Controls ASP.Net: jQueryWebControls 1.1.1.2: En esta versión se han corregido problemas existentes en la ejecución de los scripts de jquery cuando se utilizaban MasterPage y/o Ajax Control Too...LightKit: Version 0.2.2: Fixed: fixed bug when CollectionItemsEditor ditermines IsChanged property incorrectly fixed ObjectEditor`a thisstring propertyName method wrong l...LINQ to Twitter: LINQ to Twitter Beta v2.0.8: New items added since v1.1 include: Support for OAuth (via DotNetOpenAuth), secure communication via https, VB language support, serialization of ...MapWindow6: MapWindow 6.0 msi (March 22): This version fixes the icons for the desktop installer and changes the install directory to Program Files\MapWindow instead of Program Files\ISU.Math.NET Numerics: 2010.3.22.1334 Build: Latest alpha buildMiniCalendar Web Part: MiniCalendar Web Part 1.8: A small web part to display links to events stored in a list (or document library) in a mini calendar (in month view mode). It shows tooltips for t...OCInject: Release Two: This release brings some missing features such as Singleton support, Func<T> factories and child containers. It, also, has an updated constructor ...Phalanger - The PHP Language Compiler for the .NET Framework: 2.0 (March 2010): Installer of the latest binaries of Phalanger 2.0 (March 2010) and its integration into Visual Studio 2008. Easy installer with automatic IIS int...Planner: Planner: firstQuestTracker: QuestTracker 0.1: This is the preliminary release of QuestTracker. There's not much documentation or many features yet, but it is functional. Any feedback would be a...QuestTracker: QuestTracker 0.1.1: Bugfix for QuestTracker 0.1QuestTracker: QuestTracker 0.1.2: Fixes an issue with saving the quest list.Rawr: Rawr 2.3.13: We're pleased to announce that, after long last, Rawr3 has entered public beta. You're still welcome to continue using Rawr2 (that's what you're re...Single Web Session: Alpha Model Plugin: !How to use Single Web Session add following line into your web config <httpModules> <add name="SingleSession" type="SingleWebSession.Model.W...SMIL - SharePoint Map Integration Layer: SMIL 1.0: Custom data field Extracts Lat/Lon from EXIF from images being uploaded. Map Web Part Filter with SharePoint views Filter by connecting to...sTASKedit: sTASKedit 42532 (Developer Alpha): This release is only to verify the currently decoded task structure... Supported files: tasks.data (v1.3.6 client)VCC: Latest build, v2.1.30322.0: Automatic drop of latest buildVisual Studio DSite: Advanced Notepad (Visual C++ 2008): An notepad written in c that can save in a rich text file format.Wallpaper Rotator: Wallpaper Rotator 0.5: Wallpaper Rotator 0.5 This version includes the following improvements: Saving the choice of "Random Order (Shuffle Mode)" Updating the configu...Most Popular ProjectsMetaSharpRawrWBFS ManagerSilverlight ToolkitASP.NET Ajax LibraryMicrosoft SQL Server Product Samples: DatabaseAJAX Control ToolkitLiveUpload to FacebookWindows Presentation Foundation (WPF)ASP.NETMost Active ProjectsRawrjQuery Library for SharePoint Web ServicesBlogEngine.NETLINQ to TwitterPHPExcelFarseer Physics EngineFacebook Developer ToolkitNB_Store - Free DotNetNuke Ecommerce Catalog Modulepatterns & practices: Composite WPF and SilverlightN2 CMS

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  • External usb 3.0 hard drive is not recognised when plugged into usb 3 port (ubuntu natty 64 bit).

    - by kimangroo
    I have an Iomega Prestige Portable External Hard Drive 1TB USB 3.0. It works fine on windows 7 as a usb 3.0 drive. It isn't detected on ubuntu natty 64bit, 2.6.38-8-generic. fdisk -l cannot see it at all: Disk /dev/sda: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x1bed746b Device Boot Start End Blocks Id System /dev/sda1 1 1689 13560832 27 Unknown /dev/sda2 * 1689 1702 102400 7 HPFS/NTFS /dev/sda3 1702 19978 146805760 7 HPFS/NTFS /dev/sda4 19978 60802 327914497 5 Extended /dev/sda5 25555 60802 283120640 7 HPFS/NTFS /dev/sda6 19978 23909 31571968 83 Linux /dev/sda7 23909 25555 13218816 82 Linux swap / Solaris Partition table entries are not in disk order lsusb can see it: Bus 003 Device 003: ID 059b:0070 Iomega Corp. Bus 003 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 002 Device 004: ID 05fe:0011 Chic Technology Corp. Browser Mouse Bus 002 Device 003: ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode) Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 005: ID 0489:e00f Foxconn / Hon Hai Bus 001 Device 004: ID 0c45:64b5 Microdia Bus 001 Device 003: ID 08ff:168f AuthenTec, Inc. Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub And dmesg | grep -i xhci (I may have unplugged the drive and plugged it back in again after booting): [ 1.659060] pci 0000:04:00.0: xHCI HW did not halt within 2000 usec status = 0x0 [ 11.484971] xhci_hcd 0000:04:00.0: PCI INT A -> GSI 18 (level, low) -> IRQ 18 [ 11.484997] xhci_hcd 0000:04:00.0: setting latency timer to 64 [ 11.485002] xhci_hcd 0000:04:00.0: xHCI Host Controller [ 11.485064] xhci_hcd 0000:04:00.0: new USB bus registered, assigned bus number 3 [ 11.636149] xhci_hcd 0000:04:00.0: irq 18, io mem 0xc5400000 [ 11.636241] xhci_hcd 0000:04:00.0: irq 43 for MSI/MSI-X [ 11.636246] xhci_hcd 0000:04:00.0: irq 44 for MSI/MSI-X [ 11.636251] xhci_hcd 0000:04:00.0: irq 45 for MSI/MSI-X [ 11.636256] xhci_hcd 0000:04:00.0: irq 46 for MSI/MSI-X [ 11.636261] xhci_hcd 0000:04:00.0: irq 47 for MSI/MSI-X [ 11.639654] xHCI xhci_add_endpoint called for root hub [ 11.639655] xHCI xhci_check_bandwidth called for root hub [ 11.956366] usb 3-1: new SuperSpeed USB device using xhci_hcd and address 2 [ 12.001073] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 12.007059] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 12.012932] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 12.018922] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 12.049139] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 12.056754] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 12.131607] xhci_hcd 0000:04:00.0: WARN no SS endpoint bMaxBurst [ 12.179717] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 12.686876] xhci_hcd 0000:04:00.0: WARN: babble error on endpoint [ 12.687058] xhci_hcd 0000:04:00.0: WARN Set TR Deq Ptr cmd invalid because of stream ID configuration [ 12.687152] xhci_hcd 0000:04:00.0: ERROR Transfer event for disabled endpoint or incorrect stream ring [ 43.330737] usb 3-1: reset SuperSpeed USB device using xhci_hcd and address 2 [ 43.422579] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 43.422658] xhci_hcd 0000:04:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff88014669af00 [ 43.422665] xhci_hcd 0000:04:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff88014669af40 [ 43.422671] xhci_hcd 0000:04:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff88014669af80 [ 43.422677] xhci_hcd 0000:04:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff88014669afc0 [ 43.531159] xhci_hcd 0000:04:00.0: WARN no SS endpoint bMaxBurst [ 125.160248] xhci_hcd 0000:04:00.0: WARN no SS endpoint bMaxBurst [ 903.766466] usb 3-1: new SuperSpeed USB device using xhci_hcd and address 3 [ 903.807789] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 903.813530] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 903.819400] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 903.825104] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 903.855067] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 903.862314] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 903.862597] xhci_hcd 0000:04:00.0: WARN no SS endpoint bMaxBurst [ 903.913211] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 904.424416] xhci_hcd 0000:04:00.0: WARN: babble error on endpoint [ 904.424599] xhci_hcd 0000:04:00.0: WARN Set TR Deq Ptr cmd invalid because of stream ID configuration [ 904.424700] xhci_hcd 0000:04:00.0: ERROR Transfer event for disabled endpoint or incorrect stream ring [ 935.139021] usb 3-1: reset SuperSpeed USB device using xhci_hcd and address 3 [ 935.226075] xhci_hcd 0000:04:00.0: WARN: short transfer on control ep [ 935.226140] xhci_hcd 0000:04:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff880148186b00 [ 935.226148] xhci_hcd 0000:04:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff880148186b40 [ 935.226153] xhci_hcd 0000:04:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff880148186b80 [ 935.226159] xhci_hcd 0000:04:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff880148186bc0 [ 935.343339] xhci_hcd 0000:04:00.0: WARN no SS endpoint bMaxBurst I thought it might be that the firmware wasn't compatible with linux or something, but when booting a live image of partedmagic, (2.6.38.4-pmagic), the drive was detected fine, I could mount it and got usb 3.0 speeds (at least they double the speeds I got from plugging same drive in usb 2 ports). dmesg in partedmagic did say something about no SuperSpeed endpoint which was an error I saw in a previous dmesg of ubuntu: Jun 27 15:49:02 (none) user.info kernel: [ 2.978743] xhci_hcd 0000:04:00.0: PCI INT A -> GSI 18 (level, low) -> IRQ 18 Jun 27 15:49:02 (none) user.debug kernel: [ 2.978771] xhci_hcd 0000:04:00.0: setting latency timer to 64 Jun 27 15:49:02 (none) user.info kernel: [ 2.978781] xhci_hcd 0000:04:00.0: xHCI Host Controller Jun 27 15:49:02 (none) user.info kernel: [ 2.978856] xhci_hcd 0000:04:00.0: new USB bus registered, assigned bus number 3 Jun 27 15:49:02 (none) user.info kernel: [ 3.089458] xhci_hcd 0000:04:00.0: irq 18, io mem 0xc5400000 Jun 27 15:49:02 (none) user.debug kernel: [ 3.089541] xhci_hcd 0000:04:00.0: irq 42 for MSI/MSI-X Jun 27 15:49:02 (none) user.debug kernel: [ 3.089544] xhci_hcd 0000:04:00.0: irq 43 for MSI/MSI-X Jun 27 15:49:02 (none) user.debug kernel: [ 3.089546] xhci_hcd 0000:04:00.0: irq 44 for MSI/MSI-X Jun 27 15:49:02 (none) user.debug kernel: [ 3.089548] xhci_hcd 0000:04:00.0: irq 45 for MSI/MSI-X Jun 27 15:49:02 (none) user.debug kernel: [ 3.089550] xhci_hcd 0000:04:00.0: irq 46 for MSI/MSI-X Jun 27 15:49:02 (none) user.warn kernel: [ 3.092857] usb usb3: No SuperSpeed endpoint companion for config 1 interface 0 altsetting 0 ep 129: using minimum values Jun 27 15:49:02 (none) user.info kernel: [ 3.092864] usb usb3: New USB device found, idVendor=1d6b, idProduct=0003 Jun 27 15:49:02 (none) user.info kernel: [ 3.092866] usb usb3: New USB device strings: Mfr=3, Product=2, SerialNumber=1 Jun 27 15:49:02 (none) user.info kernel: [ 3.092867] usb usb3: Product: xHCI Host Controller Jun 27 15:49:02 (none) user.info kernel: [ 3.092869] usb usb3: Manufacturer: Linux 2.6.38.4-pmagic xhci_hcd Jun 27 15:49:02 (none) user.info kernel: [ 3.092870] usb usb3: SerialNumber: 0000:04:00.0 Jun 27 15:49:02 (none) user.debug kernel: [ 3.092961] xHCI xhci_add_endpoint called for root hub Jun 27 15:49:02 (none) user.debug kernel: [ 3.092963] xHCI xhci_check_bandwidth called for root hub Well I have no idea what's going wrong, and I haven't had much luck from google and the forums so far. A number of unanswered threads with people with similar error messages and problems only. Hopefully someone here can help or point me in the right direction?!

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  • Can Microsoft Build Appliances?

    - by andrewbrust
    Billy Hollis, my Visual Studio Live! colleague and fellow Microsoft Regional Director said recently, and I am paraphrasing, that the computing world, especially on the consumer side, has shifted from one of building hardware and software that makes things possible to do, to building products and technologies that make things easy to do.  Billy crystalized things perfectly, as he often does. In this new world of “easy to do,” Apple has done very well and Microsoft has struggled.  In the old world, customers wanted a Swiss Army Knife, with the most gimmicks and gadgets possible.  In the new world, people want elegantly cutlery.  They may want cake cutters and utility knives too, but they don’t want one device that works for all three tasks.  People don’t want tools, they want utensils.  People don’t want machines.  They want appliances. Microsoft Appliances: They Do Exist Microsoft has built a few appliance-like devices.  I would say XBox 360 is an appliance,  It’s versatile, mind you, but it’s the kind of thing you plug in, turn on and use, as opposed to set-up, tune, and open up to upgrade the internals.  Windows Phone 7 is an appliance too.  It’s a true smartphone, unlike Windows Mobile which was a handheld computer with a radio stack.  Zune is an appliance too, and a nice one.  It hasn’t attained much traction in the market, but that’s probably because the seminal consumer computing appliance -- the iPod – got there so much more quickly. In the embedded world, Mediaroom, Microsoft’s set-top product for the cable industry (used by AT&T U-Verse and others) is an appliance.  So is Microsoft’s Sync technology, used in Ford automobiles.  Even on the enterprise side, Microsoft has an appliance: SQL Server Parallel Data Warehouse Edition (PDW) combines Microsoft software with select OEMs’ server, networking and storage hardware.  You buy the appliance units from the OEMs, plug them in, connect them and go. I would even say that Bing is an appliance.  Not in the hardware sense, mind you.  But from the software perspective, it’s a single-purpose product that you visit or run, use and then move on.  You don’t have to install it (except the iOS and Android native apps where it’s pretty straightforward), you don’t have to customize it, you don’t have to program it.  Basically, you just use it. Microsoft Appliances that Should Exist But Microsoft builds a bunch of things that are not appliances.  Media Center is not an appliance, and it most certainly should be.  Instead, it’s an app that runs on Windows 7.  It runs full-screen and you can use this configuration to conceal the fact that Windows is under it, but eventually something will cause you to abandon that masquerade (like Patch Tuesday). The next version of Windows Home Server won’t, in my opinion, be an appliance either.  Now that the Drive Extender technology is gone, and users can’t just add and remove drives into and from a single storage pool, the product is much more like a IT server and less like an appliance-premised one.  Much has been written about this decision by Microsoft.  I’ll just sum it up in one word: pity. Microsoft doesn’t have anything remotely appliance-like in the tablet category, either.  Until it does, it likely won’t have much market share in that space either.  And of course, the bulk of Microsoft’s product catalog on the business side is geared to enterprise machines and not personal appliances. Appliance DNA: They Gotta Have It. The consumerization of IT is real, because businesspeople are consumers too.  They appreciate the fit and finish of appliances at home, and they increasingly feel entitled to have it at work too.  Secure and reliable push email in a smartphone is necessary, but it isn’t enough.  People want great apps and a pleasurable user experience too.  The full Microsoft Office product is needed at work, but a PC with a keyboard and mouse, or maybe a touch screen that uses a stylus (or requires really small fingers), to run Office isn’t enough either.  People want a flawless touch experience available for the times they want to read and take quick notes.  Until Microsoft realizes this fully and internalizes it, it will suffer defeats in the consumer market and even setbacks in the business market.  Think about how slow the Office upgrade cycle is…now imagine if the next version of Office had a first-class alternate touch UI and consider the possible acceleration in adoption rates. Can Microsoft make the appliance switch?  Can the appliance mentality become pervasive at the company?  Can Microsoft hasten its release cycles dramatically and shed the “some assembly required” paradigm upon which many of its products are based?  Let’s face it, the chances that Microsoft won’t make this transition are significant. But there are also encouraging signs, and they should not be ignored.  The appliances we have already discussed, especially Xbox, Zune and Windows Phone 7, are the most obvious in this regard.  The fact that SQL Server has an appliance SKU now is a more subtle but perhaps also more significant outcome, because that product sits so smack in the middle of Microsoft’s enterprise stack.  Bing is encouraging too, especially given its integrated travel, maps and augmented reality capabilities.  As Bing gains market share, Microsoft has tangible proof that it can transform and win, even when everyone outside the company, and many within it, would bet otherwise. That Great Big Appliance in the Sky Perhaps the most promising (and evolving) proof points toward the appliance mentality, though, are Microsoft’s cloud offerings -- Azure and BPOS/Office 365.  While the cloud does not represent a physical appliance (quite the opposite in fact) its ability to make acquisition, deployment and use of technology simple for the user is absolutely an embodiment of the appliance mentality and spirit.  Azure is primarily a platform as a service offering; it doesn’t just provide infrastructure.  SQL Azure does likewise for databases.  And Office 365 does likewise for SharePoint, Exchange and Lync. You don’t administer, tune and manage servers; instead, you create databases or site collections or mailboxes and start using them. Upgrades come automatically, and it seems like releases will come more frequently.  Fault tolerance and content distribution is just there.  No muss.  No fuss.  You use these services; you don’t have to set them up and think about them.  That’s how appliances work.  To me, these signs point out that Microsoft has the full capability of transforming itself.  But there’s a lot of work ahead.  Microsoft may say they’re “all in” on the cloud, but the majority of the company is still oriented around its old products and models.  There needs to be a wholesale cultural transformation in Redmond.  It can happen, but product management, program management, the field and executive ranks must unify in the effort. So must partners, and even customers.  New leaders must rise up and Microsoft must be able to see itself as a winner.  If Microsoft does this, it could lock-in decades of new success, and be a standard business school case study for doing so.  If not, the company will have missed an opportunity, and may see its undoing.

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  • How accurate is "Business logic should be in a service, not in a model"?

    - by Jeroen Vannevel
    Situation Earlier this evening I gave an answer to a question on StackOverflow. The question: Editing of an existing object should be done in repository layer or in service? For example if I have a User that has debt. I want to change his debt. Should I do it in UserRepository or in service for example BuyingService by getting an object, editing it and saving it ? My answer: You should leave the responsibility of mutating an object to that same object and use the repository to retrieve this object. Example situation: class User { private int debt; // debt in cents private string name; // getters public void makePayment(int cents){ debt -= cents; } } class UserRepository { public User GetUserByName(string name){ // Get appropriate user from database } } A comment I received: Business logic should really be in a service. Not in a model. What does the internet say? So, this got me searching since I've never really (consciously) used a service layer. I started reading up on the Service Layer pattern and the Unit Of Work pattern but so far I can't say I'm convinced a service layer has to be used. Take for example this article by Martin Fowler on the anti-pattern of an Anemic Domain Model: There are objects, many named after the nouns in the domain space, and these objects are connected with the rich relationships and structure that true domain models have. The catch comes when you look at the behavior, and you realize that there is hardly any behavior on these objects, making them little more than bags of getters and setters. Indeed often these models come with design rules that say that you are not to put any domain logic in the the domain objects. Instead there are a set of service objects which capture all the domain logic. These services live on top of the domain model and use the domain model for data. (...) The logic that should be in a domain object is domain logic - validations, calculations, business rules - whatever you like to call it. To me, this seemed exactly what the situation was about: I advocated the manipulation of an object's data by introducing methods inside that class that do just that. However I realize that this should be a given either way, and it probably has more to do with how these methods are invoked (using a repository). I also had the feeling that in that article (see below), a Service Layer is more considered as a façade that delegates work to the underlying model, than an actual work-intensive layer. Application Layer [his name for Service Layer]: Defines the jobs the software is supposed to do and directs the expressive domain objects to work out problems. The tasks this layer is responsible for are meaningful to the business or necessary for interaction with the application layers of other systems. This layer is kept thin. It does not contain business rules or knowledge, but only coordinates tasks and delegates work to collaborations of domain objects in the next layer down. It does not have state reflecting the business situation, but it can have state that reflects the progress of a task for the user or the program. Which is reinforced here: Service interfaces. Services expose a service interface to which all inbound messages are sent. You can think of a service interface as a façade that exposes the business logic implemented in the application (typically, logic in the business layer) to potential consumers. And here: The service layer should be devoid of any application or business logic and should focus primarily on a few concerns. It should wrap Business Layer calls, translate your Domain in a common language that your clients can understand, and handle the communication medium between server and requesting client. This is a serious contrast to other resources that talk about the Service Layer: The service layer should consist of classes with methods that are units of work with actions that belong in the same transaction. Or the second answer to a question I've already linked: At some point, your application will want some business logic. Also, you might want to validate the input to make sure that there isn't something evil or nonperforming being requested. This logic belongs in your service layer. "Solution"? Following the guidelines in this answer, I came up with the following approach that uses a Service Layer: class UserController : Controller { private UserService _userService; public UserController(UserService userService){ _userService = userService; } public ActionResult MakeHimPay(string username, int amount) { _userService.MakeHimPay(username, amount); return RedirectToAction("ShowUserOverview"); } public ActionResult ShowUserOverview() { return View(); } } class UserService { private IUserRepository _userRepository; public UserService(IUserRepository userRepository) { _userRepository = userRepository; } public void MakeHimPay(username, amount) { _userRepository.GetUserByName(username).makePayment(amount); } } class UserRepository { public User GetUserByName(string name){ // Get appropriate user from database } } class User { private int debt; // debt in cents private string name; // getters public void makePayment(int cents){ debt -= cents; } } Conclusion All together not much has changed here: code from the controller has moved to the service layer (which is a good thing, so there is an upside to this approach). However this doesn't look like it had anything to do with my original answer. I realize design patterns are guidelines, not rules set in stone to be implemented whenever possible. Yet I have not found a definitive explanation of the service layer and how it should be regarded. Is it a means to simply extract logic from the controller and put it inside a service instead? Is it supposed to form a contract between the controller and the domain? Should there be a layer between the domain and the service layer? And, last but not least: following the original comment Business logic should really be in a service. Not in a model. Is this correct? How would I introduce my business logic in a service instead of the model?

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  • WebSocket Applications using Java: JSR 356 Early Draft Now Available (TOTD #183)

    - by arungupta
    WebSocket provide a full-duplex and bi-directional communication protocol over a single TCP connection. JSR 356 is defining a standard API for creating WebSocket applications in the Java EE 7 Platform. This Tip Of The Day (TOTD) will provide an introduction to WebSocket and how the JSR is evolving to support the programming model. First, a little primer on WebSocket! WebSocket is a combination of IETF RFC 6455 Protocol and W3C JavaScript API (still a Candidate Recommendation). The protocol defines an opening handshake and data transfer. The API enables Web pages to use the WebSocket protocol for two-way communication with the remote host. Unlike HTTP, there is no need to create a new TCP connection and send a chock-full of headers for every message exchange between client and server. The WebSocket protocol defines basic message framing, layered over TCP. Once the initial handshake happens using HTTP Upgrade, the client and server can send messages to each other, independent from the other. There are no pre-defined message exchange patterns of request/response or one-way between client and and server. These need to be explicitly defined over the basic protocol. The communication between client and server is pretty symmetric but there are two differences: A client initiates a connection to a server that is listening for a WebSocket request. A client connects to one server using a URI. A server may listen to requests from multiple clients on the same URI. Other than these two difference, the client and server behave symmetrically after the opening handshake. In that sense, they are considered as "peers". After a successful handshake, clients and servers transfer data back and forth in conceptual units referred as "messages". On the wire, a message is composed of one or more frames. Application frames carry payload intended for the application and can be text or binary data. Control frames carry data intended for protocol-level signaling. Now lets talk about the JSR! The Java API for WebSocket is worked upon as JSR 356 in the Java Community Process. This will define a standard API for building WebSocket applications. This JSR will provide support for: Creating WebSocket Java components to handle bi-directional WebSocket conversations Initiating and intercepting WebSocket events Creation and consumption of WebSocket text and binary messages The ability to define WebSocket protocols and content models for an application Configuration and management of WebSocket sessions, like timeouts, retries, cookies, connection pooling Specification of how WebSocket application will work within the Java EE security model Tyrus is the Reference Implementation for JSR 356 and is already integrated in GlassFish 4.0 Promoted Builds. And finally some code! The API allows to create WebSocket endpoints using annotations and interface. This TOTD will show a simple sample using annotations. A subsequent blog will show more advanced samples. A POJO can be converted to a WebSocket endpoint by specifying @WebSocketEndpoint and @WebSocketMessage. @WebSocketEndpoint(path="/hello")public class HelloBean {     @WebSocketMessage    public String sayHello(String name) {         return "Hello " + name + "!";     }} @WebSocketEndpoint marks this class as a WebSocket endpoint listening at URI defined by the path attribute. The @WebSocketMessage identifies the method that will receive the incoming WebSocket message. This first method parameter is injected with payload of the incoming message. In this case it is assumed that the payload is text-based. It can also be of the type byte[] in case the payload is binary. A custom object may be specified if decoders attribute is specified in the @WebSocketEndpoint. This attribute will provide a list of classes that define how a custom object can be decoded. This method can also take an optional Session parameter. This is injected by the runtime and capture a conversation between two endpoints. The return type of the method can be String, byte[] or a custom object. The encoders attribute on @WebSocketEndpoint need to define how a custom object can be encoded. The client side is an index.jsp with embedded JavaScript. The JSP body looks like: <div style="text-align: center;"> <form action="">     <input onclick="say_hello()" value="Say Hello" type="button">         <input id="nameField" name="name" value="WebSocket" type="text"><br>    </form> </div> <div id="output"></div> The code is relatively straight forward. It has an HTML form with a button that invokes say_hello() method and a text field named nameField. A div placeholder is available for displaying the output. Now, lets take a look at some JavaScript code: <script language="javascript" type="text/javascript"> var wsUri = "ws://localhost:8080/HelloWebSocket/hello";     var websocket = new WebSocket(wsUri);     websocket.onopen = function(evt) { onOpen(evt) };     websocket.onmessage = function(evt) { onMessage(evt) };     websocket.onerror = function(evt) { onError(evt) };     function init() {         output = document.getElementById("output");     }     function say_hello() {      websocket.send(nameField.value);         writeToScreen("SENT: " + nameField.value);     } This application is deployed as "HelloWebSocket.war" (download here) on GlassFish 4.0 promoted build 57. So the WebSocket endpoint is listening at "ws://localhost:8080/HelloWebSocket/hello". A new WebSocket connection is initiated by specifying the URI to connect to. The JavaScript API defines callback methods that are invoked when the connection is opened (onOpen), closed (onClose), error received (onError), or a message from the endpoint is received (onMessage). The client API has several send methods that transmit data over the connection. This particular script sends text data in the say_hello method using nameField's value from the HTML shown earlier. Each click on the button sends the textbox content to the endpoint over a WebSocket connection and receives a response based upon implementation in the sayHello method shown above. How to test this out ? Download the entire source project here or just the WAR file. Download GlassFish4.0 build 57 or later and unzip. Start GlassFish as "asadmin start-domain". Deploy the WAR file as "asadmin deploy HelloWebSocket.war". Access the application at http://localhost:8080/HelloWebSocket/index.jsp. After clicking on "Say Hello" button, the output would look like: Here are some references for you: WebSocket - Protocol and JavaScript API JSR 356: Java API for WebSocket - Specification (Early Draft) and Implementation (already integrated in GlassFish 4 promoted builds) Subsequent blogs will discuss the following topics (not necessary in that order) ... Binary data as payload Custom payloads using encoder/decoder Error handling Interface-driven WebSocket endpoint Java client API Client and Server configuration Security Subprotocols Extensions Other topics from the API Capturing WebSocket on-the-wire messages

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  • Cost Comparison Hard Disk Drive to Solid State Drive on Price per Gigabyte - dispelling a myth!

    - by tonyrogerson
    It is often said that Hard Disk Drive storage is significantly cheaper per GiByte than Solid State Devices – this is wholly inaccurate within the database space. People need to look at the cost of the complete solution and not just a single component part in isolation to what is really required to meet the business requirement. Buying a single Hitachi Ultrastar 600GB 3.5” SAS 15Krpm hard disk drive will cost approximately £239.60 (http://scan.co.uk, 22nd March 2012) compared to an OCZ 600GB Z-Drive R4 CM84 PCIe costing £2,316.54 (http://scan.co.uk, 22nd March 2012); I’ve not included FusionIO ioDrive because there is no public pricing available for it – something I never understand and personally when companies do this I immediately think what are they hiding, luckily in FusionIO’s case the product is proven though is expensive compared to OCZ enterprise offerings. On the face of it the single 15Krpm hard disk has a price per GB of £0.39, the SSD £3.86; this is what you will see in the press and this is what sales people will use in comparing the two technologies – do not be fooled by this bullshit people! What is the requirement? The requirement is the database will have a static size of 400GB kept static through archiving so growth and trim will balance the database size, the client requires resilience, there will be several hundred call centre staff querying the database where queries will read a small amount of data but there will be no hot spot in the data so the randomness will come across the entire 400GB of the database, estimates predict that the IOps required will be approximately 4,000IOps at peak times, because it’s a call centre system the IO latency is important and must remain below 5ms per IO. The balance between read and write is 70% read, 30% write. The requirement is now defined and we have three of the most important pieces of the puzzle – space required, estimated IOps and maximum latency per IO. Something to consider with regard SQL Server; write activity requires synchronous IO to the storage media specifically the transaction log; that means the write thread will wait until the IO is completed and hardened off until the thread can continue execution, the requirement has stated that 30% of the system activity will be write so we can expect a high amount of synchronous activity. The hardware solution needs to be defined; two possible solutions: hard disk or solid state based; the real question now is how many hard disks are required to achieve the IO throughput, the latency and resilience, ditto for the solid state. Hard Drive solution On a test on an HP DL380, P410i controller using IOMeter against a single 15Krpm 146GB SAS drive, the throughput given on a transfer size of 8KiB against a 40GiB file on a freshly formatted disk where the partition is the only partition on the disk thus the 40GiB file is on the outer edge of the drive so more sectors can be read before head movement is required: For 100% sequential IO at a queue depth of 16 with 8 worker threads 43,537 IOps at an average latency of 2.93ms (340 MiB/s), for 100% random IO at the same queue depth and worker threads 3,733 IOps at an average latency of 34.06ms (34 MiB/s). The same test was done on the same disk but the test file was 130GiB: For 100% sequential IO at a queue depth of 16 with 8 worker threads 43,537 IOps at an average latency of 2.93ms (340 MiB/s), for 100% random IO at the same queue depth and worker threads 528 IOps at an average latency of 217.49ms (4 MiB/s). From the result it is clear random performance gets worse as the disk fills up – I’m currently writing an article on short stroking which will cover this in detail. Given the work load is random in nature looking at the random performance of the single drive when only 40 GiB of the 146 GB is used gives near the IOps required but the latency is way out. Luckily I have tested 6 x 15Krpm 146GB SAS 15Krpm drives in a RAID 0 using the same test methodology, for the same test above on a 130 GiB for each drive added the performance boost is near linear, for each drive added throughput goes up by 5 MiB/sec, IOps by 700 IOps and latency reducing nearly 50% per drive added (172 ms, 94 ms, 65 ms, 47 ms, 37 ms, 30 ms). This is because the same 130GiB is spread out more as you add drives 130 / 1, 130 / 2, 130 / 3 etc. so implicit short stroking is occurring because there is less file on each drive so less head movement required. The best latency is still 30 ms but we have the IOps required now, but that’s on a 130GiB file and not the 400GiB we need. Some reality check here: a) the drive randomness is more likely to be 50/50 and not a full 100% but the above has highlighted the effect randomness has on the drive and the more a drive fills with data the worse the effect. For argument sake let us assume that for the given workload we need 8 disks to do the job, for resilience reasons we will need 16 because we need to RAID 1+0 them in order to get the throughput and the resilience, RAID 5 would degrade performance. Cost for hard drives: 16 x £239.60 = £3,833.60 For the hard drives we will need disk controllers and a separate external disk array because the likelihood is that the server itself won’t take the drives, a quick spec off DELL for a PowerVault MD1220 which gives the dual pathing with 16 disks 146GB 15Krpm 2.5” disks is priced at £7,438.00, note its probably more once we had two controller cards to sit in the server in, racking etc. Minimum cost taking the DELL quote as an example is therefore: {Cost of Hardware} / {Storage Required} £7,438.60 / 400 = £18.595 per GB £18.59 per GiB is a far cry from the £0.39 we had been told by the salesman and the myth. Yes, the storage array is composed of 16 x 146 disks in RAID 10 (therefore 8 usable) giving an effective usable storage availability of 1168GB but the actual storage requirement is only 400 and the extra disks have had to be purchased to get the  IOps up. Solid State Drive solution A single card significantly exceeds the IOps and latency required, for resilience two will be required. ( £2,316.54 * 2 ) / 400 = £11.58 per GB With the SSD solution only two PCIe sockets are required, no external disk units, no additional controllers, no redundant controllers etc. Conclusion I hope by showing you an example that the myth that hard disk drives are cheaper per GiB than Solid State has now been dispelled - £11.58 per GB for SSD compared to £18.59 for Hard Disk. I’ve not even touched on the running costs, compare the costs of running 18 hard disks, that’s a lot of heat and power compared to two PCIe cards!Just a quick note: I've left a fair amount of information out due to this being a blog! If in doubt, email me :)I'll also deal with the myth that SSD's wear out at a later date as well - that's just way over done still, yes, 5 years ago, but now - no.

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