Search Results

Search found 6770 results on 271 pages for 'azure storage'.

Page 249/271 | < Previous Page | 245 246 247 248 249 250 251 252 253 254 255 256  | Next Page >

• How to make chrome.tabs.update works with content script

  - by user1673772

  I work on a little extension on Google Chrome, I want to create a new tab, go on the url "sample"+i+".com", launch a content script on this url, update the current tab to "sample"+(i+1)+".com", and launch the same script. I looked the Q&A available on stackoverflow and I google it but I didn't found a solution who works. This is my actually code of background.js (it works), it creates two tabs (i=21 and i=22) and load my content script for each url, when I tried to do a chrome.tabs.update Chrome launchs directly a tab with i = 22 (and the script works only one time) : function extraction(tab) { for (var i =21; i<23;i++) { chrome.storage.sync.set({'extraction' : 1}, function() {}); //for my content script chrome.tabs.create({url: "http://example.com/"+i+".html"}, function() {}); } } chrome.browserAction.onClicked.addListener(function(tab) {extraction(tab);}); If anyone can help me, the content script and manifest.json are not the problem. I want to make that 15000 times so I can't do otherwise. Thank you.

  Read the article

• What kind of online hosting do I need for a WCF-based service?

  - by mafutrct

  First of all, I'm not sure if SO is the right place to ask. Please migrate me if needed. I would like to host a WCF-based service so it is available for everyone. While hosting it on my personal, local servers succeeded, I would prefer to move it to an external service provider for various reasons. I'll be blunt: I have no clue about hosting providers. I know there are webhosters, virtual and root servers and several other services. What I would like to know is what kind of hosting I need in my case. I understand that a root server would easily fulfill my requirements, but that is not exactly cheap. The program I'd like to run on the server requires .NET 4, preferably on a windows machine. Access to a folder in the file system is much appreciated (1 GB storage is enough by far). Communication with clients (in form of an applications written in .NET) via opening a port on the server. Traffic is low (<<1 GB/month?) There is no website. Having the provider perform updates would be nice. My understanding is that a virtual server would be a possible solution. Prices seem start at around 5€/month, which is ok for me. However, I read that for these cheap solutions RAM is severely limited (~400 MB), and I'm not confident that is enough to run windows and a .NET application.

  Read the article

• JS: Storing dynamic variables across pages?

  - by user2467599

  I've been looking into local storage options and plugins like Persist.js, sessvars.js, and even sisyphus.js - but I am unsure if any are the best fit (though I'm fairly certain I need to use one). Page one is a form with input fields for data like names, phones, and email. I have a button that replicates a wrapper div (and it's inputs) as long as more inputs are needed. When the form is filled the user hits submit which takes them to a 'confirmation' type php page. I need to the give the user an 'edit' button on page 2 that takes them back to page 1 and leaves all the info alone. For the most part everything returns fine, but if the user had hit the 'replicate' button before submission, and then hits edit afterwards, all the inputs that were dynamically generated return empty and the div no longer exists. Someone suggested that my variables are not persistent (when the replicate button is hit, input with an id="name1" becomes "name2" and so on) so that's when I found out about the plugins mentioned before. Is there a way that I can implement one of those plugins (or any other method) so that when the user returns to page one the div and it's input values remain unchanged? And if I'm on the right track are there any examples?

  Read the article

• How do I display core data on second view controller?

  - by jon

  I am working on my first core data iPhone application. I am using a navigation controller, and the root view controller displays 4 rows. Clicking the first row takes me to a second table view controller. However, when I click the back button, repeat the row tap, click the back button again, and tap the row a third time, I get an error. I have been researching this for a week with no success. I can reproduce the error easily: Create a new Navigation-based Application, use Core Data for storage, call it MyTest which creates MyTestAppDelegate and RootViewController. Add new UIViewController subclass, with UITableViewController and xib, call it ListViewController. Copy code from RootViewController.h and .m to ListViewController.h and .m., changing the file names appropriately. To simplify the code, I removed the trailing “_” from all variables. In RootViewController, I added #import ListViewController.h, set up an array to display 4 rows and navigate to ListViewController when clicking the first row. In ListViewController.m, I added #import MyTestAppDelegate.h” and the following code: - (void)viewDidLoad { [super viewDidLoad]; if (managedObjectContext == nil) { managedObjectContext = [(MyTestAppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext]; } .. } The sequence that causes the error is tap row, return, tap row, return, tap row - error. managedObjectContext is synthesized for the third time. I appreciate your patience and your help, as this makes no sense to me. ADDENDUM: I may have a partial solution. http://www.iphonedevsdk.com/forum/iphone-sdk-development/41688-accessing-app-delegates-managed-object-context.html If I do not release the managedObjectContext in the .m file, the error goes away. Is that ok or will that cause me issues? - (void)dealloc { [fetchedResultsController release]; // [managedObjectContext release]; [super dealloc]; } ADDENDUM 2: See solution below. Sorry for the formatting issues - this was my first post.

  Read the article

• How do I implement IEnumerable?

  - by Stacey

  I have a class that contains a static number of objects. This class needs to be frequently 'compared' to other classes that will be simple List objects. public partial class Sheet { public Item X{ get; set; } public Item Y{ get; set; } public Item Z{ get; set; } } the items are obviously not going to be "X" "Y" "Z", those are just generic names for example. The problem is that due to the nature of what needs to be done, a List won't work; even though everything in here is going to be of type Item. It is like a checklist of very specific things that has to be tested against in both code and runtime. This works all fine and well; it isn't my issue. My issue is iterating it. For instance I want to do the following... List<Item> UncheckedItems = // Repository Logic Here. UncheckedItems contains all available items; and the CheckedItems is the Sheet class instance. CheckedItems will contain items that were moved from Unchecked to Checked; however due to the nature of the storage system, items moved to Checked CANNOT be REMOVED from Unchecked. I simply want to iterate through "Checked" and remove anything from the list in Unchecked that is already in "Checked". So naturally, that would go like this with a normal list. foreach(Item item in Unchecked) { if( Checked.Contains(item) ) Unchecked.Remove( item ); } But since "Sheet" is not a 'List', I cannot do that. So I wanted to implement IEnumerable so that I could. Any suggestions? I've never implemented IEnumerable directly before and I'm pretty confused as to where to begin.

  Read the article

• How do I deal with different requests that map to the same response?

  - by daxim

  I'm designing a Web service. The request is idempotent, so I chose the GET method. The response is relatively expensive to calculate and not small, so I want to get caching (on the protocol level) right. (Don't worry about memoisation at my part, I have that already covered; my question here is actually also paying attention to the Web as a whole.) There's only one mandatory parameter and a number of optional parameter with default values if missing. For example, the following two map to the same representation of the response. (If this is a dumb way to go about it the interface, propose something better.) GET /service?mandatory_parameter=some_data HTTP/1.1 GET /service?mandatory_parameter=some_data;optional_parameter=default1;another_optional_parameter=default2;yet_another_optional_parameter=default3 HTTP/1.1 However, I imagine clients do not know this and would treat them separate and therefore waste cache storage. What should I do to avoid violating the golden rule of caching? Make up a canonical form, document it (e.g. all parameters are required after all and need to be sorted in a specific order) and return a client error unless the required form is met? Instead of an error, redirect permanently to the canonical form of a request? Or is it enough to not mind how the request looks like, and just respond with the same ETag for same responses?

  Read the article

• Java - multithreaded access to a local value store which is periodically cleared

  - by Telax

  I'm hoping for some advice or suggestions on how best to handle multi threaded access to a value store. My local value storage is designed to hold onto objects which are currently in use. If the object is not in use then it is removed from the store. A value is pumped into my store via thread1, its entry into the store is announced to listeners, and the value is stored. Values coming in on thread1 will either be totally new values or updates for existing values. A timer is used to periodically remove any value from the store which is not currently in use and so all that remains of this value is its ID held locally by an intermediary. Now, an active element on thread2 may wake up and try to access a set of values by passing a set of value IDs which it knows about. Some values will be stored already (great) and some may not (sadface). Those values which are not already stored will be retrieved from an external source. My main issue is that items which have not already been stored and are currently being queried for may arrive in on thread1 before the query is complete. I'd like to try and avoid locking access to the store whilst a query is being made as it may take some time.

  Read the article

• Variable Scoping in a method and its persistence in C++

  - by de costo

  Consider the following public method that adds an integer variable to a vector of ints(private member) in a class in C++. KoolMethod() { int x; x = 10; KoolList.Add(x); } Vector<int>KoolList; But is this a valid addition to a vector ??? Upon calling the method, it creates a local variable. The scope of this local variable ends the moment the execution control leaves the method. And since this local variable is allocated on a stack(on the method call), any member of KoolList points to an invalid memory location in deallocated stack which may or may not contain the expected value of x. Is this an accurate description of above mechanism ?? Is there a need for creating an int in heap storage using "new" operator everytime a value needs to be added to the vector like described below ????: KoolMethod() { int *x = new int(); *x = 10; KoolList.Add(x); } Vector<int*>KoolList;

  Read the article

• How to store and synchronize a big list of strings

  - by Joel

  I have a large database table in SQLExpress on Windows, with a particular field of interest 'code'. I have an Apache web server with MySQL on Linux. The web application on the Linux box needs access to the list of all codes. The only thing it will use the list for is checking for the existence of a given code. Having the Linux server call out to the Windows server is impractical as the Windows server is behind a NAT'ed office internet connection, and it may not always be accessible. I have set it so the Windows server will push the list of codes to the web server by means of a simple HTTP POST request. However, at this point I have not implemented the storage of the codes on the Linux box. Should I store them in a MySQL table with a single field 'code'? Then I get fast indexed lookups O(1), however I think synchronization will be an issue - given an updated list of codes, pushed from the Windows box, how would I optimally synchronize the list with the database? TRUNCATE, followed by INSERT? Should I instead store them in a flat file? Then I have O(n) look up time rather than O(1). Additionally an extra constant-time overhead too, as I will be processing the file in Ruby. However, synchronization is easy - simply replace the file.

  Read the article

• SQL Server: Why use shorter VARCHAR(n) fields?

  - by chryss

  It is frequently advised to choose database field sizes to be as narrow as possible. I am wondering to what degree this applies to SQL Server 2005 VARCHAR columns: Storing 10-letter English words in a VARCHAR(255) field will not take up more storage than in a VARCHAR(10) field. Are there other reasons to restrict the size of VARCHAR fields to stick as closely as possible to the size of the data? I'm thinking of Performance: Is there an advantage to using a smaller n when selecting, filtering and sorting on the data? Memory, including on the application side (C++)? Style/validation: How important do you consider restricting colunm size to force non-sensical data imports to fail (such as 200-character surnames)? Anything else? Background: I help data integrators with the design of data flows into a database-backed system. They have to use an API that restricts their choice of data types. For character data, only VARCHAR(n) with n <= 255 is available; CHAR, NCHAR, NVARCHAR and TEXT are not. We're trying to lay down some "good practices" rules, and the question has come up if there is a real detriment to using VARCHAR(255) even for data where real maximum sizes will never exceed 30 bytes or so. Typical data volumes for one table are 1-10 Mio records with up to 150 attributes. Query performance (SELECT, with frequently extensive WHERE clauses) and application-side retrieval performance are paramount.

  Read the article

• Getting my string value from my form into my class( not another form)

  - by jovany

  Hello all, I have a question regarding the some data which is being transfered from one form to my class. It's not going quite the way i'd like to , so I figured maybe there is someone who could help me. This is my code in my class Public Class DrawableTextBox Inherits Drawable Dim i_testString As Integer Private s_InsertLabel As String Private drawFont As Font Public Sub New(ByVal fore_color As Color, ByVal fill_color As Color, Optional ByVal line_width As Integer = 0, Optional ByVal new_x1 As Integer = 0, Optional ByVal new_y1 As Integer = 0, Optional ByVal new_x2 As Integer = 1, Optional ByVal new_y2 As Integer = 1) MyBase.New(fore_color, fill_color, line_width) X1 = new_x1 Y1 = new_y1 X2 = new_x2 Y2 = new_y2 Trace.WriteLine(s_InsertLabel) End Sub Friend WriteOnly Property _textBox() As String Set(ByVal Value As String) s_InsertLabel = Value Trace.WriteLine(s_InsertLabel) End Set End Property ' Draw the object on this Graphics surface. Public Overrides Sub Draw(ByVal gr As System.Drawing.Graphics) ' Make a Rectangle representing this rectangle. Dim rect As Rectangle = GetBounds() ' Fill the rectangle as usual. Dim fill_brush As New SolidBrush(FillColor) gr.FillRectangle(fill_brush, rect) fill_brush.Dispose() ' See if we're selected. If IsSelected Then ' Draw the rectangle highlighted. Dim highlight_pen As New Pen(Color.Yellow, LineWidth) gr.DrawRectangle(highlight_pen, rect) highlight_pen.Dispose() ' Draw grab handles. Trace.WriteLine("drawing the lines for my textbox") DrawGrabHandle(gr, X1, Y1) DrawGrabHandle(gr, X1, Y2) DrawGrabHandle(gr, X2, Y2) DrawGrabHandle(gr, X2, Y1) Else 'TextBox() Dim fg_pen As New Pen(Color.Red, LineWidth) 'Dim fontSize As Single = 0.1 + ((Y2 - Y1) / 2) Dim fontSize As Single = 20 Try Dim drawFont As New Font("Arial", fontSize, FontStyle.Bold) Trace.WriteLine(s_InsertLabel) gr.DrawString(s_InsertLabel, drawFont, Brushes.Brown, X1, Y1) Catch ex As ArgumentException End Try gr.DrawRectangle(Pens.Azure, rect) ' gr.DrawRectangle(fg_pen, rect) fg_pen.Dispose() End If End Sub Public Function GetValueString(ByVal ValueType As String) Return ValueType End Function ' Return the object's bounding rectangle. Public Overrides Function GetBounds() As System.Drawing.Rectangle Return New Rectangle( _ Min(X1, X2), _ Min(Y1, Y2), _ Abs(100), _ Abs(30)) Trace.WriteLine("don't forget to make variables in GetBounds DrawableTextbox") End Function ' Return True if this point is on the object. Public Overrides Function IsAt(ByVal x As Integer, ByVal y As Integer) As Boolean Return (x >= Min(X1, X2)) AndAlso _ (x <= Max(X1, X2)) AndAlso _ (y >= Min(Y1, Y2)) AndAlso _ (y <= Max(Y1, Y2)) End Function ' Move the second point. Public Overrides Sub NewPoint(ByVal x As Integer, ByVal y As Integer) X2 = x Y2 = y End Sub ' Return True if the object is empty (e.g. a zero-length line). Public Overrides Function IsEmpty() As Boolean Return (X1 = X2) AndAlso (Y1 = Y2) End Function End Class I've got a form with a textbox( form1) in which the text is being inserted and passed through a buttonclick (al via properties). As you can see I've placed several traces and in the property of the class my trace works fine , however if I look in my Draw function it is already gone. And I get a blank trace. Does anyone know what's happening here. thanks in advance. (forgive me I'm new )

  Read the article

• BIOS upgrade lowers CPU temperature

  - by N.N.

  Setup I've got a system with an Asus P8Z68-V PRO motherboard and an Intel Core i7-2600K CPU running at stock speed (no overlocking) which I cool with a Noctua NH-U12P. On the heatsink I've got the two included fans connected via the included Low-Noise Adapters (L.N.A.) 1100 RPM, 16.9 dB(A). In the BIOS settings I've set the CPU and chassis fan profile to silent. Issue Yesterday I upgraded from BIOS version 0501 to 0606. After the upgrade I checked the temperatures in the BIOS monitor and was surprised to see that the CPU temperature was slightly ~30°C. Before the upgrade the CPU temperature was ~50°C with the same BIOS settings (see the following heading for details on temperatures). How can this be? It seems a bit odd that a BIOS upgrade can lower the CPU temperature by 20°C and it also seems odd that the CPU temperature is lower than the chassis temperature. Temperatures When I've checked temperatures the room temperature has been ~23°C. I haven't changed the placement of the computer nor the hardware or cooling setup between BIOS versions. BIOS version 0501 BIOS monitor: CPU: ~50°C Chassis: ~33°C I haven't got any temperature measures from lm-sensors or the like for version 0501 because I only discovered the issue after upgrading to version 0606 and the BIOS updater utility won't let me downgrade to version 0501 (it says "outdated image" when I try to load version 0501). BIOS version 0606 BIOS monitor: CPU: ~30°C Chassis: ~33°C lm-sensors in Ubuntu 11.04 Desktop 64-bit (sudo sensors after an uptime of 4 h 52 min and a load average of 0.22, 0.18, 0.15): coretemp-isa-0000 Adapter: ISA adapter Core 0: +32.0°C (high = +80.0°C, crit = +98.0°C) coretemp-isa-0001 Adapter: ISA adapter Core 1: +35.0°C (high = +80.0°C, crit = +98.0°C) coretemp-isa-0002 Adapter: ISA adapter Core 2: +29.0°C (high = +80.0°C, crit = +98.0°C) coretemp-isa-0003 Adapter: ISA adapter Core 3: +36.0°C (high = +80.0°C, crit = +98.0°C) The BIOS monitor temperatures was checked directly after the lm-sensors temperatures was checked. BIOS version 0706, 0801, 1101 and 3203 I get the same kind of temperatures both in the BIOS monitor and with lm-sensors in BIOS version 0706, 0801, 1101 and 3203 as in 0606. Information from Asus The 0606 changelog mentions nothing explicitly about CPU temperature (but item 3., as indicated by sidran32, might affect temperatures): P8Z68-V PRO 0606 BIOS with IRST 10.6.0.1002 Enable the support of Intel Rapid Storage Technology version 10.6.0.1002 Release Improve DRAM compatibility Improve System stability Improve compatibility with some Raid card model Increase IGD share memory size to 512MB However the following FAQ might give a hint: FAQs I find that the CPU temperature reading in BIOS is about 10~20 degrees centigrade hotter than the reading in OS. Is it normal? Page Tools Solution That is normal as BIOS does not send idle command to the CPU, making most of the power saving features useless. You should be getting similar reading if you disable EIST/C1E/CPU C3 Report/CPU C6 Report in BIOS.

  Read the article

• Simple Backup Strategy for Amazon EC2 instances / volumes?

  - by minerj

  You have entered Introductory Backups for Amazon EC2 EBS-backed Windows Images 010... I have been browsing my brains out to find a simple backup strategy for our single windows 2008 server running SharePoint Services. This is an EBS-backed image of one server with one data volume. I don’t need anything exotic. I only need a “daily” backup (losing a day’s worth of data is not catastrophic). We have created and saved an EBS backed AMI image (Windows 2008) we are comfortable using. We started off making backups by simply creating a new EBS AMI image. This is really simple, but the running server is put offline during the first 10 – 15 minutes of creating the image – not ideal. The standard way of creating backups would seem to be creating snapshots of volumes attached to a running instance. Again it’s pretty simple and the server remains usable during the snapshot generation. The apparent Catch-22 is that you can’t simply launch a new instance directly from a snapshot. I know how to bundle a running instance to S3 storage and then register the AMI from the S3 bucket. This does allow me to capture a backup of a running instance and, if the running instance is lost, register the AMI from the S3 bucket and launch the new AMI to recover the instance, but this seems really convoluted and it seems ridiculous to have to juggle back and forth between the AWS Console and the S3 Organizer plug-in for Firefox to get this accomplished. (Please don't mention the command line approach, this is an 010 level course). From playing around with EBS-backed images, the following approach appears to work for me (all done within the AWS Console): 1.For your backups, simply snapshot the system volume (/dev/sda1) as needed. 2.If you lose your running instance, do the following: a.Create a new volume from your last snapshot backup b.Launch another instance of your starting AMI (must be EBS-backed) c.Stop this instance. d.Detach the existing system volume from the new stopped instance and discard. e.Attach the newly created volume as system volume (/dev/sda1) to the stopped instance. f.Re-start the new instance. I have tested this out a couple of times and it seems to work for me. Question: Is there anything wrong with this approach?

  Read the article

• vSphere Client vCenter Template Customization Specification Using Windows Sysprep Unattended Answer XML File

  - by Brian

  I'm trying to setup a vSphere Client vCenter v5.0.0 Build 455964 Template Customization Specification using a Windows Sysprep unattended answer XML file for Win2008R2. However I didn't know how Sysprep worked before attempting this so it was a time-consuming nightmare (even after reviewing VMware vSphere ESXi 5's documentation)! I think I've figure out what I'm supposed to be doing, but it's still not working. The biggest problem at this point is that vSphere Client vCenter Customization Specification IP address information is not sticking when I load a Sysprep XML file with just 1 basic setting! This can only be a bug. Here is the process I'm using: PROCESS for Windows - vSphere Client Install Windows OS install VM Tools customize Windows (GPOs can be used to do this after deployment) install Applications (GPOs can be used to do this after deployment too) shutdown the VM convert the VM to a template create a custom Windows Sysprep XML answer file with desired customizations View Management Customization Specifications Manager create "New" Specification for "Target Virtual Machine OS" select Windows check "Use Custom Sysprep Answer File" (ADDS: Custom Sysprep File. KEEPS: Network (IP), Operating System Options (SID, Sysprep /generalize). REPLACES: Registration Information of Owner Name & Organization, Computer Name, Windows License (Key), Administrator Password, Time Zone, Run Once, Workgroup or Domain) name it as "VMwareCS-OS####R#x32/64w/Sysprep-TEST" (CS=Customization Specification) set Description as "Created YYYY/MM/DD by FLast" NEXT import a Sysprep answer file from secure location NEXT Custom settings NEXT click "..." box to right of "Use DHCP" set "Use the following IP settings:" for "IP Address" fill out the first 2 octets set appropriate values for other 2-3 fields set DNS server addresses OK NEXT check "Generate New Security ID (SID)" ALWAYS as template is likely a domain-member computer so it can be updated occasionally NEXT Finish View Inventory VMs and Templates right-click previously completed template Deploy Virtual Machine from this Template provide the new OS name (max15char) select inventory location NEXT select Host/Cluster (wait for validation to succeed) NEXT select Resource Pool (wait for validation to succeed) NEXT select Storage location NEXT check "Power on this virtual machine after creation" select "Customize using an existing customization specification" select desired specification select "Use the Customization Wizard to temporarily adjust the specification before deployment" NEXT NEXT Custom settings? NEXT check "Generate New Security ID (SID)" ALWAYS as template is likely a domain-member computer so it can be updated occasionally NEXT Finish Finish. I know a community member named "brian" (http://serverfault.com/users/25904/brian) has worked with this scenario before, but I couldn't figure out how to contact him directly, so Brian if you see this message could you provide some information to help? Thanks, Brian

  Read the article

• Linux HA cluster w/Xen, Heartbeat, Pacemaker. domU does not failover to secondary node

  - by Kendall

  I am having the followig problem with an OenSuSE + Heartbeat + Pacemaker + Xen HA cluster: when the node a Xen domU is running on is "dead" the Xen domU running on it is not restarted on the second node. The cluster is setup with two nodes, each running OpenSuSE-11.3, Heartbeat 3.0, and Pacemaker 1.0 in CRM mode. For storage I am using a LUN on an iSCSI SAN device; the LUN is formatted with OCFS2 and managed with LVM. The Xen domU has two logical volumes; one for root and the other for swap. I am using IPMI cards for STONITH devices, and a dedicated ethernet link for heartbeat communications. The ha.cf file is as follows: keepalive 1 deadtime 10 warntime 5 udpport 694 ucast eth1 auto_failback off node dhcp-166 node stage use_logd yes crm yes My resources look as follows: shocrm(live)configure# show node $id="5c1aa924-bba4-4f95-a367-6c9a58ac4a38" dhcp-166 node $id="cebc92eb-af24-4833-aaf0-672adf80b58e" stage primitive Xen-Util ocf:heartbeat:Xen \ meta target-role="Started" \ operations $id="Xen-Util-operations" \ op start interval="0" timeout="60" start-delay="0" \ op stop interval="0" timeout="120" \ params xmfile="/etc/xen/vm/xen-util" primitive my-stonith stonith:external/ipmi \ params hostname="dhcp-166" ipaddr="192.168.3.106" userid="ADMIN" passwd="xxx" \ op monitor interval="2m" timeout="60s" primitive my-stonith2 stonith:external/ipmi \ params hostname="stage" ipaddr="192.168.3.105" userid="ADMIN" passwd="xxx" \ op monitor interval="2m" timeout="60s" property $id="cib-bootstrap-options" \ dc-version="1.0.9-89bd754939df5150de7cd76835f98fe90851b677" \ cluster-infrastructure="Heartbeat" The Xen domU config file is as follows: name = "xen-util" bootloader = "/usr/lib/xen/boot/domUloader.py" #bootargs = "xvda1:/vmlinuz-xen,/initrd-xen" bootargs = "--entry=xvda1:/boot/vmlinuz-xen,/boot/initrd-xen" memory = 4096 disk = [ 'phy:vg_xen/xen-util-root,xvda1,w', 'phy:vg_xen/xen-util-swap,xvda2,w', ] root = "/dev/xvda1" vif = [ 'mac=00:16:3e:42:42:06' ] #vfb = [ 'type=vnc,vncunused=0,vnclisten=192.168.3.172' ] extra = "" Say domU "Xen-Util" is running on node "stage"; if "stage" goes down, "Xen-Util" does not restart on node "dhcp-166". It seems to want to try as an "xm list" will show it for a few seconds and if you "xm console xen-util" it will give a message like "copying /boot/kernel.gz from xvda1 to /var/lib/xen/tmp/kernel.a53gs for booting". However, it never gets past that, eventually gives up, and no longer appears in "xm list". Now, when node "stage" comes back online after being power cycled, it detects that "Xen-Util" isn't running, and starts it (on stage). I've tried starting "Xen-Util" on node "dhcp-166" without the cluster running, and it works fine. No problems. So, I know it works in that respect. Any ideas? Thanks!

  Read the article

• Benchmarking hosting providers IO with Bonnie

  - by Derek Organ

  Ok, because of a bunch of projects I'm working on I've access to dedicated Servers on a 3 hosting providers. As an experiment and for educational purposes I decided to see if I could benchmark how good the IO is with each. Bit of research lead me to Bonnie++ So I installed it on the server and ran this simple command /usr/sbin/bonnie -d /tmp/foo The 3 machines in different hosting providers are all dedicated machines, one is a VPS, other two are on some cloud platform e.g. VMWare / Xen using some kind of clustered SAN for storage This might be a naive thing to do but here are the results I found. HOST A Version 1.03c ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP xxxxxxxxxxxxxxxx 1G 45081 88 56244 14 19167 4 20965 40 67110 6 67.2 0 ------Sequential Create------ --------Random Create-------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 15264 28 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ xxxxxxxx,1G,45081,88,56244,14,19167,4,20965,40,67110,6,67.2,0,16,15264,28,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++ HOST B Version 1.03d ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP xxxxxxxxxxxx 4G 43070 91 64510 15 19092 0 29276 47 39169 0 448.2 0 ------Sequential Create------ --------Random Create-------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 24799 52 +++++ +++ +++++ +++ 25443 54 +++++ +++ +++++ +++ xxxxxxx,4G,43070,91,64510,15,19092,0,29276,47,39169,0,448.2,0,16,24799,52,+++++,+++,+++++,+++,25443,54,+++++,+++,+++++,+++ HOST C Version 1.03c ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP xxxxxxxxxxxxx 1536M 15598 22 85698 13 258969 20 16194 22 723655 21 +++++ +++ ------Sequential Create------ --------Random Create-------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 14142 22 +++++ +++ 18621 22 13544 22 +++++ +++ 17363 21 xxxxxxxx,1536M,15598,22,85698,13,258969,20,16194,22,723655,21,+++++,+++,16,14142,22,+++++,+++,18621,22,13544,22,+++++,+++,17363,21 Ok, so first off what is the best way to read the figures and are there any issues with really comparing these numbers? Is this in any way a true representation of IO Speed? If not is there any way for me to test that? Note: these 3 machines are using either Ubuntu or Debian (I presume that doesn't really matter)

  Read the article

• ESXi 5.1 ghettoVCB stuck at Clone: 10% done

  - by stormdrain

  Trying to run ghettoVCB for the first time here. I am using a NAS that is set up as a datastore on the host. I did a dry run and it completed without error. The VM is ~500GB and there is only one on the host that I'm trying to backup. I proceeded to start the actual backup: ./ghettoVCB.sh -m vmname -g ghettoVCB.conf It goes though the config and looks like it's taking off: 2013-10-24 11:43:19 -- info: CONFIG - USING GLOBAL GHETTOVCB CONFIGURATION FILE = ghettoVCB.conf 2013-10-24 11:43:19 -- info: CONFIG - VERSION = 2013_01_11_0 2013-10-24 11:43:19 -- info: CONFIG - GHETTOVCB_PID = 17398616 2013-10-24 11:43:19 -- info: CONFIG - VM_BACKUP_VOLUME = /vmfs/volumes/nas2tb-001/esxi4 2013-10-24 11:43:19 -- info: CONFIG - VM_BACKUP_ROTATION_COUNT = 3 2013-10-24 11:43:19 -- info: CONFIG - VM_BACKUP_DIR_NAMING_CONVENTION = 2013-10-24_11-43-18 2013-10-24 11:43:19 -- info: CONFIG - DISK_BACKUP_FORMAT = thin 2013-10-24 11:43:19 -- info: CONFIG - POWER_VM_DOWN_BEFORE_BACKUP = 0 2013-10-24 11:43:19 -- info: CONFIG - ENABLE_HARD_POWER_OFF = 0 2013-10-24 11:43:19 -- info: CONFIG - ITER_TO_WAIT_SHUTDOWN = 4 2013-10-24 11:43:19 -- info: CONFIG - POWER_DOWN_TIMEOUT = 5 2013-10-24 11:43:19 -- info: CONFIG - SNAPSHOT_TIMEOUT = 15 2013-10-24 11:43:19 -- info: CONFIG - LOG_LEVEL = info 2013-10-24 11:43:19 -- info: CONFIG - BACKUP_LOG_OUTPUT = /tmp/ghettoVCB-2013-10-24_11-43-18-17398616.log 2013-10-24 11:43:19 -- info: CONFIG - ENABLE_COMPRESSION = 0 2013-10-24 11:43:19 -- info: CONFIG - VM_SNAPSHOT_MEMORY = 0 2013-10-24 11:43:19 -- info: CONFIG - VM_SNAPSHOT_QUIESCE = 0 2013-10-24 11:43:19 -- info: CONFIG - ALLOW_VMS_WITH_SNAPSHOTS_TO_BE_BACKEDUP = 0 2013-10-24 11:43:19 -- info: CONFIG - VMDK_FILES_TO_BACKUP = all 2013-10-24 11:43:19 -- info: CONFIG - VM_SHUTDOWN_ORDER = 2013-10-24 11:43:19 -- info: CONFIG - VM_STARTUP_ORDER = 2013-10-24 11:43:19 -- info: CONFIG - EMAIL_LOG = 0 2013-10-24 11:43:19 -- info: 2013-10-24 11:43:22 -- info: Initiate backup for vmname 2013-10-24 11:43:22 -- info: Creating Snapshot "ghettoVCB-snapshot-2013-10-24" for serv2 Destination disk format: VMFS thin-provisioned Cloning disk '/vmfs/volumes/esxi4-storage/vmname/vmname_1.vmdk'... Clone: 10% done. and it's been that way for over an hour now. Stuck at Clone: 10% done.. Thing is: I can see the vmdk on the NAS. And it looks like almost the whole thing is there. On the NAS it's showing ~430GB but on vSphere Client Summary is shows as 507GB. I don't see the vmdk on the NAS growing any more. The logfile mimics some of the above and is sitting at "Creating Snapshot..." and nothing else is coming in. Is the vmdk on the NAS showing all those GB because of the provisioning or something? i.e. is the size of the file not necessarily indicative of the amount of actual data that has been copied? Is there are reason it might be "Stuck" at 10%? i.e. could it really be taking this long? Any other tips? Thanks. Edit: as soon as I hit the Submit button, I glance over to see that it has incremented to 11% done. Good to know it'll be complete sometime around when the sun explodes.

  Read the article

• kernel panic after LVM setup

  - by Manuel Sopena Ballesteros

  I broke my webserver... My setup is: VMWare ESXi environemt CPanel installed CentOS release 6.5 (Final) 4 CPUs 2G RAM 2x VM disks 100G each LVM system This was my previous storage settings (the server was working fine at this time): # df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg_test01-lv_root 95G 1.4G 88G 2% / tmpfs 939M 0 939M 0% /dev/shm /dev/sdb1 99G 188M 94G 1% /tmp /dev/sda1 485M 54M 407M 12% /boot My web developer asked me to merge /tmp and / disks so this is what I did: Delete /dev/sdb1 partition using fdisk Create a new partition as LVM on /dev/sdb1 using fdisk Create a new physical volume -- pvcreate /dev/sdb1 Extend volume group -- vgextend /dev/sdb1 vg_test01 Extend logical volume -- lvextend -l +100%FREE /dev/vg_test01/lv_root Resize filesystem -- resize2fs /dev/vg_test01/lv_root This is the new configuration: # df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg_test01-lv_root 213G 105G 97G 52% / tmpfs 939M 0 939M 0% /dev/shm /dev/sda1 485M 54M 407M 12% /boot /usr/tmpDSK 4.0G 145M 3.6G 4% /tmp Since I have the new settings my web server is throwing kernel panics quite often (around every 2 days). The message says: INFO: task <taskName>:<pid> blocked for more than 120 seconds. The list of process affected that I can see from the console are: mysqld queueprocd httpd suphp vmtoolsd loop0 auditd The only way I can fix this is reseting (cold reboot) the VM. I don't think it is a hardware issue as sar is not showing any bottleneck: Linux 2.6.32-431.3.1.el6.x86_64 (test01) 08/22/2014 _x86_64_ (4 CPU) 12:00:01 AM CPU %user %nice %system %iowait %steal %idle 12:10:01 AM all 26.86 0.01 0.98 0.57 0.00 71.57 12:20:01 AM all 1.78 0.02 1.03 0.08 0.00 97.09 12:30:01 AM all 26.34 0.02 0.85 0.05 0.00 72.74 12:40:01 AM all 27.12 0.01 1.11 1.22 0.00 70.54 12:50:01 AM all 1.59 0.02 0.94 0.13 0.00 97.32 01:00:01 AM all 26.10 0.01 0.77 0.04 0.00 73.07 01:10:01 AM all 27.51 0.01 1.16 0.14 0.00 71.18 01:20:01 AM all 1.80 0.07 1.06 0.08 0.00 96.99 01:30:01 AM all 26.19 0.01 0.78 0.05 0.00 72.96 01:40:01 AM all 26.62 0.02 0.87 0.05 0.00 72.45 01:50:02 AM all 1.35 0.01 0.87 0.02 0.00 97.75 02:00:01 AM all 26.11 0.02 0.69 0.02 0.00 73.17 02:10:01 AM all 26.73 0.02 0.89 0.14 0.00 72.21 02:20:01 AM all 1.45 0.01 0.92 0.04 0.00 97.58 02:30:01 AM all 26.59 0.01 1.06 0.03 0.00 72.31 02:40:01 AM all 26.27 0.01 0.72 0.05 0.00 72.95 02:50:01 AM all 0.86 0.01 0.50 0.09 0.00 98.53 03:00:01 AM all 25.61 0.02 0.39 0.03 0.00 73.96 03:10:01 AM all 26.30 0.08 0.66 0.14 0.00 72.82 03:20:01 AM all 0.81 0.01 0.51 0.04 0.00 98.63 03:30:02 AM all 26.15 0.02 0.53 0.07 0.00 73.24 03:40:01 AM all 26.06 0.01 0.47 0.04 0.00 73.42 03:50:01 AM all 0.96 0.02 0.51 0.03 0.00 98.48 Average: all 17.69 0.02 0.79 0.14 0.00 81.36 06:58:14 AM LINUX RESTART 07:00:01 AM CPU %user %nice %system %iowait %steal %idle 07:10:01 AM all 1.04 0.02 0.57 0.95 0.00 97.42 07:20:02 AM all 0.66 0.01 0.39 0.06 0.00 98.87 07:30:01 AM all 25.71 0.01 0.45 0.16 0.00 73.67 07:40:01 AM all 25.88 0.01 0.35 0.08 0.00 73.68 07:50:01 AM all 1.13 0.02 0.55 0.11 0.00 98.19 As you can see the server became unresponsive at 03.50 AM and I had to reset the VM at 06.58 AM to bring the website up again. I would appreciate any help/assistance to fix this issue. thank you very much

  Read the article

• How to diagnose repeated "Starting up database '<dbname>'"

  - by Richard Slater

  I have a SQL 2008 server which is predominantly used as a development server, in the last two weeks it has been having occasional "fits", I have isolated the cause of these fits as CHECKDB being run almost continuiously, the following log information is logged to the Windows Event Log (Source: MSSQLSERVER, Category: Server): Event: 1073758961, Message: Starting up database 'DBName1'. Event: 1073758961, Message: Starting up database 'DBName2'. Event: 1073759397, Message: CHECKDB for database 'DBName1' finished without errors on 2010-07-19 20:29:26.993 (local time). This is an informational message only; no user action is required. Event: 1073759397, Message: CHECKDB for database 'DBName1' finished without errors on 2010-07-19 20:29:26.993 (local time). This is an informational message only; no user action is required. This is repeated every 1-2 seconds untill SQL Server is restarted or the offending databases are detatched. I initially thought that it was a problem with the databases so I took a backup and restored them to a SQL Express instance, all of the data is in tact, and CHECKDB runs without problem. The two databases that were causing a problem last week were not being used; so I took full backups of them and detached the databases, this resolved the problem. However at 0100 GMT this morning to other totally unrelated databases started showing the same problems. There is nothing in the event log to suggest that something happened to the server such as a restart, there are no messages about processes crashing or issues being detected with the storage controller. Speaking to the owner of the company this computer has suffered from "gremlins" in the past, however advice was taken and the motherboard was replaced and the computer rebuilt, memory and processor are the same. Stats: O/S: Windows 2008 Standard Build 6002 CPU: 2x Pentium Dual-Core E5200 @ 2.5GHz RAM: 2GB SQL: 2008 Standard 10.0.2531 Edit: someone posted then deleted a comment about AutoClose, it was turned on on the databases affected. It seems that best practice is to disable it so I have done that with the folllowing. EXECUTE sp_MSforeachdb 'IF (''?'' NOT IN (''master'', ''tempdb'', ''msdb'', ''model'')) EXECUTE (''ALTER DATABASE [?] SET AUTO_CLOSE OFF WITH NO_WAIT'')' I won't know if the problem recurs for some time so I am still open to further answers.

  Read the article

• OCZ Vertex 2 not recognized by Ubuntu installer

  - by Zsub

  As I boot into the Ubuntu 10.10 (or 11.04, doesn't matter) live environment or installer, it just refuses to recognise my Vertex 2. It reports the disk as ATA and not supporting smart, shows no serial number, and doesn't list the size correctly. All fdisk tells me is Unable to read /dev/sda (it's the only storage in the PC). I'm now running a temporary install of Windows 7 off of it, which worked like a charm, so where am I going wrong with Ubuntu... Specs: Asus M4N68T-M LE V2 (BIOS 0702, most recent) OCZ Vertex 2 SSD 60 GB Amd Athlon II X4 640 Patriot PSD34G13332 4GB DDR3 ram (two banks) EDIT I installed a second drive, installed Ubuntu on that and booted, it recognised the SSD just fine. I'm now trying to apt-get upgrade the live-environment. I wonder if there is any way to sort of install Ubuntu from Ubuntu (I boot into the working install on the other drive, install it on the SSD and then boot from the SSD). EDIT2 Ok, so that doesn't work. The install detects the SSD, however, it cannot format it. EDIT3 After a fresh boot I can read out SMART-data and even perform a read-benchmark, but if I try to format it, or do a write-bench, it'll crap out and after that it says SMART is not supported. So basically it seems I can't write to the disk, as it will stop working when I do, I will try to run repeated read-benchmarks to see if that has any effect. EDIT4 I'm running several read benchmarks on the drive right now, they give results that are to be expected from an SSD. If the read-benches don't fail, I can use fdisk on the disk, but it is now stuck trying to re-read the partition table after issueing the 'w' command. EDIT5 Parted Magic did recognize the drive and with hdparm -I even could tell me the drive was in a frozen state. I powercycled it (just pull out the plug from the SSD and plug it back in) and it wasn't frozen anymore. After that I could upgrade the firmware on the drive (still using Parted Magic) and format it to Ext4. After I rebooted into the Ubuntu installer, it wouldn't get recognized and hdparm didn't want to talk to it saying HDIO_DRIVE_CMD(identify) failed: Invalid exchange. EDIT6 For some reason if I enable one of the RAID controllers (the one the SSD is connected to, obviously) Ubuntu will let me format it, mount it and write to it. The installer also recognizes it. However if the raid controller is enabled but no array is defined the motherboard can't boot from it :(

  Read the article

• So I want to separate my Program Files from the hard disk with the other system files. What is the b

  - by grg-n-sox

  So I am running Windows 7 as my only OS. I have two hard drives on my computer. The first one is a 74GB Western Digital 10K RPM Raptor. The second one is a 1TB Seagate Barracuda (couldn't remember if it was a 7200.12 or some other decimal after the 7200). The OS in installed to the Raptor and I am just using the Barracuda for storage. With this setup, in case you couldn't guess already, the Raptor fills up quick and I am constantly having to maintain file locations. And although it is nice to have that quicker boot time and program loading, the time spent maintaining the drive makes me waste more time overall. So I am looking for a way to try to keep it clear while still keeping up system loading speeds. A performance hit on games and such is easily acceptable and as long as I can guarantee a 5GB space on the Raptor, I can always just temporarily move the disc image there. So I am figuring that having games installed like Boarderlands and Mass Effect, as well as having large files such as linux distro DVD disc images in My Documents, I probably should be moving my personal files and Program Files directories to the Barracuda. I currently have folders on the Barracuda for this, but this means routinely copying files over and I can't really do anything with the Program Files folder that already exists. The best I can do is remember to designate the install directory of any program installation to the alternative install directory, which I can't seem to get to ever work right with Steam. With that in mind, is there a way that is not too drastic to let me just change some folders and system settings once and everything works fine afterwards for my setup? I have considered just reinstalling Windows 7 to the Barracuda but that would defeat the purpose of the Raptor except for running disc images off of. I am also heard a bit about being able to use symlinks to fix this, but I have also heard that symlinks in Windows are not necessarily the same and not as well supported on Windows. An example a friend mentioned was something about how if you have a symlink in Windows on a small hard drive to a large hard drive and the contents the symlink points to is larger than the small hard drive's capacity, then Windows will think the smaller hard drive is full. So is there a fix/workaround that will let me use symlinks across hard drives without the issues or is there a better solution I am not being told about, not mentioning, or not thinking of?

  Read the article

• Windows 7 x64 "upgrade" repair fails

  - by Polynomial

  I've been running into issues with Windows Update, which I can't seem to fix. The hotfixes don't work, nor does the Windows update readyness tool, or the manual SP1 upgrade. I get various esoteric errors which nobody seems to have a fix for. Looks like some of the update cache is corrupt and digital signatures seem to be broken on some packages / Windows Update components. Long story short, I have discovered the only option is to do a repair operation on the OS, to repair everything. It's so corrupt that only a complete replacement will fix it. According to various sources (including MSKB) one can perform a repair by running an in-place upgrade. I've got the Windows 7 Ultimate retail disc, which I've inserted into my machine. I ran setup.exe and went through in the following order: Install now Go online to get latest updates (I've also tried not getting updates) Wait for updates to be downloaded Select Windows 7 Ultimate (x64 architecture) and click next Accept the T&Cs, click next Click Upgrade At this point it spends a minute on the "checking compatibility" screen, after which I get the following error: The following issues are preventing Windows from upgrading. Cancel the upgrade, complete each task, and then restart the upgrade to continue. You can’t upgrade 64-bit Windows to a 32-bit version of Windows. To upgrade, obtain a 64-bit version of the installation disc, or go online to see how to install Windows 7 and keep your files and settings. 32-bit Windows cannot be upgraded to a 64-bit version of Windows. To upgrade, obtain a 32-bit version of the Windows installation disc. It also mentions a warning about potential conflicts with a storage driver and VS2010, but that doesn't seem to be the blocking issue. My currently installed version of Windows is Ultimate 64-bit (absolutely sure of this) and the disc is definitely a x86 / x64 combined Ultimate retail disc. There seem to be a few people who have run into this (e.g. this question), but I've not seen any answers. I've checked the event viewer, but can't spot anything in there that's related. Any idea how I can get this working? P.S: Just to pre-empt the inevitable "are you suuuuuuuuuuuuure it's x64 Ultimate?" questions:

  Read the article

• Using Amazon S3 for multiple remote data site uploads, securely

  - by Aitch

  I've been playing about with Amazon S3 a little for the first time and like what I see for various reasons relating to my potential use case. We have multiple (online) remote server boxes harvesting sensor data that is regularly uploaded every hour or so (rsync'ed) to a VPS server. The number of remote server boxes is growing regularly and forecast to keep growing (hundreds). The servers are geographically dispersed. The servers are also automatically built, therefore generic with standard tools and not bespoke per location. The data is many hundreds of files per day. I want to avoid a situation where I need to provision more VPS storage, or additional servers every time we hit the VPS capacity limit, after every N server deployments, whatever N might be. The remote servers can never be considered fully secure due to us not knowing what might happen to them when we are not looking. Our current solution is a bit naive and simply restricts inbound rsync only over ssh to known mac address directories and a known public key. There are plenty of holes to pick in this, I know. Let's say I write or use a script like s3cmd/s3sync to potentially push up the files. Would I need to manage hundreds of access keys and have each server customized to include this (do-able, but key management becomes nightmarish?) Could I restrict inbound connections somehow (eg by mac address), or just allow write-only to any client that was running the script? ( i could deal with a flood of data if someone got into a system? ) having a bucket per remote machine does not seem feasible due to bucket limits? I don't think I want to use a single common key as if one machine is breached then potentially, a malicious hack could get access to the filestore key and start deleting for ll clients, correct? I hope my inexperience has not blinded me to some other solution that might be suggested! I've read lots of examples of people using S3 for backup, but can't really find anything about this sort of data collection, unless my google terminology is wrong... I've written more than I should here, perhaps it can be summarised thus: In a perfect world I just want to have one of our techs install a new remote server into a location and it automagically starts sending files home with little or no intervention, and minimises risk? Pipedream or feasible? TIA, Aitch

  Read the article

• Can someone explain RAID-0 in plain English?

  - by Edward Tanguay

  I've heard about and read about RAID throughout the years and understand it theoretically as a way to help e.g. server PCs reduce the chance of data loss, but now I am buying a new PC which I want to be as fast as possible and have learned that having two drives can considerably increase the perceived performance of your machine. In the question Recommendations for hard drive performance boost, the author says he is going to RAID-0 two 7200 RPM drives together. What does this mean in practical terms for me with Windows 7 installed, e.g. can I buy two drives, go into the device manager and "raid-0 them together"? I am not a network administrator or a hardware guy, I'm just a developer who is going to have a computer store build me a super fast machine next week. I can read the wikipedia page on RAID but it is just way too many trees and not enough forest to help me build a faster PC: RAID-0: "Striped set without parity" or "Striping". Provides improved performance and additional storage but no redundancy or fault tolerance. Because there is no redundancy, this level is not actually a Redundant Array of Inexpensive Disks, i.e. not true RAID. However, because of the similarities to RAID (especially the need for a controller to distribute data across multiple disks), simple strip sets are normally referred to as RAID 0. Any disk failure destroys the array, which has greater consequences with more disks in the array (at a minimum, catastrophic data loss is twice as severe compared to single drives without RAID). A single disk failure destroys the entire array because when data is written to a RAID 0 drive, the data is broken into fragments. The number of fragments is dictated by the number of disks in the array. The fragments are written to their respective disks simultaneously on the same sector. This allows smaller sections of the entire chunk of data to be read off the drive in parallel, increasing bandwidth. RAID 0 does not implement error checking so any error is unrecoverable. More disks in the array means higher bandwidth, but greater risk of data loss. So in plain English, how can "RAID-0" help me build a faster Windows-7 PC that I am going to order next week?

  Read the article

• The Koyal Group Info Mag News¦Charged building material could make the renewable grid a reality

  - by Chyler Tilton

  What if your cell phone didn’t come with a battery? Imagine, instead, if the material from which your phone was built was a battery. The promise of strong load-bearing materials that can also work as batteries represents something of a holy grail for engineers. And in a letter published online in Nano Letters last week, a team of researchers from Vanderbilt University describes what it says is a breakthrough in turning that dream into an electrocharged reality. The researchers etched nanopores into silicon layers, which were infused with a polyethylene oxide-ionic liquid composite and coated with an atomically thin layer of carbon. In doing so, they created small but strong supercapacitor battery systems, which stored electricity in a solid electrolyte, instead of using corrosive chemical liquids found in traditional batteries. These supercapacitors could store and release about 98 percent of the energy that was used to charge them, and they held onto their charges even as they were squashed and stretched at pressures up to 44 pounds per square inch. Small pieces of them were even strong enough to hang a laptop from—a big, fat Dell, no less. Although the supercapacitors resemble small charcoal wafers, they could theoretically be molded into just about any shape, including a cell phone’s casing or the chassis of a sedan. They could also be charged—and evacuated of their charge—in less time than is the case for traditional batteries. “We’ve demonstrated, for the first time, the simple proof-of-concept that this can be done,” says Cary Pint, an assistant professor in the university’s mechanical engineering department and one of the authors of the new paper. “Now we can extend this to all kinds of different materials systems to make practical composites with materials specifically tailored to a host of different types of applications. We see this as being just the tip of a very massive iceberg.” Pint says potential applications for such materials would go well beyond “neat tech gadgets,” eventually becoming a “transformational technology” in everything from rocket ships to sedans to home building materials. “These types of systems could range in size from electric powered aircraft all the way down to little tiny flying robots, where adding an extra on-board battery inhibits the potential capability of the system,” Pint says. And they could help the world shift to the intermittencies of renewable energy power grids, where powerful batteries are needed to help keep the lights on when the sun is down or when the wind is not blowing. “Using the materials that make up a home as the native platform for energy storage to complement intermittent resources could also open the door to improve the prospects for solar energy on the U.S. grid,” Pint says. “I personally believe that these types of multifunctional materials are critical to a sustainable electric grid system that integrates solar energy as a key power source.”

  Read the article

< Previous Page | 245 246 247 248 249 250 251 252 253 254 255 256  | Next Page >