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• Fast serialization/deserialization of structs

  - by user256890

  I have huge amont of geographic data represented in simple object structure consisting only structs. All of my fields are of value type. public struct Child { readonly float X; readonly float Y; readonly int myField; } public struct Parent { readonly int id; readonly int field1; readonly int field2; readonly Child[] children; } The data is chunked up nicely to small portions of Parent[]-s. Each array contains a few thousands Parent instances. I have way too much data to keep all in memory, so I need to swap these chunks to disk back and forth. (One file would result approx. 2-300KB). What would be the most efficient way of serializing/deserializing the Parent[] to a byte[] for dumpint to disk and reading back? Concerning speed, I am particularly interested in fast deserialization, write speed is not that critical. Would simple BinarySerializer good enough? Or should I hack around with StructLayout (see accepted answer)? I am not sure if that would work with array field of Parent.children. UPDATE: Response to comments - Yes, the objects are immutable (code updated) and indeed the children field is not value type. 300KB sounds not much but I have zillions of files like that, so speed does matter.

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• Mercurial: Class library that will exist for both .NET 3.5 and 4.0?

  - by Lasse V. Karlsen

  I have a rather big class library written in .NET 3.5 that I'd like to upgrade to make available for .NET 4.0 as well. In that process, I will rip out a lot of old junk, and rewrite some code to better take advantage of the new classes and support in .NET 4.0 (like TPL.) The class libraries will thus diverge, but still be similar enough that some bug-fixes can be done to both in the same manner. How should I best organize this class library in Mercurial? I'm using Kiln (fogbugz) if that matters. I'm thinking: Named branches in one repository, can then transplant any bugfixes from one to the other Unnamed branches in one repository, can also transplant, but I think this will look messy Separate repositories, will have to reimplement the bugfixes (or use a non-mercurial-integraded compare tool to help me) What would you do? (any other alternatives that I haven't though of is welcome as well.) Note that the class libraries will diverge pretty heavily in areas, I have some remnants of old collection-type code that does something similar to Linq that I will remove, and some code that uses it that I will rewrite to use the Linq-methods instead. As such, just copying the project files and using #if NET40..#endif sections is not going to work out. Also, the 3.5 version of the class library will not be getting many new features, mostly just critical bug-fixes, so keeping both versions equally "alive" isn't really necessary. Thus, separate copies of all the files are good enough.

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• Firefox "intelligently" and silently fixes incorrect file references in CSS and Scripts at runtime.

  - by bobsoap

  Well this is a really weird issue, I really didn't find anything on this elsewhere so I thought I'd address it here. Say I have an "image.jpg" and accidentally reference it in the CSS like so: url(imag.jpg) Note the missing "e". Now for me, Firefox is so incredibly clever that it will still find the correct image, but NOT SPIT OUT A WARNING. So I assume that everything is ok. But later, when I test the page in any other browser, all of a sudden the image doesn't display (and rightly so). That's because Firefox thought it was a good idea to correct my error without telling me. This becomes more critical with scripts. Firefox will also auto-correct a typo in a reference. I just wasted a whole hour scratching my head and trying to debug an ajax function in Webkit - turns out, I just had a typo where I included the file. Why on earth does Firefox do this without telling, and where the heck can I turn this off? This has first occured somewhere around FF 3.0 and still persists in 3.6.3. /rant an thank fo any inpu ;)

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• Python Webkit browser's inspector is missing a few things

  - by NoBugs

  I'm using a Webkit browser inspector like this. When I run it in Ubuntu 12.10, I'm getting errors when using the inspector. For example: ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Go to line" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Filter" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Search Previous" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Search Next" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "a:" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "%d of %d" not found. (geany:2487): Gdk-CRITICAL **: IA__gdk_error_trap_pop: assertion `gdk_error_traps != NULL' failed ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Sources Panel" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Toggle breakpoint" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Painting" not found. I also noticed the breadcrumb/slider bar doesn't show when you have the console in the lower half: I don't remember this in earlier versions, and when I use the GTK3 version (from gi.repository import WebKit etc) it has similar problem, and is even worse, scrollbars don't have arrows at top and bottom. Am I missing a step on initializing the Webkit inspector or English locale for it? I would like to debug this issue, but since the inspector object isn't a webview object, I'm not sure I can add an inspector to the inspector? (like how you can use F12 when inspector is its own window in Chrome/Chromium, which lets you debug that inspector). It should be possible, but maybe not with pyGTK?

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• Batch Inserts And Prepared Query Error

  - by ircmaxell

  Ok, so I need to populate a MS Access database table with results from a MySQL query. That's not hard at all. I've got the program written to where it copies a template .mdb file to a temp name and opens it via odbc. No problem so far. I've noticed that Access does not support batch inserting (VALUES (foo, bar), (second, query), (third query)). So that means I need to execute one query per row (there are potentially hundreds of thousands of rows). Initial performance tests show a rate of around 900 inserts/sec into Access. With our largest data sets, that could mean execution times of minutes (Which isn't the end of the world, but obviously the faster the better). So, I tried testing a prepared statement. But I keep getting an error (Warning: odbc_execute() [function.odbc-execute]: SQL error: [Microsoft][ODBC Microsoft Access Driver]COUNT field incorrect , SQL state 07001 in SQLExecute in D:\....php on line 30). Here's the code I'm using (Line 30 is odbc_execute): $sql = 'INSERT INTO table ([field0], [field1], [field2], [field3], [field4], [field5]) VALUES (?, ?, ?, ?, ?, ?)'; $stmt = odbc_prepare($conn, $sql); for ($i = 200001; $i < 300001; $i++) { $a = array($i, "Field1 $", "Field2 $i", "Field3 $i", "Field4 $i", $i); odbc_execute($stmt, $a); } So my question is two fold. First, is there any idea on why I'm getting that error (I've checked, and the number in the array matches the field list which matches the number of parameter ? markers)? And second, should I even bother with this or just use the straight INSERT statements? Like I said, time isn't critical, but if it's possible, I'd like to get that time as low as possible (Then again, I may be limited by disk throughput, since 900 operations/sec is high already)... Thanks

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• Limiting object allocation over multiple threads

  - by John

  I have an application which retrieves and caches the results of a clients query. The client then requests different chunks of data and the application sends the relevant results and removes them from the cache. A new requirement for this application is that there needs to be a run-time configurable maximum number of results which may be cached. I've taken the naive approach and implemented this by using a counter under a lock which is incremented every time a result is cached and decremented whenever a result is removed from the cache. Unfortunately, this has drastically reduced the applications performance when processing a large number of concurrent requests. I have tried both a critical section lock and spin-lock; the performance improves a bit with a spin-lock, but is still unacceptably slow. Is there a better way to solve this problem which may improve performance? Right now I have a thread pool that services requests and each request is tied to a Request object which stores that cached results for that particular request. Here is a simplified pseudo code version of my current implementation: void ResultCallback( Result result, Request *request ) { lock totalResultsCached lock cachedLimit if( totalResultsCached + 1 > cachedLimit ) { unlock cachedLimit unlock totalResultsCached //cancel the request return; } ++totalResultsCached; unlock cachedLimit unlock totalResultsCached request.add(result) } void SendResults( int resultsToSend, Request *request ) { while ( resultsToSend > 0 ) { send(request.remove()) lock totalResultsCached --totalResultsCached unlock totalResultsCached --resultsToSend; } }

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• Overhead of calling tiny functions from a tight inner loop? [C++]

  - by John

  Say you see a loop like this one: for(int i=0; i<thing.getParent().getObjectModel().getElements(SOME_TYPE).count(); ++i) { thing.getData().insert( thing.GetData().Count(), thing.getParent().getObjectModel().getElements(SOME_TYPE)[i].getName() ); } if this was Java I'd probably not think twice. But in performance-critical sections of C++, it makes me want to tinker with it... however I don't know if the compiler is smart enough to make it futile. This is a made up example but all it's doing is inserting strings into a container. Please don't assume any of these are STL types, think in general terms about the following: Is having a messy condition in the for loop going to get evaluated each time, or only once? If those get methods are simply returning references to member variables on the objects, will they be inlined away? Would you expect custom [] operators to get optimized at all? In other words is it worth the time (in performance only, not readability) to convert it to something like: ElementContainer &source = thing.getParent().getObjectModel().getElements(SOME_TYPE); int num = source.count(); Store &destination = thing.getData(); for(int i=0;i<num;++i) { destination.insert(thing.GetData().Count(), source[i].getName(); } Remember, this is a tight loop, called millions of times a second. What I wonder is if all this will shave a couple of cycles per loop or something more substantial? Yes I know the quote about "premature optimisation". And I know that profiling is important. But this is a more general question about modern compilers, Visual Studio in particular.

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• Question about how AppFabric's cache feature can be used.

  - by Kevin Buchan

  Question about how AppFabric's cache feature can be used. I apologize for asking a question that I should be able to answer from the documentation, but I have read and read and searched and cannot answer this question, which leads me to believe that I have a fundamentally flawed understanding of what AppFabric's caching capabilities are intended for. I work for a geographically disperse company. We have a particular application that was originally written as a client/server application. It’s so massive and business critical that we want to baby step converting it to a better architected solution. One of the ideas we had was to convert the app to read its data using WCF calls to a co-located web server that would cache communication with the database in the United States. The nature of the application is such that everyone will tend to be viewing the same 2000 records or so with only occasional updates and those updates will be made by a limited set of users. I was hoping that AppFabric’s cache mechanism would allow me to set up one global cache and when a user in Asia, for example, requested data that was not in the cache or was stale that the web server would read from the database in the USA, provide the data to the user, then update the cache which would propagate that data to the other web servers so that they would know not to go back to the database themselves. Can AppFabric work this way or should I just have the servers retrieve their own data from the database?

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• How important is it that models be consistent across project components?

  - by RonLugge

  I have a project with two components, a server-side component and a client-side component. For various reasons, the client-side device doesn't carry a fully copy of the database around. How important is it that my models have a 1:1 correlation between the two sides? And, to extend the question to my bigger concern, are there any time-bombs I'm going to run into down the line if they don't? I'm not talking about having different information on each side, but rather the way the information is encapsulated will vary. (Obviously, storage mechanisms will also vary) The server side will store each user, each review, each 'item' with seperate tables, and create links between them to gather data as necessary. The client side shouldn't have a complete user database, however, so rather than link against the user for gathering things like 'name', I'd store that on the review. In other words... --- Server Side --- Item: +id //Store stuff about the item User: +id +Name -Password Review: +id +itemId +rating +text +userId --- Device Side --- Item: +id +AverageRating Review: +id +rating +text +userId +name User: +id +Name //Stuff The basic idea is that certain 'critical' information gets moved one level 'up'. A user gets the list of 'items' relevant to their query, with certain review-orientation moved up (i. e. average rating). If they want more info, they query the detail view for the item, and the actual reviews get queried and added to the dataset (and displayed). If they query the actual review, the review gets queried and they pick up some additional user info along the way (maybe; I'm not sure if the user would have any use for any of the additional user information). My basic concern is that I don't wan't to glut the user's bandwidth or local storage with a huge variety of information that they just don't need, even if proper database normalizations suggests that information REALLY should be stored at a 'lower' level. I've phrased this as a fairly low-level conceptual issue because that's the level I'm trying to think / worry over, but if it matters I'm creating a PHP / MySQL server that provides data for a iOS / CoreData client.

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• saving mySql row checkpoint in table ?

  - by Keet

  hello, I am having a wee problem, and I am sure there is a more convenient/simpler way to achieve the solution, but all searches are throw in up a blanks at the moment ! I have a mysql db that is regularly updated by php page [ via a cron job ] this adds or deletes entries as appropriate. My issue is that I also need to check if any details [ie the phone number or similar] for the entry have changed, but doing this at every call is not possible [ not only does is seem to me to be overkill, but I am restricted by a 3rd party api call limit] Plus this is not critical info. So I was thinking it might be best to just check one entry per page call, and iterate through the rows/entires with each successive page call. What would be the best way of doing this, ie keeping track of which entry/row in the table that the should be checked next? I have 2 ideas of how to implement this: 1 ) The id of current row could be save to a file on the server [ surely not the best way] 2) an extra boolean field [check] is add to the table, set to True on the first entry and false to all other. Then on each page call it; finds 'where check = TRUE' runs the update check on this row, 'set check = FALSE' 'set [the next row] check = TRUE' Si this the best way to do this, or does anyone have any better sugestion ? thanks in advance ! .k PS sorry about the title

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• Optimal (Time paradigm) solution to check variable within boundary

  - by kumar_m_kiran

  Hi All, Sorry if the question is very naive. I will have to check the below condition in my code 0 < x < y i.e code similar to if(x > 0 && x < y) The basic problem at system level is - currently, for every call (Telecom domain terminology), my existing code is hit (many times). So performance is very very critical, Now, I need to add a check for boundary checking (at many location - but different boundary comparison at each location). At very normal level of coding, the above comparison would look very naive without any issue. However, when added over my statistics module (which is dipped many times), performance will go down. So I would like to know the best possible way to handle the above scenario (kind of optimal way for limits checking technique). Like for example, if bit comparison works better than normal comparison or can both the comparison be evaluation in shorter time span? Other Info x is unsigned integer (which must be checked to be greater than 0 and less than y). y is unsigned integer. y is a non-const and varies for every comparison. Here time is the constraint compared to space. Language - C++. Now, later if I need to change the attribute of y to a float/double, would there be another way to optimize the check (i.e will the suggested optimal technique for integer become non-optimal solution when y is changed to float/double). Thanks in advance for any input. PS : OS used is SUSE 10 64 bit x64_64, AIX 5.3 64 bit, HP UX 11.1 A 64.

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• Value types of variable size

  - by YellPika

  I'm trying to code a small math library in C#. I wanted to create a generic vector structure where the user could define the element type (int, long, float, double, etc.) and dimensions. My first attempt was something like this... public struct Vector<T> { public readonly int Dimensions; public readonly T[] Elements; // etc... } Unfortunately, Elements, being an array, is also a reference type. Thus, doing this, Vector<int> a = ...; Vector<int> b = a; a[0] = 1; b[0] = 2; would result in both a[0] and b[0] equaling 2. My second attempt was to define an interface IVector<T>, and then use Reflection.Emit to automatically generate the appropriate type at runtime. The resulting classes would look roughly like this: public struct Int32Vector3 : IVector<T> { public int Element0; public int Element1; public int Element2; public int Dimensions { get { return 3; } } // etc... } This seemed fine until I found out that interfaces seem to act like references to the underlying object. If I passed an IVector to a function, and changes to the elements in the function would be reflected in the original vector. What I think is my problem here is that I need to be able to create classes that have a user specified number of fields. I can't use arrays, and I can't use inheritance. Does anyone have a solution? EDIT: This library is going to be used in performance critical situations, so reference types are not an option.

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• fgets throwing unhandled exception while parsing stl

  - by user3478400

  I am new to c++, I am trying to parse a stl file which is of about 64MB and has about ~18K lines in it. The code works fine for first few 100 lines but then fgets throws following exception: "Unhandled exception at 0x77B0BAC5 (ntdll.dll) in STLparser.exe: 0xC0000024: There is a mismatch between the type of object required by the requested operation and the type of object that is specified in the request." I have checked manually the line for which fgets throws exception, there is nothing out of ordinary there. I am out of options for now. Any help to fix this issue will be greatly appreciated. ================CODE========================== #include<fstream> #include<iostream> #include"ParseString.h" #include"Vectors.h" using namespace std; int main(void) { //Define variables FILE *file; char *line = new char; parsestring oneline; int n_Vols = 0, n_Elms = 0, n_nods = -1, E = 0; Nod *nodes = new Nod(); Nod dummy; Elm *elements = new Elm(); int mycounter = 0; //Open file fopen_s(&file, "sample.stl", "r"); while (fgets(line, 1024, file) != NULL) //**********Getting Error Here************* { // populate required data } fclose(file); printf("%d,%d,%d", n_Vols, n_Elms, n_nods); getchar(); return 0; } ===================When broken, execution resumes at this function (not my function, something internal) void __cdecl _unlock ( int locknum ) { /* * leave the critical section. */ LeaveCriticalSection( _locktable[locknum].lock ); }

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• backup and restoration of a freeipa infrastructure

  - by Sirex

  I'm finding the documentation on ipa server backup and restoration sadly lacking, and being so centrally critical it's not something i'm really happy about shooting in the dark with - could some kind soul more knowledable in the matter please attempt to provide an idiot-proof guide to backing up and restoring of IPA server(s) ? Particularly the main server (the cert signing one). ...We're looking towards rolling out ipa in a two server setup (1 master, 1 replica). I'm using dns srv records to handle failover, hence a loss of the replica isn't a big deal as i could make a new one and force a resync to happen - it's losing the master that bothered me. The thing that i'm really struggling with is locating a step-by-step procedure for backing up and restoring the master server. I'm aware that whole-VM snapshot is the recommended way of doing IPA server backup, but that isn't an option at this time for us. I'm also aware that freeipa 3.2.0 includes some sort of backup command build in, but that isn't in the ipa version of centos, and i don't expect it will be for some time yet. I've been trying many different methods, but none of them seem to restore cleanly, amongst others, i've tried; a command similar to db2ldif.pl -D "cn=directory manager" -w - -n userroot -a /root/userroot.ldif the script from here to produce three ldif files -- one for the domain ({domain}-userroot), and two for the ipa server (ipa-ipaca and ipa-userroot): Most of the restores i've tried have been similar to the form of: ldif2db.pl -D "cn=directory manager" -w - -n userroot -i userroot.ldif which seems to work and reports no errors, but totally borks the ipa install on the machine and i can no longer login with either the admin password on the backed up server, or the one i set it to on installation before attempting the ldif2db command (i'm installing ipa-server and running ipa-server-install, then attempting the restore). I'm not overly bothered about losing the CA, having to rejoin the domain, losing replication etc etc (although it'd be awesome if that could be avoided) but in the instance of the main server dropping i'd really like to avoid having to re-enter all the user/group information. I guess in the instance of losing the main server i could promote the other one and replicate in the other direction, but i've not tried that, either. Has anyone done that ? tl;dr: Can someone provide an idiots guide to backing up and restoring an IPA server (preferably on CentOS 6) in a clear enough way that'd make me feel confident it'll actually work when the dreaded time comes ? Crayons are optional, but appreciated ;-) I can't be the only person struggling with this, seeing how widely used IPA is, surely ?

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• Linux Mint 14 severe overheating

  - by agvares

  I've tried switching to Mint (it was Mint 12) about 6 months ago, but failed to do it due to enormous overheating which made it virtually impossible to run any applications more complex than Gedit. Time had passed, and now I'm back again with Mint 14, but feeling way more determined. What I face are the following issues: 1) Great overheating (and by great I mean that just by doing nothing my CPU temp is floating around 70-75 C, which I find a lot) 2) Running multiple applications (let's say Chrome, Skype and Pidgin) results in critical overheating and immediate shutdown of the system 3) Due to the stuff listed above, my battery drains in about 10-15 minutes, pretty much turning my laptop into a crippled desktop machine I've got a HP-dv6 laptop (i7, 6gb RAM, dual graphics) Here's the output of lspci: 00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09) 00:01.0 PCI bridge: Intel Corporation Xeon E3-1200/2nd Generation Core Processor Family PCI Express Root Port (rev 09) 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) 00:16.0 Communication controller: Intel Corporation 6 Series/C200 Series Chipset Family MEI Controller #1 (rev 04) 00:1a.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #2 (rev 05) 00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 05) 00:1c.0 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 1 (rev b5) 00:1c.1 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 2 (rev b5) 00:1c.2 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 3 (rev b5) 00:1c.3 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 4 (rev b5) 00:1d.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1 (rev 05) 00:1f.0 ISA bridge: Intel Corporation HM65 Express Chipset Family LPC Controller (rev 05) 00:1f.2 SATA controller: Intel Corporation 6 Series/C200 Series Chipset Family 6 port SATA AHCI Controller (rev 05) 00:1f.3 SMBus: Intel Corporation 6 Series/C200 Series Chipset Family SMBus Controller (rev 05) 01:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Whistler XT [AMD Radeon HD 6700M Series] 07:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 06) 0d:00.0 Network controller: Broadcom Corporation BCM4313 802.11b/g/n Wireless LAN Controller (rev 01) 13:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5209 PCI Express Card Reader (rev 01) 19:00.0 USB controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 04) what i've tried to do already: 1) I've edited my grub file to add some "splash" arguments there 2) Installed jupiter and powertop 3) Tried to upgrade to newer kernels (up to 3.8), btw running anything newer than 3.5 results in both resolution and wi-fi detection fail 4) Read lots of forum threads devoted to the topic So, my question is simple: What else might I do to become finally able to use Mint as my default OS without the risk of being burned alive by the CPU heat?

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• Gateway GT5220 Boot/POST Failure

  - by John Rudy

  I have a Gateway GT5220 I'm troubleshooting. It is, in fact, the machine I just gave my father for his birthday a couple months ago. (Prior to that, it was my home PC. My home PC is now the MacBook on which I'm writing this.) Before going any further, I suspect that the answer will be, "It's worse than that, it's dead, Jim, it's dead, Jim, it's dead, Jim." At least, mobo and/or CPU. The initial symptoms were as follows: Turn on power All fans fire up (thus making it so I can't hear if the hard drive is spinning or not, nor are my hands sensitive enough anymore to feel it) No LEDs remained lit on the front panel. (Initially, the hard drive indicator flashed briefly.) No beep, no video, no nothing. Following some advice I found here, I tried to "drain the stored power." After following those steps, the new symptoms were: Turn on power All fans fire up The front panel LEDs remained lit! After about 20, maybe 30 seconds, we had video! Sort of. We got to the Gateway splash/POST screen, which appeared thoroughly corrupted. How corrupted? Well, I imagine it's what a POST screen would look like after reading the wrong passage out of the Necronomicon: It stayed there. I gave it at least 5, maybe 6 minutes, and it didn't move. So I shut her down, started her up again, and now (this is where we currently stand, symptomatically) we have this: Turn on power All fans fire up The front panel LEDs remain lit No video, no beep, no nothing. I'm a software guy; haven't done real hardware troubleshooting in years. My gut tells me that the mobo and/or CPU is fried, and unfortunately my gut didn't get to be as big as it is being wrong all the time. :( In addition to the link above, I have read all of the following (trying to save you some LMGTFY trouble): Gateway Support POST Error Messages and Handling About a zillion (useless) POST beep code sites A kioskea.net post indicating that most likely we're at what I consider "total loss" (mobo and/or CPU) My questions: Are there any conditions other than mobo/CPU that could cause symptoms like these? Is it worth my time to try the next hardware troubleshooting step?(IE, remove all non-critical hardware from the machine, try to boot, systematically replace one by one until we find the failing component) Which mobos will fit in the Gateway GT5220 case (with rear ports correctly aligned)? (Why this is not a dupe: I wouldn't have posted this question if it hadn't been for the funkadelic possessed video display on the one occasion we got video out. I think that justified this not being an exact dupe. Of course, if the community overrules, I will understand.)

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• What "pieces" are needed in order to set up a cluster of physical servers?

  - by Chris Dutrow

  Background: Currently, we use Rackspace cloud servers. We have no intention to stop using them, but would like to look into setting up a cluster of physical servers (probably desktop computers in the $400 range with 8gb memory each) to offset some of our load and work as a secondary, more powerful, less reliable system. To put things in perspective, we can buy comparable desktop computers for the same price as we pay in one month to rent them on Rackspace Cloud. I understand that this is generally a dumb idea. However, in this particular instance, the server cluster is needed for its computation power. It is not mission-critical, it does not host a consumer-facing website, and if it goes down for a day or two, its not really a problem. Currently, we have access to business class verizon fios. If I understand correctly, we can get at least 25 dedicated IP addresses with this service, this should be enough. Requirements: Each server runs Linux Centos 6.3 Some of the servers run Python and execute processes from a task queue (Redis or RabbitMQ) Some of the servers are capable of serving static files and Python driven REST APIs Some of the servers host a Cassandra database cluster One or more of the servers are a Redis database servers One or more of the servers are PostgreSQL servers Questions: What kind of router or switch is needed? We would like the computers to be able to communicate effectively with each other via internal IP addresses. This is especially important for communicating with servers hosting Redis that need to be able to respond to requests very quickly. Are there special switches or routers that need to be used to connect the servers together? Are Desktop computers ok for this? We have found that we are mostly RAM-bottle necked, I understand that some servers have highly superior CPUs, but I'm not sure we need CPU power as much as we need RAM, which is cheap in Desktop computers. Will we have problems with the WIFI cards in the desktops or any other unexpected hardware limitation? What tools should be used to "image" the servers. For example, when we get an installation right for a Redis server or Cassandra node, are there tools that come with Linux Centos 6.3 to image the server to a USB drive or something like that? Or do we need to use some other software for this? What other things are we missing that we should be concerned about? Thanks so much!

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• 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.”

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• Safer RAID5 rebuilds using partially failed disks?

  - by arcticmac

  There have been lots of articles posted recently about how RAID5 is dangerous because of long resilver times, and in particular because of increasing chances of encountering a URE during the resilver. Obviously this is a significant concern. However, it seems that in many cases of interest (as long as you're keeping some kind of eye on your disks), when it comes time to rebuild the array, the disk that I'm replacing is still mostly readable. If you try to explain this predicament to the average layperson, they are typically very confused as to why you have two almost completely functional disks but can't produce one working array. It seems to me that there ought to be some way to take advantage of this to make rebuilds safer, as long as I'm willing to have the RAID5 be read-only for a couple of days while it rebuilds. Conceptually, what I have in mind looks something like this: When a disk fails, immediately take the RAID5 offline or mount it read-only Attach a new disk (either in a spare bay, or externally via eSATA) and begin rebuilding it to replace the failed one. If known, perhaps start with the stripes in which the failure occurred, to minimize the chances of losing those if another disk fails. In the event that a second disk experiences a URE or other failure during the rebuild, try to source that data from the disk that is being replaced. Presumably if this happens, more rebuilding would be necessary. When complete, shut down the server, swap the replacement drive into the original bay if desired, and bring the array back up. Obviously such a process would not be appropriate for applications where uptime is critical or data loss cannot be tolerated, but it seems to me that this could help considerably to improve the reliability of RAID5. I assume that there's not a good way to implement a recovery like this at present, given that I haven't seen any indication of tools that are designed to do this, and that it seems like it would be rather obtuse to work out manually. Are there also technical issues with it that I haven't thought of (I'm still fairly new to RAID stuff)? Any thoughts on how hard something like this would be to implement (e.g. in linux md raid)?

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• Intermittent Disconnection of Client Computers from Domain Server

  - by dilip nagle

  The Background: I have Windows 2008 server Enterprise Version with 25 user cal licences. It has a domain and all users and a network shared HP printer in it. The Server has two network cards and both these cards as well as all client machines are on IP addressing scheme of 192.168.1.* with subnetmask 255.255.255.0. Of the two network cards viz. 192.168.1.231 and 192.168.1.233, only 192.168.1.231 is registered with DNS. In 192.168.1.233(i.e. 2nd network card) has default getway as 192.168.1.231 and dns address as 192.168.1.231. The Server has three hard disks with capacities as 500gb, 500gb and 1TB and are partitioned as (C,D,E), (F,G) and (K) with partition K having all user data into various Shared Folders. Each of these folders(On Partition K), are mapped onto each user's computer as per the right of access given to them. The Problem: The Server was installed about 6 months ago and till date not even once, the Server has Hung or has given any problem. All the Clients computers are able to run the web based software from their computers via ip address, e.g. http://192.168.1.231/webERP/default.aspx. However, occassionally, when any client computer tries to browse network mappings, it hangs. Again, there is no fixed pattern. This may happen after running smoothly for say 3 days. On each Client's machine, the network settings are as follows: IP Address: 192.168.1.* where * is 1,2,3 .... Sunnetmask: 255.255.255.0 defauly getway: 192.168.1.231 Which is a server card and DNS address. preferred DNS Server: 192.168.1.231 In Advanced Tab under Wins: LMHostLookup is Unticked and default is radio buttoned. Ideally, I would have loved to have Disabled NETBIOS over TCP/IP but some network printers do not get accessed if this option is enabled(ie. Radio Buttoned). Bacause Disabling Netbios will drastically reduce traffic of NETBIOS broadcasting to all the computers on the net to do naming resolution. On Server, I have WINs Running which I have Scavanged Records, verified Database Integrity etc, removed Tombstoned Records etc. The Critical Errors shown only once a day when the server is statred are 4224(WINS) and 12923 - Server Licencing failed to Update DNS Record. I fail to understand as why do client machines HANG when they try to browse mapped network shared folders on K Drive. Kindly Advice

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• Do RAID controllers commonly have SATA drive brand compatibility issues?

  - by Jeff Atwood

  We've struggled with the RAID controller in our database server, a Lenovo ThinkServer RD120. It is a rebranded Adaptec that Lenovo / IBM dubs the ServeRAID 8k. We have patched this ServeRAID 8k up to the very latest and greatest: RAID bios version RAID backplane bios version Windows Server 2008 driver This RAID controller has had multiple critical BIOS updates even in the short 4 month time we've owned it, and the change history is just.. well, scary. We've tried both write-back and write-through strategies on the logical RAID drives. We still get intermittent I/O errors under heavy disk activity. They are not common, but serious when they happen, as they cause SQL Server 2008 I/O timeouts and sometimes failure of SQL connection pools. We were at the end of our rope troubleshooting this problem. Short of hardcore stuff like replacing the entire server, or replacing the RAID hardware, we were getting desperate. When I first got the server, I had a problem where drive bay #6 wasn't recognized. Switching out hard drives to a different brand, strangely, fixed this -- and updating the RAID BIOS (for the first of many times) fixed it permanently, so I was able to use the original "incompatible" drive in bay 6. On a hunch, I began to assume that the Western Digital SATA hard drives I chose were somehow incompatible with the ServeRAID 8k controller. Buying 6 new hard drives was one of the cheaper options on the table, so I went for 6 Hitachi (aka IBM, aka Lenovo) hard drives under the theory that an IBM/Lenovo RAID controller is more likely to work with the drives it's typically sold with. Looks like that hunch paid off -- we've been through three of our heaviest load days (mon,tue,wed) without a single I/O error of any kind. Prior to this we regularly had at least one I/O "event" in this time frame. It sure looks like switching brands of hard drive has fixed our intermittent RAID I/O problems! While I understand that IBM/Lenovo probably tests their RAID controller exclusively with their own brand of hard drives, I'm disturbed that a RAID controller would have such subtle I/O problems with particular brands of hard drives. So my question is, is this sort of SATA drive incompatibility common with RAID controllers? Are there some brands of drives that work better than others, or are "validated" against particular RAID controller? I had sort of assumed that all commodity SATA hard drives were alike and would work reasonably well in any given RAID controller (of sufficient quality).

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• HP UX can not boot from Ignite Tape

  - by Spirit

  We have hp rp2470 server running hp-ux 11.00, with LVM mirroring. As for redundancy we have second rp2470 same hw (same two processors, same ram, same two hdd’s, same number of lan cards). I want to clone first one to the second. For that purpose I am making ignite tape with the following command: make_tape_recovery -x inc_entire=vg00 Ignite tape finishes without problems. When I boot second server from this ignate tape, server is starting to boot, and ignite restore finishes without any errors, only few notes, which are normal. However vmunix is not booting and when restore finishes, it boot to ISL prompt. From this I cannot boot /stand/vmunix. I tried to run recovery shell but no success. When recovery shell ask to do frecover to restore critical files, then I receive error: frecover(5405): unable to open /dev/rmt/0m At first I thought that the problem might be in the difference of the firmware version of the servers: fw version of production server is: Firmware Version 43.50 and fw version of backup server is: Firmware Version 42.19 So i did a fw upgrade of my backup server so that both servers are v43.50, and tried a recovery but again cant boot the system. Next I did another archive tape with -I (Interactive) flag: make_tape_recovery -I -x inc_entire=vg00 and tried recovery with it, again no good. I cannot find any error or warnings on ignite log, and I cannot boot hpux. I am only on ISL prompt. This is what i've noticed on the gsp logs: ************* SYSTEM ALERT ************** SYSTEM NAME: mcnfwim1 DATE: 07/27/2003 TIME: 10:18:49 ALERT LEVEL: 6 = Boot possible, pending failure - action required REASON FOR ALERT SOURCE: 8 = I/O SOURCE DETAIL: 6 = disk SOURCE ID: 0 PROBLEM DETAIL: 0 = no problem detail LEDs: RUN ATTENTION FAULT REMOTE POWER FLASH OFF ON ON ON LED State: Boot Failed. Running non-OS code. Check Chassis and Console Logs for error messages. 0x00000060860010B0 00000000 00000000 - type 0 = Data Field Unused 0x58000860860010B0 00006706 1B0A1231 - type 11 = Timestamp 07/27/2003 10:18:49 And another gsp log: Log Entry # 3 : SYSTEM NAME: mcnfwim1 DATE: 07/27/2003 TIME: 10:12:20 ALERT LEVEL: 6 = Boot possible, pending failure - action required SOURCE: 8 = I/O SOURCE DETAIL: 6 = disk SOURCE ID: 0 PROBLEM DETAIL: 0 = no problem detail CALLER ACTIVITY: 1 = test STATUS: 0 CALLER SUBACTIVITY: 0B = implementation dependent REPORTING ENTITY TYPE: 0 = system firmware REPORTING ENTITY ID: 00 0x00000060860010B0 00000000 00000000 type 0 = Data Field Unused 0x58000860860010B0 00006706 1B0A0C14 type 11 = Timestamp 07/27/2003 10:12:20 Type CR for next entry, - CR for previous entry, Q CR to quit. Please note that I can not change anything on the production server. I can only make changes to the backup server. Any help is appreciated.

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• Real-time offline folder-to-folder backup application needed (Windows)

  - by niktech

  I recently started using Intel Matrix Storage RAID solution that allowed me to use my 5 1TB drives for two RAID volumes. First one a 1TB RAID 0 striped across all 5 drives and second one a RAID 5 across the rest of the free space on all drives (around 2.85TB usable space). The RAID 0 I use for OS, applications and games while the RAID 5 I use as a more-permanent type storage (photos, etc). Now I do realize that running the OS and applications on RAID 0 across 5 drives is very dangerous, which is what brings up the following question. Is there a reliable freeware realtime backup application that can backup a set of folders from one drive to another drive (no online backups needed)? I've already tried a few (Mozy, Yadis, Comodo Backup, GFI Backup, Idoo, Crash Plan) but none meet my requirements: Low CPU and RAM usage. Realtime Backups - as soon as a file is modified in the source folder, it is added to the backup queue which will be processed with the lowest priority when the CPU is idle. This backup queue should persist in cases of computer restarts (ie: the source and destination folders should always have the same set of files, except for the ones waiting in the backup queue). Incremental Backups - if only 10 bytes changed in a 1GB file, the app should only copy those 10 new bytes. Ability to back up locked and opened files (some apps, like Yadis, can't back up critical files like browser favorites). Ability to run as a service (no need for any user to log-in to have the app started). Optional requirements: Compression of the destination into a well-known format (RAR, Zip) that can be directly read without the use of the application. Preset source folders (such as Browser Favorites, Game Saves, Application Settings, etc). The idea is to use RAID 0 array as "semi-persistent RAM-like" storage which in case of a failure can be quickly rebuilt by reinstalling the OS, apps and games and copying over the settings, saves, favorites from the RAID 5. I'm also thinking of taking this RAID 0 as RAM idea to the extreme with SSDs (as soon as we get some nice 6Gb/s SATA III SSDs out there), where a couple of SSDs chained in RAID 0 will work as yet another semi-persistent cache layer sitting between the RAM and the HD. I'm just hoping there already exists an application that satisfies these requirements... otherwise I'll have to write one myself, which I would prefer not to do.

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• configuration required for HIVE to be installed on a node

  - by ????? ????????

  I went through the process of manually installing ambari (not through SSH, because I couldnt get keyless to work) and everything installed OK, except for HIVE and GANGLIA. I got this message: stderr: None stdout: warning: Unrecognised escape sequence ‘\;’ in file /var/lib/ambari-agent/puppet/modules/hdp-hive/manifests/hive/service_check.pp at line 32 warning: Dynamic lookup of $configuration is deprecated. Support will be removed in Puppet 2.8. Use a fully-qualified variable name (e.g., $classname::variable) or parameterized classes. notice: /Stage[1]/Hdp::Snappy::Package/Hdp::Snappy::Package::Ln[32]/Hdp::Exec[hdp::snappy::package::ln 32]/Exec[hdp::snappy::package::ln 32]/returns: executed successfully notice: /Stage[2]/Hdp-hive::Hive::Service_check/File[/tmp/hiveserver2Smoke.sh]/ensure: defined content as ‘{md5}7f1d24221266a2330ec55ba620c015a9' notice: /Stage[2]/Hdp-hive::Hive::Service_check/File[/tmp/hiveserver2.sql]/ensure: defined content as ‘{md5}0c429dc9ae0867b5af74ef85b5530d84' notice: /Stage[2]/Hdp-hcat::Hcat::Service_check/File[/tmp/hcatSmoke.sh]/ensure: defined content as ‘{md5}bae7742f7083db968cb6b2bd208874cb’ notice: /Stage[2]/Hdp-hcat::Hcat::Service_check/Exec[hcatSmoke.sh prepare]/returns: 13/06/25 03:11:56 WARN conf.HiveConf: DEPRECATED: Configuration property hive.metastore.local no longer has any effect. Make sure to provide a valid value for hive.metastore.uris if you are connecting to a remote metastore. notice: /Stage[2]/Hdp-hcat::Hcat::Service_check/Exec[hcatSmoke.sh prepare]/returns: FAILED: SemanticException org.apache.hadoop.hive.ql.parse.SemanticException: org.apache.hadoop.hive.ql.metadata.HiveException: java.lang.RuntimeException: Unable to instantiate org.apache.hadoop.hive.metastore.HiveMetaStoreClient notice: /Stage[2]/Hdp-hcat::Hcat::Service_check/Exec[hcatSmoke.sh prepare]/returns: 13/06/25 03:12:06 WARN conf.HiveConf: DEPRECATED: Configuration property hive.metastore.local no longer has any effect. Make sure to provide a valid value for hive.metastore.uris if you are connecting to a remote metastore. notice: /Stage[2]/Hdp-hcat::Hcat::Service_check/Exec[hcatSmoke.sh prepare]/returns: FAILED: SemanticException [Error 10001]: Table not found hcatsmokeida8c07401_date102513 notice: /Stage[2]/Hdp-hcat::Hcat::Service_check/Exec[hcatSmoke.sh prepare]/returns: 13/06/25 03:12:15 WARN conf.HiveConf: DEPRECATED: Configuration property hive.metastore.local no longer has any effect. Make sure to provide a valid value for hive.metastore.uris if you are connecting to a remote metastore. notice: /Stage[2]/Hdp-hcat::Hcat::Service_check/Exec[hcatSmoke.sh prepare]/returns: FAILED: SemanticException o When i go to the alerts and health checks i’m getting this: ive Metastore status check CRIT for 42 minutes CRITICAL: Error accessing hive-metaserver status [13/06/25 03:44:06 WARN conf.HiveConf: DEPRECATED: Configuration property hive.metastore.local no longer has any effect. What am I doing wrong? I have already tried to do ambari-server reset on the the database without results.

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• VBA + Polymorphism: Override worksheet functions from 3rd party

  - by phi

  my company makes extensive use of a data provider using a (closed source) VBA plugin. In principal, every query follows follows a certain structure: Fill one cell with a formula, where arguments to the formula specify the query the range of that formula is extended (not an arrray formula!) and cells below/right are filled with data For this to work, however, a user has to have a terminal program installed on the machine, as well as a com-plugin referenced in VBA/Excel. My Problem These Excelsheets are used and extended by multiple users, and not all of them have access to the data provider. While they can open the sheet, it will recalculate and the data will be gone. However, frequent recalculation is required. I would like every user to be able to use the sheets, without executing a very specific set of formulas. Attempts remove the reference on those computers where I do not have terminal access. This generates a NAME error i the cell containing the query (acceptable), but this query overrides parts of the data (not acceptable) If you allow the program to refresh, all data will be gone after a failed query Replace all formulas with the plain-text result in the respective cells (press a button and loop over every cell...). Obviously destroys any refresh-capabilities the querys offer for all subsequent users, so pretty bad, too. A theoretical idea, and I'm not sure how to implement it: Replace the functions offered by the plugin with something that will be called either first (and relay the query through to the original function, if thats available) or instead of the original function (by only deploying the solution on non-terminal machines), which just returns the original value. More specifically, if my query function is used like this: =GETALLDATA(Startdate, Enddate, Stockticker, etc) I would like to transparently swap the function behind the call. Do you see any hope, or am I lost? I appreciate your help. PS: Of course I'm talking about Bloomberg... Some additional points to clarify issues raise by Frank: The formula in the sheets may not be changed. This is mission-critical software, and its way too complex for any sane person to try and touch it. Only excel and VBA may be used (which is the reason for the previous point...) It would be sufficient to prevent execution of these few specific formulas/functions on a specific machine for all excel sheets to come This looks more and more like a problem for stackoverflow ;-)

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