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• mdadm raid5 recover double disk failure - with a twist (drive order)

  - by Peter Bos

  Let me acknowledge first off that I have made mistakes, and that I have a backup for most but not all of the data on this RAID. I still have hope of recovering the rest of the data. I don't have the kind of money to take the drives to a recovery expert company. Mistake #0, not having a 100% backup. I know. I have a mdadm RAID5 system of 4x3TB. Drives /dev/sd[b-e], all with one partition /dev/sd[b-e]1. I'm aware that RAID5 on very large drives is risky, yet I did it anyway. Recent events The RAID become degraded after a two drive failure. One drive [/dev/sdc] is really gone, the other [/dev/sde] came back up after a power cycle, but was not automatically re-added to the RAID. So I was left with a 4 device RAID with only 2 active drives [/dev/sdb and /dev/sdd]. Mistake #1, not using dd copies of the drives for restoring the RAID. I did not have the drives or the time. Mistake #2, not making a backup of the superblock and mdadm -E of the remaining drives. Recovery attempt I reassembled the RAID in degraded mode with mdadm --assemble --force /dev/md0, using /dev/sd[bde]1. I could then access my data. I replaced /dev/sdc with a spare; empty; identical drive. I removed the old /dev/sdc1 from the RAID mdadm --fail /dev/md0 /dev/sdc1 Mistake #3, not doing this before replacing the drive I then partitioned the new /dev/sdc and added it to the RAID. mdadm --add /dev/md0 /dev/sdc1 It then began to restore the RAID. ETA 300 mins. I followed the process via /proc/mdstat to 2% and then went to do other stuff. Checking the result Several hours (but less then 300 mins) later, I checked the process. It had stopped due to a read error on /dev/sde1. Here is where the trouble really starts I then removed /dev/sde1 from the RAID and re-added it. I can't remember why I did this; it was late. mdadm --manage /dev/md0 --remove /dev/sde1 mdadm --manage /dev/md0 --add /dev/sde1 However, /dev/sde1 was now marked as spare. So I decided to recreate the whole array using --assume-clean using what I thought was the right order, and with /dev/sdc1 missing. mdadm --create /dev/md0 --assume-clean -l5 -n4 /dev/sdb1 missing /dev/sdd1 /dev/sde1 That worked, but the filesystem was not recognized while trying to mount. (It should have been EXT4). Device order I then checked a recent backup I had of /proc/mdstat, and I found the drive order. md0 : active raid5 sdb1[0] sde1[4] sdd1[2] sdc1[1] 8790402048 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU] I then remembered this RAID had suffered a drive loss about a year ago, and recovered from it by replacing the faulty drive with a spare one. That may have scrambled the device order a bit...so there was no drive [3] but only [0],[1],[2], and [4]. I tried to find the drive order with the Permute_array script: https://raid.wiki.kernel.org/index.php/Permute_array.pl but that did not find the right order. Questions I now have two main questions: I screwed up all the superblocks on the drives, but only gave: mdadm --create --assume-clean commands (so I should not have overwritten the data itself on /dev/sd[bde]1. Am I right that in theory the RAID can be restored [assuming for a moment that /dev/sde1 is ok] if I just find the right device order? Is it important that /dev/sde1 be given the device number [4] in the RAID? When I create it with mdadm --create /dev/md0 --assume-clean -l5 -n4 \ /dev/sdb1 missing /dev/sdd1 /dev/sde1 it is assigned the number [3]. I wonder if that is relevant to the calculation of the parity blocks. If it turns out to be important, how can I recreate the array with /dev/sdb1[0] missing[1] /dev/sdd1[2] /dev/sde1[4]? If I could get that to work I could start it in degraded mode and add the new drive /dev/sdc1 and let it resync again. It's OK if you would like to point out to me that this may not have been the best course of action, but you'll find that I realized this. It would be great if anyone has any suggestions.

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• unity, seeing all instances of same open application windows on all virtual desktop

  - by Nasser M. Abbasi

  I noticed this strange issue with unity. I am using 12.04. The desktop has 4 virtual desktops, which I can switch between using the 'workspace switcher' which is very nice. But I noticed the following: When I have 2 instances of the same app (say 2 different firefox windows, or 2 different terminal windows), in 2 different virtual desktops, then I click on the icon for that application located on the launcher panel (the left long strip with icons on it), then I see the application comes into focus. Then when I click again right away (on the same icon on the launcher), then now all instances of this application that are open come into ONE view (may be on was on desktop 1, and the other was on desktop 3 for example) and then I can now click on the one instance window that I want to select to use. This is all very nice actually. But this does NOT work for all applications! I just tried it, and it worked for firefox, and for gedit and for the gnome terminal. I have one firefox window open in virtual desktop 1, and another window open in virtual desktop 2. I clicked once on the firefox icon, then again, and both windows came into the main desktop and I was able to select which one to use. When I tried the same thing on dolphin file manager, which I also had 2 windows (instances) of it open in 2 different virtual desktops, this behavior did not happen. I clicked again, and nothing happened. Only one remained in focus. So I had to fo look for the second dolphin window the hard way. It looks like some apps are supported by this feature and some are not. How does one make it so that all applications are supported like this? This is a very handy feature. Is it a configuration item somewhere? thanks

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• C/C++: Who uses the logical operator macros from iso646.h and why?

  - by Jaime Soto

  There has been some debate at work about using the merits of using the alternative spellings for C/C++ logical operators in iso646.h: and && and_eq &= bitand & bitor | compl ~ not ! not_eq != or || or_eq |= xor ^ xor_eq ^= According to Wikipedia, these macros facilitate typing logical operators in international (non-US English?) and non-QWERTY keyboards. All of our development team is in the same office in Orlando, FL, USA and from what I have seen we all use the US English QWERTY keyboard layout; even Dvorak provides all the necessary characters. Supporters of using the iso646.h macros claim we should them because they are part of the C and C++ standards. I think this argument is moot since digraphs and trigraphs are also part of these standards and they are not even supported by default in many compilers. My rationale for opposing these macros in our team is that we do not need them since: Everybody on our team uses the US English QWERTY keyboard layout; C and C++ programming books from the US barely mention iso646.h, if at all; and new developers may not be familiar with iso646.h (this is expected if they are from the US). /rant Finally, to my set of questions: Does anyone in this site use the iso646.h logical operator macros? Why? What is your opinion about using the iso646.h logical operator macros in code written and maintained on US English QWERTY keyboards? Is my digraph and trigraph analogy a valid argument against using iso646.h with US English QWERTY keyboard layouts? EDIT: I missed two similar questions in StackOverflow: Is anybody using the named boolean operators? Which C++ logical operators do you use: and, or, not and the ilk or C style operators? why?

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• C#/.NET Little Wonders: The Nullable static class

  - by James Michael Hare

  Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Today we’re going to look at an interesting Little Wonder that can be used to mitigate what could be considered a Little Pitfall.  The Little Wonder we’ll be examining is the System.Nullable static class.  No, not the System.Nullable<T> class, but a static helper class that has one useful method in particular that we will examine… but first, let’s look at the Little Pitfall that makes this wonder so useful. Little Pitfall: Comparing nullable value types using <, >, <=, >= Examine this piece of code, without examining it too deeply, what’s your gut reaction as to the result? 1: int? x = null; 2:  3: if (x < 100) 4: { 5: Console.WriteLine("True, {0} is less than 100.", 6: x.HasValue ? x.ToString() : "null"); 7: } 8: else 9: { 10: Console.WriteLine("False, {0} is NOT less than 100.", 11: x.HasValue ? x.ToString() : "null"); 12: } Your gut would be to say true right?  It would seem to make sense that a null integer is less than the integer constant 100.  But the result is actually false!  The null value is not less than 100 according to the less-than operator. It looks even more outrageous when you consider this also evaluates to false: 1: int? x = null; 2:  3: if (x < int.MaxValue) 4: { 5: // ... 6: } So, are we saying that null is less than every valid int value?  If that were true, null should be less than int.MinValue, right?  Well… no: 1: int? x = null; 2:  3: // um... hold on here, x is NOT less than min value? 4: if (x < int.MinValue) 5: { 6: // ... 7: } So what’s going on here?  If we use greater than instead of less than, we see the same little dilemma: 1: int? x = null; 2:  3: // once again, null is not greater than anything either... 4: if (x > int.MinValue) 5: { 6: // ... 7: } It turns out that four of the comparison operators (<, <=, >, >=) are designed to return false anytime at least one of the arguments is null when comparing System.Nullable wrapped types that expose the comparison operators (short, int, float, double, DateTime, TimeSpan, etc.).  What’s even odder is that even though the two equality operators (== and !=) work correctly, >= and <= have the same issue as < and > and return false if both System.Nullable wrapped operator comparable types are null! 1: DateTime? x = null; 2: DateTime? y = null; 3:  4: if (x <= y) 5: { 6: Console.WriteLine("You'd think this is true, since both are null, but it's not."); 7: } 8: else 9: { 10: Console.WriteLine("It's false because <=, <, >, >= don't work on null."); 11: } To make matters even more confusing, take for example your usual check to see if something is less than, greater to, or equal: 1: int? x = null; 2: int? y = 100; 3:  4: if (x < y) 5: { 6: Console.WriteLine("X is less than Y"); 7: } 8: else if (x > y) 9: { 10: Console.WriteLine("X is greater than Y"); 11: } 12: else 13: { 14: // We fall into the "equals" assumption, but clearly null != 100! 15: Console.WriteLine("X is equal to Y"); 16: } Yes, this code outputs “X is equal to Y” because both the less-than and greater-than operators return false when a Nullable wrapped operator comparable type is null.  This violates a lot of our assumptions because we assume is something is not less than something, and it’s not greater than something, it must be equal.  So keep in mind, that the only two comparison operators that work on Nullable wrapped types where at least one is null are the equals (==) and not equals (!=) operators: 1: int? x = null; 2: int? y = 100; 3:  4: if (x == y) 5: { 6: Console.WriteLine("False, x is null, y is not."); 7: } 8:  9: if (x != y) 10: { 11: Console.WriteLine("True, x is null, y is not."); 12: } Solution: The Nullable static class So we’ve seen that <, <=, >, and >= have some interesting and perhaps unexpected behaviors that can trip up a novice developer who isn’t expecting the kinks that System.Nullable<T> types with comparison operators can throw.  How can we easily mitigate this? Well, obviously, you could do null checks before each check, but that starts to get ugly: 1: if (x.HasValue) 2: { 3: if (y.HasValue) 4: { 5: if (x < y) 6: { 7: Console.WriteLine("x < y"); 8: } 9: else if (x > y) 10: { 11: Console.WriteLine("x > y"); 12: } 13: else 14: { 15: Console.WriteLine("x == y"); 16: } 17: } 18: else 19: { 20: Console.WriteLine("x > y because y is null and x isn't"); 21: } 22: } 23: else if (y.HasValue) 24: { 25: Console.WriteLine("x < y because x is null and y isn't"); 26: } 27: else 28: { 29: Console.WriteLine("x == y because both are null"); 30: } Yes, we could probably simplify this logic a bit, but it’s still horrendous!  So what do we do if we want to consider null less than everything and be able to properly compare Nullable<T> wrapped value types? The key is the System.Nullable static class.  This class is a companion class to the System.Nullable<T> class and allows you to use a few helper methods for Nullable<T> wrapped types, including a static Compare<T>() method of the. What’s so big about the static Compare<T>() method?  It implements an IComparer compatible comparison on Nullable<T> types.  Why do we care?  Well, if you look at the MSDN description for how IComparer works, you’ll read: Comparing null with any type is allowed and does not generate an exception when using IComparable. When sorting, null is considered to be less than any other object. This is what we probably want!  We want null to be less than everything!  So now we can change our logic to use the Nullable.Compare<T>() static method: 1: int? x = null; 2: int? y = 100; 3:  4: if (Nullable.Compare(x, y) < 0) 5: { 6: // Yes! x is null, y is not, so x is less than y according to Compare(). 7: Console.WriteLine("x < y"); 8: } 9: else if (Nullable.Compare(x, y) > 0) 10: { 11: Console.WriteLine("x > y"); 12: } 13: else 14: { 15: Console.WriteLine("x == y"); 16: } Summary So, when doing math comparisons between two numeric values where one of them may be a null Nullable<T>, consider using the System.Nullable.Compare<T>() method instead of the comparison operators.  It will treat null less than any value, and will avoid logic consistency problems when relying on < returning false to indicate >= is true and so on. Tweet   Technorati Tags: C#,C-Sharp,.NET,Little Wonders,Little Pitfalls,Nulalble

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• A better way to encourage contributions to OSS

  - by Daniel Cazzulino

  Currently in the .NET world, most OSS projects are available via a NuGet package. Users have a very easy path towards *using* the project right away. But let’s say they encounter some isssue (maybe a bug, maybe a potential improvement) with the library. At this point, going from user to contributor (of a fix, or a good bug repro or even a spike for a new feature) is a very steep and non trivial multi-step process of registering with some open source hosting site (codeplex, github, bitbucket, etc.), learning how to grab the latest sources, build the project, formulate a patch (or fork the code), learn the source control software they use (mercurial, git, svn, tfs), install whatever tools are needed for it, read about the contributors workflow for the project (do you fork &amp; send pull requests? do you just send a patch file? do you just send a snippet? a unit test? etc.), and on, and on, and on. Granted, you may be lucky and already know the source control system the project uses, but in really, I’d say the chances are pretty low. I believe most developers *using* OSS are far from familiar with them, much less with contributing back to various projects. We OSS devs like to be on the cutting edge all the time, ya’ know, always jumping on the new SCC system, the new hosting site, the new agile way of managing work items, bug tracking, code reviews, etc. etc. etc.. But most of our OSS users are largely the “... Read full article

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• Can I temporarily leave other roles active when converting a 2008 R2 server to a hyper-v host?

  - by Eric

  I currently have a Windows 2008 R2 box that I want to convert to a hyper-v host. Currently I have the following running on it: File Services, Web Server (IIS), and Sql Server 2008 R2 with a few different DBs. In the long term, I'd like to move all of those over to the VMs that will be created. However, in the short term I'd like to leave them running on the server. Are there any complications/problems with leaving them running on the hyper-v server for a day or two? How long will those services typically go down during the addition of the hyper-v role? Right now my plan is to back up everything, enable the hyper-v role, set up VMs, and migrate stuff off of the host. However, if there is a good probability that something may cease to function I might need to migrate everything over to a temporary host before doing the conversion.

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• Implementing a multilanguage AI contest platform

  - by Alejandro Piad

  This is a followup to this question. To sum: I'm implementing an AI contest site, where each user may submit several AI implementations for different games. Think about Google AI Challenge but instead of just having a big event once a year, I would like it more on a league fashion, with all virtual players playing with each other every some close period of time. I want to support as many programming languages as possible. I've seen that contest sites (like codeforces) ask you to submit a source code and interact through stdin and stdout. The first question is: what is the best way of supporting multiple languages? As I see it, I can either ask people to upload some binary/script, and interact either through stdin/*stdout*, or sockets, or the file system; or ask people to submit source code, and wrap it with whatever is necessary for the interaction. I would like to skip the need to compile the code by myself (in the server, I mean), but I am willing to do it if its the "best" choice. I need to comunicate virtual players with each other, or even better, with some intermediary arbiter. The second question is regarding security. If I'm going to be running user code in my server, I want to ensure strict security conditions, like no file system access, no networking, etc. Otherwise it would be a safe heaven for hackers. I will be implementing the engine/arbiter in .NET. I would like to support at least C#, C++, Java and Python for the user's implementations. I'm willing to write interfaces for each of these languages to simplify the user interaction with the system. Thanks in advance.

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• CodePlex Daily Summary for Wednesday, June 04, 2014

  CodePlex Daily Summary for Wednesday, June 04, 2014Popular ReleasesSEToolbox: SEToolbox 01.032.018 Release 1: Added ability to merge/join two ships, regardless of origin. Added Language selection menu to set display text language (for SE resources only), and fixed inherent issues. Added full support for Dedicated Servers, allowing use on PC without Steam present, and only the Dedicated Install. Added Browse button for used specified save game selection in Load dialog. Installation of this version will replace older version.DNN Blog: 06.00.07: Highlights: Enhancement: Option to show management panel on child modules Fix: Changed SPROC and code to ensure the right people are notified of pending comments. (CP-24018) Fix: Fix to have notification actions authentication assume the right module id so these will work from the messaging center (CP-24019) Fix: Fix to issue in categories in a post that will not save when no categories and no tags selectedcsv2xlsx: Source code: Source code of applicationHigLabo: HigLabo_20140603: Bug fix of MimeParser for nested MimeContent parsing.Family Tree Analyzer: Version 4.0.0.0-beta2: This major release introduces a significant new feature the ability to search the UK Ordnance Survey 50k Gazetteer for small placenames that often don't appear on a modern Google Map. This means significant numbers of locations that were previously not found by Google Geocoding will now be found by using OS Geocoding. In addition I've added support for loading the Scottish 1930 Parish boundary maps, whilst slightly different from the parish boundaries in use in the 1800s that are familiar to...TEncoder: 4.0.0: --4.0.0 -Added: Video downloader -Added: Total progress will be updated more smoothly -Added: MP4Box progress will be shown -Added: A tool to create gif image from video -Added: An option to disable trimming -Added: Audio track option won't be used for mpeg sources as default -Fixed: Subtitle position wasn't used -Fixed: Duration info in the file list wasn't updated after trimming -Updated: FFMpegSSIS Multiple Hash: Multiple Hash 1.6.2.3: Release Notes This release is an SQL 2014 fix release. It addresses the following: The 1.6.1.2 release's SQL 2014 installer didn't work for SQL 2014 RTM. The x64 installer also showed x86 for both x64 and x86 in SQL 2014. Please download the x64 of x32 file based on the bitness of your SQL Server installation. BIDS or SSDT/BI ONLY INSTALLS ARE NOT DETECTED. You MUST use the Custom install, to install when the popup is shown, and select which versions of SQL Server are available. A war...QuickMon: Version 3.14 (Pie release): This is unofficially the 'Pie' release. There are two big changes.1. 'Presets' - basically templates. Future releases might build on this to allow users to add more presets. 2. MSI Installer now allows you to choose components (in case you don't want all collectors etc.). This means you don't have to download separate components anymore (AllAgents.zip still included in case you want to use them separately) Some other changes:1. Add/changed default file extension for monitor packs to *.qmp (...VeraCrypt: VeraCrypt version 1.0d: Changes between 1.0c and 1.0d (03 June 2014) : Correct issue while creating hidden operating system. Minor fixes (look at git history for more details).Keepass2Android: 0.9.4-pre1: added plug-in support: See settings for how to get plug-ins! published QR plug-in (scan passwords, display passwords as QR code, transfer entries to other KP2A devices) published InputStick plugin (transfer credentials to your PC via bluetooth - requires InputStick USB stick) Third party apps can now simply implement querying KP2A for credentials. Are you a developer? Please add this to your app if suitable! added TOTP support (compatible with KeeOTP and TrayTotp) app should no l...The IRIS Toolbox Project: IRIS Reference Manual Release 20140602: Reference Manual for Release 20140602.Microsoft Web Protection Library: AntiXss Library 4.3.0: Download from nuget or the Microsoft Download Center This issue finally addresses the over zealous behaviour of the HTML Sanitizer which should now function as expected once again. HTML encoding has been changed to safelist a few more characters for webforms compatibility. This will be the last version of AntiXSS that contains a sanitizer. Any new releases will be encoding libraries only. We recommend you explore other sanitizer options, for example AntiSamy https://www.owasp.org/index....Z SqlBulkCopy Extensions: SqlBulkCopy Extensions 1.0.0: SqlBulkCopy Extensions provide MUST-HAVE methods with outstanding performance missing from the SqlBulkCopy class like Delete, Update, Merge, Upsert. Compatible with .NET 2.0, SQL Server 2000, SQL Azure and more! Bulk MethodsBulkDelete BulkInsert BulkMerge BulkUpdate BulkUpsert Utility MethodsGetSqlConnection GetSqlTransaction You like this library? Find out how and why you should support Z Project Become a Memberhttp://zzzproject.com/resources/images/all/become-a-member.png|ht...Tweetinvi a friendly Twitter C# API: Tweetinvi 0.9.3.x: Timelines- Added all the parameters available from the Timeline Endpoints in Tweetinvi. - This is available for HomeTimeline, UserTimeline, MentionsTimeline // Simple query var tweets = Timeline.GetHomeTimeline(); // Create a parameter for queries with specific parameters var timelineParameter = Timeline.CreateHomeTimelineRequestParameter(); timelineParameter.ExcludeReplies = true; timelineParameter.TrimUser = true; var tweets = Timeline.GetHomeTimeline(timelineParameter); Tweetinvi 0.9.3.1...Sandcastle Help File Builder: Help File Builder and Tools v2014.5.31.0: General InformationIMPORTANT: On some systems, the content of the ZIP file is blocked and the installer may fail to run. Before extracting it, right click on the ZIP file, select Properties, and click on the Unblock button if it is present in the lower right corner of the General tab in the properties dialog. This release completes removal of the branding transformations and implements the new VS2013 presentation style that utilizes the new lightweight website format. Several breaking cha...ClosedXML - The easy way to OpenXML: ClosedXML 0.71.2: More memory and performance improvements. Fixed an issue with pivot table field order.Magick.NET: Magick.NET 6.8.9.101: Magick.NET linked with ImageMagick 6.8.9.1. Breaking changes: - Int/short Set methods of WritablePixelCollection are now unsigned. - The Q16 build no longer uses HDRI, switch to the new Q16-HDRI build if you need HDRI.fnr.exe - Find And Replace Tool: 1.7: Bug fixes Refactored logic for encoding text values to command line to handle common edge cases where find/replace operation works in GUI but not in command line Fix for bug where selection in Encoding drop down was different when generating command line in some cases. It was reported in: https://findandreplace.codeplex.com/workitem/34 Fix for "Backslash inserted before dot in replacement text" reported here: https://findandreplace.codeplex.com/discussions/541024 Fix for finding replacing...SoundCloud Downloader: SC Downloader V1.0: Newest release Requirements .NET Framework 4.0/4.5 Changes since releasing the source Replaced ProgressBar and Buttons with the ones i created from scratch, you may use the .dll files on your own risk. Changed the authentication mode to Windows NOTE! When extracted, execute setup.exe to launch the installer! NOTE! ENJOY!VG-Ripper & PG-Ripper: VG-Ripper 2.9.59: changes NEW: Added Support for 'GokoImage.com' links NEW: Added Support for 'ViperII.com' links NEW: Added Support for 'PixxxView.com' links NEW: Added Support for 'ImgRex.com' links NEW: Added Support for 'PixLiv.com' links NEW: Added Support for 'imgsee.me' links NEW: Added Support for 'ImgS.it' linksNew Projects2112110148: 2112110148 Kieu Thi Phuong AnhAutoHelp: Inspired by Docy, AutoHelp exposes XML documentation embedded in sources code. a MVC 5 / typescripted connected on Webapi, AutoHelp is a modern HTML 5 appFeedbackata: An exercise in interactive development.Ideaa: A place to get inspired and find ideas about a topic you are interested inImpression Studio - Free presentation Maker Tool: Impression Studio is a free presentation maker tool based on impress.js library. It aims to be free alternative to prezi. This tool is under heavy development.LavaMite: LavaMite is a program that aims to capture the random wax formations that arise in a lava lamp before it is bubbling freely.Load Runner - HTTP Pressure Test Tool: A Lightweight HTTP pressure test tool supports multi methods / content type / requests, written in C# 4.0.Microsoft Research Software Radio SDK: Microsoft Research Software Radio SDKMsp: MspPower Torrent: Windows PowerShell module enabling BitTorrent (R) functionalities.

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• Why do some programmers think there is a contrast between theory and practice?

  - by Giorgio

  Comparing software engineering with civil engineering, I was surprised to observe a different way of thinking: any civil engineer knows that if you want to build a small hut in the garden you can just get the materials and go build it whereas if you want to build a 10-storey house you need to do quite some maths to be sure that it won't fall apart. In contrast, speaking with some programmers or reading blogs or forums I often find a wide-spread opinion that can be formulated more or less as follows: theory and formal methods are for mathematicians / scientists while programming is more about getting things done. What is normally implied here is that programming is something very practical and that even though formal methods, mathematics, algorithm theory, clean / coherent programming languages, etc, may be interesting topics, they are often not needed if all one wants is to get things done. According to my experience, I would say that while you do not need much theory to put together a 100-line script (the hut), in order to develop a complex application (the 10-storey building) you need a structured design, well-defined methods, a good programming language, good text books where you can look up algorithms, etc. So IMO (the right amount of) theory is one of the tools for getting things done. So my question is why do some programmers think that there is a contrast between theory (formal methods) and practice (getting things done)? Is software engineering (building software) perceived by many as easy compared to, say, civil engineering (building houses)? Or are these two disciplines really different (apart from mission-critical software, software failure is much more acceptable than building failure)?

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• Alt-Tab looses focus and have to hit Alt-Grave Accent to get focus

  - by John Hamill

  Alt-Tab looses focus and have to hit Alt-Grave Accent to get focus I have ubuntu 12.4 with Unity window manager. I have a gvim window and a firefox window open. I hit Alt-Tab to switch between the two. Sometimes the gvim window doesn't have focus and I have to hit Alt-GraveAccent (Alt-`) to get the gvim window to have focus (ie: have the cursor a solid white square instead of a outline of a square) I do this to move between firefox where I highlight some text and do a copy, then Alt-Tab to gvim and do a paste. Sometimes the focus isn't in gvim and the paste doesn't work. I then have to do an Alt-graveAccent to get the focus into gvim or click the gvim window. These extra steps slow my process down and it makes it difficult to get into a smooth rythum. I saw this: ALT+TAB loses focus Maybe the Alt-GraveAccent may help someone. It's a unity bug: https://bugs.launchpad.net/ubuntu/+source/unity/+bug/1035628 Your best bet is to wait until an update comes through fixing it.

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• magento on Zend Server (Win7) installation error

  - by czerasz

  I try to install magento for the first time. I've created the database with the name "project" in my C:\Zend\Apache2\conf\httpd.conf I added on the end: <Directory "C:\Zend\Apche2\htdocs\project"> Options Indexes FollowSymLinks AllowOverride All Order allow,deny Allow from all </Directory> in my ZendServer/Server Setup/Extensions: PDO_MySQL, simplexml, mcrypt, hash, GD, DOM, iconv, curl, SOAP are on in C:\Zend\ZendServer\etc\php.ini I set: safe_mode = Off ;<-- was set to off ... memory_limit = 512M; Maximum amount of memory a script may consume (128MB) After step "Configuration" of magento installation (with Use Web Server (Apache) Rewrites enabled) I get: Internal Server Error My database is full of tables (that schould be ok) My Zend Server shows: 27-Oct 06:55 6 Severe Slow Request Execution (Absolute) http://localhost/project/index.php/install/wizard/installDb/ Critical Open 27-Oct 06:55 4 Fatal PHP Error C:\Zend\Apache2\htdocs\project\lib\Varien\Db\Adapter\Pdo\Mysql.php Critical Open 27-Oct 06:55 5 Slow Function Execution curl_exec Warning Open 27-Oct 06:55 5 Slow Request Execution (Absolute) http://localhost/project/index.php/install/wizard/configPost/ What can be wrong?

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• C# Adds Optional and Named Arguments

  Earlier this month Microsoft released Visual Studio 2010, the .NET Framework 4.0 (which includes ASP.NET 4.0), and new versions of their core programming languages: C# 4.0 and Visual Basic 10. In designing the latest versions of C# and VB, Microsoft has worked to bring the two languages into closer parity. Certain features available in C# were missing in VB, and vice-a-versa. Last week I wrote about Visual Basic 2010's language enhancements, which include implicit line continuation, auto-implemented properties, and collection initializers - three useful features that were available in previous versions of C#. Similarly, C# 4.0 introduces new features to the C# programming language that were available in earlier versions of Visual Basic, namely optional arguments and named arguments. Optional arguments allow developers to specify default values for one or more arguments to a method. When calling such a method, these optional arguments may be omitted, in which case their default value is used. In a nutshell, optional arguments allow for a more terse syntax for method overloading. Named arguments, on the other hand, improve readability by allowing developers to indicate the name of an argument (along with its value) when calling a method. This article examines how to use optional arguments and named arguments in C# 4.0. Read on to learn more! Read More >

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• C# Adds Optional and Named Arguments

  Earlier this month Microsoft released Visual Studio 2010, the .NET Framework 4.0 (which includes ASP.NET 4.0), and new versions of their core programming languages: C# 4.0 and Visual Basic 10. In designing the latest versions of C# and VB, Microsoft has worked to bring the two languages into closer parity. Certain features available in C# were missing in VB, and vice-a-versa. Last week I wrote about Visual Basic 2010's language enhancements, which include implicit line continuation, auto-implemented properties, and collection initializers - three useful features that were available in previous versions of C#. Similarly, C# 4.0 introduces new features to the C# programming language that were available in earlier versions of Visual Basic, namely optional arguments and named arguments. Optional arguments allow developers to specify default values for one or more arguments to a method. When calling such a method, these optional arguments may be omitted, in which case their default value is used. In a nutshell, optional arguments allow for a more terse syntax for method overloading. Named arguments, on the other hand, improve readability by allowing developers to indicate the name of an argument (along with its value) when calling a method. This article examines how to use optional arguments and named arguments in C# 4.0. Read on to learn more! Read More >Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Is NAN suitable for communicating that an invalid parameter was involved in a calculation?

  - by Arman

  I am currently working on a numerical processing system that will be deployed in a performance-critical environment. It takes inputs in the form of numerical arrays (these use the eigen library, but for the purpose of this question that's perhaps immaterial), and performs some range of numerical computations (matrix products, concatenations, etc.) to produce outputs. All arrays are allocated statically and their sizes are known at compile time. However, some of the inputs may be invalid. In these exceptional cases, we still want the code to be computed and we still want outputs not "polluted" by invalid values to be used. To give an example, let's take the following trivial example (this is pseudo-code): Matrix a = {1, 2, NAN, 4}; // this is the "input" matrix Scalar b = 2; Matrix output = b * a; // this results in {2, 4, NAN, 8} The idea here is that 2, 4 and 8 are usable values, but the NAN should signal to the receipient of the data that that entry was involved in an operation that involved an invalid value, and should be discarded (this will be detected via a std::isfinite(value) check before the value is used). Is this a sound way of communicating and propagating unusable values, given that performance is critical and heap allocation is not an option (and neither are other resource-consuming constructs such as boost::optional or pointers)? Are there better ways of doing this? At this point I'm quite happy with the current setup but I was hoping to get some fresh ideas or productive criticism of the current implementation.

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• Podcast Show Notes: Are You Future Proof?

  - by Bob Rhubart

  On September 14, 2012 ZDNet blogger Joe McKendrick published Why IT is a Profession in Flux, a short article in which he makes the observation that "IT professionals are under considerable pressure to deliver more value to the business, versus being good at coding and testing and deploying and integrating." I forwarded that article to my list of Usual Suspects (the nearly 40 people who have participated in the podcast over the last 3 years), along with a suggestion that I wanted to put together a panel discussion to further explore the issue. This podcast is the result. As it happened, three of the people who responded to my query were in San Francisco for Oracle OpenWorld, as was I, so I seized the rare opportunity for a face to face conversation. The participants are all Oracle ACE Directors, as well as architects: Ron Batra, Director of Cloud Computing at AT&T Basheer Khan, Founder, President and CEO at Innowave Technology Ronald van Luttikhuizen, Managing Partner at Vennster. The Conversation Listen to Part 1 Future-Proofing: As powerful forces reshape enterprise IT, your IT and software development skills may not be enough. Listen to Part 2 Survival Strategy: Re-tooling one’s skill set to reflect changes in enterprise IT, including the knowledge to steer stakeholders around the hype to what’s truly valuable. Listen to Part 3 Writing on the Wall: Do the technological trends that are shaping enterprise IT pose any threat to basic software development roles? What opportunities do these changes represent? The entire conversation is also available in video format from the OTN YouTube Channel. Your Two Cents What are you doing to future-proof your IT career? Share your thoughts in the comments section.

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• What do these "Cron Daemon" email errors mean?

  - by Meltemi

  Anyone know what this means? Getting one of these every minute in one user's inbox: From: Cron Daemon <[email protected]> Subject: Cron <joe@mail> /tmp/.d/update >/dev/null 2>&1 To: [email protected] Received: from murder ([unix socket]) by mail.domain.com (Cyrus v2.2.12-OS X 10.3) with LMTPA; Tue, 04 May 2010 10:35:00 -0700 shell-init: could not get current directory: getcwd: cannot access parent directories: Permission denied job-working-directory: could not get current directory: getcwd: cannot access parent directories: Permission denied

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• EPPM Webcast Series Part II: Build – Consistently delivering successful projects to ensure financial success

  - by Sylvie MacKenzie, PMP

  Oracle Primavera invites you to the second in a series of three webcasts linking Enterprise Project Portfolio Management with enhanced operational performance and better financial results. Join us for the next installment of our 'Plan, Build, Operate' webcast series, as we look to address the challenges organizations face during the execution phase of their projects. Webcast II: Build – Consistently delivering successful projects to ensure financial success. This webcast will look at Three key questions: How do you maintain consistency in delivery whilst maintaining visibility and control? How do you deal with project risk and mitigation strategies? How do you ensure accurate reporting? Hear from Geoff Roberts, Industry Strategist from Oracle Primavera. Geoff will look at how solutions can help to address the challenges around: Visibility and governance Communication and complex coordination Collecting and reporting progress Measuring and reporting It is imperative that organizations understand the impact projects can have on their business. Attend this webcast and understand how consistently delivering successful projects is vital to the financial success of an asset intensive organisation. Register today! Please forward this invite to your colleagues who you think may benefit from attending.

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• Installation of Tex Live via the terminal 12.04

  - by user74713

  I need to install upstream version of TeX Live for 12.04 to edit the manual for Ubuntu. I am having a difficult time installing it per the directions @ http://ubuntu-manual.org/getinvolved/editors#install-texlive. TeX Live documents are on my computer, but I am not able to run the install. No TeX Live program found on my computer. Any help is greatly appreciated! ~Thanx!~ Hello, my name is Chris. I am a student pursuing a career in technical writing. I would like to assist the Ubuntu community while gaining experience & building my resume. Below I have listed the prior attempts & links to view the posts of each attempt: Backports I have tried using the official backports of the latest (2012) TeX-Live via their PPA. Please refer to link below for the particulars. How do I install the latest 2012 TeX Live on 12.04? Latex I've also tried running Latex as suggested. Please refer to link below for the particulars. http://ubuntuforums.org/showthread.php?t=2019051 PPA Causing Issue?? or something else I came across a post concerning the ability to install programs via the terminal and am wondering if it may be my problem??? Please refer to link below for the particulars. PPA - TeX Live Cannot install anything through Terminal - apt-get -f install

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• Oracle Enterprise Manager 12c Configuration Best Practices (Part 3 of 3)

  - by Bethany Lapaglia

  <span id="XinhaEditingPostion"></span>&amp;lt;span id=&amp;quot;XinhaEditingPostion&amp;quot;&amp;gt;&amp;lt;/span&amp;gt;&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;span id=&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;XinhaEditingPostion&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/span&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; This is part 3 of a three-part blog series that summarizes the most commonly implemented configuration changes to improve performance and operation of a large Enterprise Manager 12c environment. A “large” environment is categorized by the number of agents, targets and users. See the Oracle Enterprise Manager Cloud Control Advanced Installation and Configuration Guide chapter on Sizing for more details on sizing your environment properly. Part 1 of this series covered recommended configuration changes for the OMS and Repository Part 2 covered recommended changes for the Weblogic server Part 3 covers general configuration recommendations and a few known issues The entire series can be found in the My Oracle Support note titled Oracle Enterprise Manager 12c Configuration Best Practices [1553342.1]. Configuration Recommendations Configure E-Mail Notifications for EM related Alerts In some environments, the notifications for events for different target types may be sent to different support teams (i.e. notifications on host targets may be sent to a platform support team). However, the EM application administrators should be well informed of any alerts or problems seen on the EM infrastructure components. Recommendation: Create a new Incident rule for monitoring all EM components and setup the notifications to be sent to the EM administrator(s). The notification methods available can create or update an incident, send an email or forward to an event connector. To setup the incident rule set follow the steps below. Note that each individual rule in the rule set can have different actions configured. 1.  To create an incident rule for monitoring the EM components, click on Setup / Incidents / Incident Rules. On the All Enterprise Rules page, click on the out-of-box rule called “Incident management Ruleset for all targets” and then click on the Actions drop down list and select “Create Like Rule Set…” 2. For the rule set name, enter a name such as MTM Ruleset. Under the Targets tab, select “All targets of types” and select “OMS and Repository” from the drop down list. This target type contains all of the key EM components (OMS servers, repository, domains, etc.) 3. Click on the Rules tab. To edit a rule, click on the rule name and click on Edit as seen below 4. Modify the following rules: a. Incident creation Rule for metric alerts i. Leave the Type set as is but change the Severity to add Warning by clicking on the drop down list and selecting “Warning”. Click Next. ii.  Add or modify the actions as required (i.e. add email notifications). Click Continue and then click Next. iii. Leave the Name and description the same and click Next. iv. Click Continue on the Review page. b. Incident creation Rule for target unreachable. i.   Leave the Type set as is but change the Target type to add OMS and Repository by clicking on the drop down list selecting “OMS and Repository”. Click Next. ii.  Add or modify the actions as required (i.e. add email notifications) Click Continue and then click Next. iii. Leave the Name and description the same and click Next. iv. Click Continue on the Review page. 5.  Modify the actions for any other rule as required and be sure to click the “Save” push button to save the rule set or all changes will be lost. Configure Out-of-Band Notifications for EM Agent Out-of-Band notifications act as a backup when there’s a complete EM outage or a repository database issue. This is configured on the agent of the OMS server and can be used to send emails or execute another script that would create a trouble ticket. It will send notifications about the following issues: • Repository Database down • All OMS are down • Repository side collection job that is broken or has an invalid schedule • Notification job that is broken or has an invalid schedule Recommendation: To setup Out-of-Band Notifications, refer to the MOS note “How To Setup Out Of Bound Email Notification In 12c” (Doc ID 1472854.1) Modify the Performance Test for the EM Console Service The EM Console Service has an out-of-box defined performance test that will be run to determine the status of this service. The test issues a request via an HTTP method to a specific URL. By default, the HTTP method used for this test is a GET but for performance reasons, should be changed to HEAD. The URL used for this request is set to point to a specific OMS server by default. If a multi-OMS system has been implemented and the OMS servers are behind a load balancer, then the URL in this section must be modified to point to the load balancer name instead of a specific server name. If this is not done and a portion of the infrastructure is down then the EM Console Service will show down as this test will fail. Recommendation: Modify the HTTP Method for the EM Console Service test and the URL if required following the detailed steps below. 1.  To create an incident rule for monitoring the EM components, click on Targets / Services. From the list of services, click on the EM Console Service. 2. On the EM Console Service page, click on the Test Performance tab. 3.  At the bottom of the page, click on the Web Transaction test called EM Console Service Test 4.  Click on the Service Tests and Beacons breadcrumb near the top of the page. 5.  Under the Service Tests section, make sure the EM Console Service Test is selected and click on the Edit push button. 6.  Under the Transaction section, make sure the Access Logout page transaction is selected and click on the Edit push button 7) Under the Request section, change the HTTP Method from the default of GET to the recommended value of HEAD. The URL in this section must be modified to point to the load balancer name instead of a specific server name if multi-OMSes have been implemented. Check for Known Issues Job Purge Repository Job is Shown as Down This issue is caused after upgrading EM from 12c to 12cR2. On the Repository page under Setup ? Manage Cloud Control ? Repository, the job called “Job Purge” is shown as down and the Next Scheduled Run is blank. Also, repvfy reports that this is a missing DBMS_SCHEDULER job. Recommendation: In EM 12cR2, the apply_purge_policies have been moved from the MGMT_JOB_ENGINE package to the EM_JOB_PURGE package. To remove this error, execute the commands below: $ repvfy verify core -test 2 -fix To confirm that the issue resolved, execute $ repvfy verify core -test 2 It can also be verified by refreshing the Job Service page in EM and check the status of the job, it should now be Up. Configure the Listener Targets in EM with the Listener Password (where required) EM will report this error every time it is encountered in the listener log file. In a RAC environment, typically the grid home and rdbms homes are owned by different OS users. The listener always runs from the grid home. Only the listener process owner can query or change the listener properties. The listener uses a password to allow other OS users (ex. the agent user) to query the listener process for parameters. EM has a default listener target metric that will query these properties. If the agent is not permitted to do this, the TNS incident (TNS-1190) will be logged in the listener’s log file. This means that the listener targets in EM also need to have this password set. Not doing so will cause many TNS incidents (TNS-1190). Below is a sample of this error from the listener log file: Recommendation: Set a listener password and include it in the configuration of the listener targets in EM For steps on setting the listener passwords, see MOS notes: 260986.1 , 427422.1

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• EPM 11.1.2.2 Architecture: Essbase

  - by Marc Schumacher

  Since a lot of components exist to access or administer Essbase, there are also a couple of client tools available. End users typically use the Excel Add-In or SmartView nowadays. While the Excel Add-In talks to the Essbase server directly using various ports, SmartView connects to Essbase through Provider Services using HTTP protocol. The ability to communicate using a single port is one of the major advantages from SmartView over Excel Add-In. If you consider using Excel Add-In going forward, please make sure you are aware of the Statement of Direction for this component. The Administration Services Console, Integration Services Console and Essbase Studio are clients, which are mainly used by Essbase administrators or application designers. While Integration Services and Essbase Studio are used to setup Essbase applications by loading metadata or simply for data loads, Administration Services are utilized for all kind of Essbase administration. All clients are using only one or two ports to talk to their server counterparts, which makes them work through firewalls easily. Although clients for Provider Services (SmartView) and Administration Services (Administration Services Console) are only using a single port to communicate to their backend services, the backend services itself need the Essbase configured port range to talk to the Essbase server. Any communication to repository databases is done using JDBC connections. Essbase Studio and Integration Services are using different technologies to talk to the Essbase server, Integration Services uses CAPI, Essbase Studio uses JAPI. However, both are using the configured port range on the Essbase server to talk to Essbase. Connections to data sources are either based on ODBC (Integration Service, Essbase) or JDBC (Essbase Studio). As for all other components discussed previously, when setting up firewall rules, be aware of the fact that all services may need to talk to the external authentication sources, this is not only needed for Shared Services.

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• Pythonic Java. Yes, or no?

  - by OscarRyz

  Python use of indentation for code scope was initially very polemic and now is considered one of the best language features, because it helps ( almost by forcing us ) to have a consistent style. Well, I saw this post http://bit.ly/hmvTe9 where someone posted Java code with ; y {} aligned to the right margin to look more pythonic. It was very shocking at first ( as a matter of fact, if I ever see Java code like that in one of my projects I would be scared! ) However, there is something interesting here. Do we need all those braces and semicolons? How would the code would look like without them? class Person int age void greet( String a ) if( a == "" ) out.println("Hello stranger") else out.printf("Hello %s%n", a ) int age() return this.age class Main void main() new Person().greet("") Looks good to me, but in such small piece of code is hard to appreciate it, and since I don't Python too much, I can't tell by looking at existing libraries if it would be cleaner or not. So I took the first file of a library named: jAlarms I found and this is the result: ( WARNING : the following image may be disturbing for some people ) http://pxe.pastebin.com/eU1R4xsh Obviously it doesn't compile. This would be a compiling version using right aligned {} and ; http://pxe.pastebin.com/2uijtbYM Question What would happen if we could code like this? Would it make things clearer? Would it make it harder? I see braces, and semicolons as help to the parser and we, as humans have get used to them, but do we really need them? I guess is hard to tell specially since many mainstream languages do use braces, C, C++, Java, C# JavaScript Assuming the compiler wouldn't have problems without them, would you use them? Please comment.

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• C IDE for Mac needed

  - by StasM

  I'm looking for heavy-duty C/C++ IDE for Mac that would satisfy the following criteria: Work with big projects (~5000 files, some of them 100K big) efficiently. Have good navigation both file-based and symbol-based - i.e. "go to file", "go to function" etc. with autocompletion support. Support for "go to declaration/definition" for symbols - functions, structures, etc. Auto-adding new files in folders already in the project. Support for code completion for values, function names, etc. At least rudimentary CPP macro understanding - i.e. #define foo bar then foo() should take me either to #define or to actual bar. I understand full CPP parsing may be hard, but I hope for at least the obvious cases. Support for displaying parameter names/types by function name, preferably - integrated with the previous item, for functions defined in the project. Support for libc would be nice too :) (optional) Cross-project search support (I can manage with grep -r if everything else works) (optional) SVN support, at least to some extent (update, commit, mark updated) Is there such editor around? Free would be nice, but I'm ready to part with some money if it's good enough. I'm using TextMate now but I'm not satisfied with it. Tried Xcode but it seems to not be able to handle a large project - it just crashed...

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• File format for animated scene

  - by stephelton

  I've got a custom OpenGL based rendering engine and I'd like to add support for cinema-type scene animation. The artist that is helping me uses primarily 3DSMax. I'd like a file format for exporting and importing this data. I'm also in need of a file format for skeletal animation data, which may have an impact here. I've been looking at MAXScript to manually export this stuff, which would buy me the most flexibility, but I have virtually no experience with 3DSMax itself, so I get a little lost when it comes to terminology. So I'd like to know what file formats exist for animated scene data, and whether they are appropriate for my use (my fear is that they will be way too broad for my fairly simple needs.) The way I view animated scene data is basically a bunch of references to [animated] models with keyframe-based matrices describing their orientation over time. And probably some special camera stuff to handle perspective. I might also want some event type stuff for adding/removing objects. Is this a sane concept?

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• Can SATA be used to connect computers?

  - by André

  Can SATA be used to connect two computers together, just like a crossover Ethernet cable would do ? I know SATA has no "networking" features and even though a controller may have multiple ports, the drives don't "see" each other, and that in SATA one device acts as the host (the computer) and the other device is some kind of "client" (the storage drive). But still, did anyone attempt to make a kernel module that would make one computer appear as a "client" (so that the host's SATA controller detects it as a standard hard drive) and then set up like a pseudo-Ethernet link or a very high speed serial link (and then run pppd on it and do networking) ? Note : I know this is an unprofessional and totally stupid idea, I'm just asking out of curiosity.

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• limit linux background flush (dirty pages)

  - by korkman

  Background flushing in linux happens when either too much written data is pending (adjustable via /proc/sys/vm/dirty_background_ratio) or a timeout for pending writes is reached (/proc/sys/vm/dirty_expire_centisecs). Unless another limit is being hit (/proc/sys/vm/dirty_ratio), more written data may be cached. Further writes will block. In theory, this should create a background process writing out dirty pages without disturbing other processes. In practice, it does disturb any process doing uncached reading or synchronous writing. Badly. This is because the background flush actually writes at 100% device speed and any other device requests at this time will be delayed (because all queues and write-caches on the road are filled). Is there any way to limit the amount of requests per second the flushing process performs, or otherwise effectively prioritize other device I/O?

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