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• How to get more information from the system crash

  - by viraptor

  I'd like to debug an issue I'm having with a linux (debian stable) server, but I'm running out of ideas of how to confirm any diagnosis. Some background: The servers are running DL160 class with hardware raid between two disks. They're running a lot of services, mostly utilising network interface and CPU. There are 8 cpus and 7 "main" most cpu-hungry processes are bound to one core each via cpu affinity. Other random background scripts are not forced anywhere. The filesystem is writing ~1.5k blocks/s the whole time (goes up above 2k/s in peak times). Normal CPU usage for those servers is ~60% on 7 cores and some minimal usage on the last (whatever's running on shells usually). What actually happens is that the "main" services start using 100% CPU at some point, mainly stuck in kernel time. After a couple of seconds, LA goes over 400 and we lose any way to connect to the box (KVM is on it's way, but not there yet). Sometimes we see a kernel reporting hung task (but not always): [118951.272884] INFO: task zsh:15911 blocked for more than 120 seconds. [118951.272955] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [118951.273037] zsh D 0000000000000000 0 15911 1 [118951.273093] ffff8101898c3c48 0000000000000046 0000000000000000 ffffffffa0155e0a [118951.273183] ffff8101a753a080 ffff81021f1c5570 ffff8101a753a308 000000051f0fd740 [118951.273274] 0000000000000246 0000000000000000 00000000ffffffbd 0000000000000001 [118951.273335] Call Trace: [118951.273424] [<ffffffffa0155e0a>] :ext3:__ext3_journal_dirty_metadata+0x1e/0x46 [118951.273510] [<ffffffff804294f6>] schedule_timeout+0x1e/0xad [118951.273563] [<ffffffff8027577c>] __pagevec_free+0x21/0x2e [118951.273613] [<ffffffff80428b0b>] wait_for_common+0xcf/0x13a [118951.273692] [<ffffffff8022c168>] default_wake_function+0x0/0xe .... This would point at raid / disk failure, however sometimes the tasks are hung on kernel's gettsc which would indicate some general weird hardware behaviour. It's also running mysql (almost read-only, 99% cache hit), which seems to spawn a lot more threads during the system problems. During the day it does ~200kq/s (selects) and ~10q/s (writes). The host is never running out of memory or swapping, no oom reports are spotted. We've got many boxes with similar/same hardware and they all seem to behave that way, but I'm not sure which part fails, so it's probably not a good idea to just grab something more powerful and hope the problem goes away. Applications themselves don't really report anything wrong when they're running. I can run anything safely on the same hardware in an isolated environment. What can I do to narrow down the problem? Where else should I look for explanation?

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• Building a Data Warehouse

  - by Paul

  I've seen tutorials articles and posts on how to build datawarehouses with star and snowflakes schemas, denormalization of OLTP databases fact and dimension tables and so on. Also seen comments like: Star schemas are for datamarts, at best. There is absolutely no way a true enterprise data warehouse could be represented in a star schema, or snowflake either. I want to create a database that will server for reporting services and maybe (if that isn't enough) install analisys services and extract reports and data from cubes. My question was : Is it really necesarry to redesign my current database and follow the star/snowflake schemas with fact and dimension tables ? Thank you

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• Best tool for Analyzing IIS 7 SMTP Logs

  - by EfficionDave

  We're using IIS 7's SMTP service for sending out emails from our sites. I'm looking for a SMTP Log analyzer to make it easier for me to view the results and identify and problems (Blocks, Unauthorized relay attempts, blacklisting, ...). What is the best tool to use for this?

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• Finding the most common errors in event logs using Powershell.

  - by Paul

  I have the event logs for one of our servers locally in .evtx format. I can load the log file into PS using the command: Get-WinEvent -Path D:\Desktop\serverlogs.evtx What I would like to do is on the Message field group events where the text matches by a certain percent (say 80% the same). As we have stacktraces for errors in the details which will be the same, but we also log the client's IP, url that was accessed which will likely be different. I want to group them so that I can work out the most common errors to prioritize fixing them and as there are 25,000+ errors in the log file I would rather not do it manually. I think I can work out how to do most of this, but am not sure how I could do the 'group fields which are mostly the same' part, does powershell have anything like this built in?

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• What does it mean that most dropped packets have a different incoming and outgoing port?

  - by Kev

  Over the weekend an internet-facing DI-624 router of mine was e-mailing me logs like crazy for some reason. Normally it's a few a day, but it was about one every few minutes instead. Analyzing the messages, I found that only 340 had the same src and dst port number, whereas the majority of "default deny" dropped packets (28,000+) had the two ports different. What does this mean?

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• Why would my mouse pointer be jerky when it can't get a signal from my router?

  - by izb

  I've got a fairly new PC but when moving the mouse across the screen, the pointer jerks as if the PC is freezing momentarily every second or so. Strangely, this only seems to happen if the signal from the wifi router is bad. If I move the PC closer to the router to get a full signal, it's fine. It also seems to affect the keyboard; Opening notepad and holding down a key shows the same momentary freezes. -- Update: It's a logitech wireless mouse, and a wired USB logitech keyboard.

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• Linux monitor logs and email alerts?

  - by Physikal

  I have a server with a faulty power button that likes to reboot itself. Usually there are warning signs, like the acpid log file in /var/log starts spamming garbage for about 10hrs or so. Is there an easy way I can have something monitor the acpid log and email me when it has new activity? I wouldn't consider myself extremely advanced so any "guides" you may have for accomplishing something like this would be very helpful and much appreciated. Thank you!

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• Sun Directory Server 5.2 performance

  - by tmow

  Hi all, I'm using logconv.pl (provided by Sun), to measure performance on my server. These two metrics results, are worrying me a bit: Binds: 192164 Unbinds: 111569 In fact the difference between the two it's quite big, how can I determine which are the unbound requests? As stated by Lodovic: Many applications just close the connections without sending an Unbind request. This simply can explain the difference. But the logconv.pl doesn't show details about the unbound requests, do you know any other tools or can you suggest some queries or whatever that can help me find out the root cause? Do you think anyway that the performances may improve fixing the issue?

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• In Wireshark's Protocol Hierarchy Statistics screen, is the total byte count of a capture the sum of the Bytes column or just the top line (Frame)?

  - by Howiecamp

  Part 1 - I'm looking at Wireshark's Protocol Hierarchy Statistics screen (sample below), is the total byte count of the capture the sum of the Bytes column or just the top line (Frame)? I'm 99% that it's the latter because of protocol rollup but I wanted to conform. Part 2 - From Wireshark documentation on this screen, "Protocol layers can consist of packets that won't contain any higher layer protocol, so the sum of all higher layer packets may not sum up to the protocols packet count. Example: In the screenshot TCP has 85,83% but the sum of the subprotocols (HTTP, ...) is much less. This may be caused by TCP protocol overhead, e.g. TCP ACK packets won't be counted as packets of the higher layer)." Can you explain this?

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• list and explanations of ways to boost this router's signal strength? [closed]

  - by barlop

  Possible Duplicates: Improve Wireless Signal How to get wireless coverage over my whole house? What's the best way to increase the range of my 802.11g router? The back of my house doesn't have WiFi Signal I'm interested in ways that are both specific to certain routers, and generic. When I say generic, I don't necessarily mean a one way that works for many.. but it can also be a generic answer, so mentioning solutions for different situations. So not just the one router I mention. Explanations are important, as well as all the ways. One i'm particularly interested in boosting the strength of is this wireless router/modem Netgear VMDG280 maybe anywhere in a big house with three floors, maybe from the garden.

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• Tool to collect stacktraces in server logs

  - by hstoerr

  Is there a tool collect and count all different stacktraces in a bunch of server logfiles? Sometimes you have just too many stacktraces that repeat over and over. So it can be difficult to spot different problems between the stacktraces. So the idea would be to have a tool that looks for stacktraces, compares them and counts them. It would be nice if the tool could ignore minor differences (e.g. $Proxy150.dispatchCalls() versus $Proxy25.dispatchCalls() ).

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• FxCop CA2227 warning and ReadOnlyCollection<T>

  - by brickner

  In my VS2008 SP1, .NET 3.5 SP1 project, I have different classes that contain different properties. I use C#3.0 auto properties a lot. Some of these properties need to be collections. Since I want to make it simple, I use ReadOnlyCollection<T for these properties. I don't want to use IEnumerable<T since I want random access to the elements. I use Code Analysis (FxCop rules) and I get the CA2227 warning. I don't understand why does ReadOnlyCollection<T should have a set method while it can't be changed... The set method can only do exactly what the property can do. Example: using System.Collections.ObjectModel; namespace CA2227 { public class MyClass { public ReadOnlyCollection<int> SomeNumbers { get; set; } } } CA2227 : Microsoft.Usage : Change 'MyClass.SomeNumbers' to be read-only by removing the property setter. C:\Users...\Visual Studio 2008\Projects\CA2227\MyClass.cs 7 CA2227

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• Should I suppress CA1062: Validate arguments of public methods?

  - by brickner

  I've recently upgraded my project to Visual Studio 2010 from Visual Studio 2008. In Visual Studio 2008, this Code Analysis rule doesn't exist. Now I'm not sure if I should use this rule or not. I'm building an open source library so it seems important to keep people safe from doing mistakes. However, if all I'm going to do is throw ArgumentNullException when the parameter is null, it seems like writing useless code since ArgumentNullException will be thrown even if I won't write that code. Should I remove that rule or fix the violations?

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• DataMining / Analyzing responses to Multiple Choice Questions in a survey

  - by Shailesh Tainwala

  Hi, I have a set of training data consisting of 20 multiple choice questions (A/B/C/D) answered by a hundred respondents. The answers are purely categorical and cannot be scaled to numerical values. 50 of these respondents were selected for free product trial. The selection process is not known. What interesting knowledge can be mined from this information? The following is a list of what I have come up with so far- A study of percentages (Example - Percentage of people who answered B on Qs.5 and got selected for free product trial) Conditional probabilities (Example - What is the probability that a person will get selected for free product trial given that he answered B on Qs.5) Naive Bayesian classifier (This can be used to predict whether a person will be selected or not for a given set of values for any subset of questions). Can you think of any other interesting analysis or data-mining activities that can be performed? The usual suspects like correlation can be eliminated as the response is not quantifiable/scoreable. Is my approach correct?

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• Should I supress CA1062: Validate arguments of public methods?

  - by brickner

  I've recently upgraded my project to Visual Studio 2010 from Visual Studio 2008. In Visual Studio 2008, this Code Analysis rule doesn't exist. Now I'm not sure if I should use this rule or not. I'm building an open source library so it seems important to keep people safe from doing mistakes. However, if all I'm going to do is throw ArgumentNullException when the parameter is null, it seems like writing useless code since ArgumentNullException will be thrown even if I won't write that code. Should I remove that rule or fix the violations?

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• How to properly rewrite ASSERT code to pass /analyze in msvc?

  - by Sorin Sbarnea

  Visual Studio added code analysis (/analyze) for C/C++ in order to help identify bad code. This is quite a nice feature but when you deal with and old project you may be overwhelmed by the number of warnings. Most of the problems are generating because the old code is doing some ASSERT at the beginning of the method or function. I think this is the ASSERT definition used in the code (from afx.h) #define ASSERT(f) DEBUG_ONLY((void) ((f) || !::AfxAssertFailedLine(THIS_FILE, __LINE__) || (AfxDebugBreak(), 0))) Example code: ASSERT(pBytes != NULL); *pBytes = 0; // <- warning C6011: Dereferencing NULL pointer 'pBytes' I'm looking for an easy and safe solution to solve these warnings that does not imply disabling these warnings. Did I mention that there are lots of occurrences in current codebase?

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• Using "Show values as" option in Excel 2007 pivot table when source is SSAS cube?

  - by Brad

  I have an Excel 2007 pivot table showing "Year" across the top and "Month" down the side. What I am trying to do is represent the values as "% Difference" from the same month of the previous year. (Ex. If Jan-07 is $100,000 and Jan-08 is $120,000, I would like Jan-08 to show '20%'). However, every time I try to do this (using the "Show values as" tab of Value Field Settings) all of my numbers go to '#N/A'. Is there a way to do this using an Analysis Services cube as the data source? When I do this exact same thing using data on a different sheet as the data source for the pivot table, it works fine. Thanks in advance for any insight into this.

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• Utilise Surv object in ggplot or lattice

  - by Misha

  Anyone know how to take advantage of ggplot or lattice in doing survival analysis? It would be nice to do trellis/facet like survival graphs. So in the end I played around and sort of found a solution for a kaplan meier plot. Apologize for the messy code in taking the list elements into a dataframe, but I couldnt figure out another way. Note: It only works with two levels of stratum. If anyone know how I can use x<-length(stratum) to do this please let me know (in stata I could append to a macro-unsure how this works in R)... ggkm<-function(time,event,stratum) { m2s<-Surv(time,as.numeric(event)) fit <- survfit(m2s ~ stratum) f$time<-fit$time f$surv<-fit$surv f$strata<-c(rep(names(fit$strata[1]),fit$strata[1]),rep(names(fit$strata[2]),fit$strata[2])) f$upper<-fit$upper f$lower<-fit$lower r<-ggplot (f,aes(x=time,y=surv,fill=strata,group=strata))+geom_line()+geom_ribbon(aes(ymin=lower,ymax=upper),alpha=0.3) return(r) }

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• Visualize compiler warnings

  - by christoffer

  I'm looking for a way to visualize compiler warnings and remarks, by annotating or otherwise showing which lines cause a report. This is much like a modern IDE like NetBeans or Eclipse already does, but I'd like to take output from several compilers (and other static code analysis tools) at once, and create one single annotation in order to get a better overview. The rationale is that we've seen some problems go completely undetected by, say, Visual Studio 2005, but accurately detected with a proprietary ARM compiler, and vice versa. Cross-referencing warnings could potentially locate problems better, but doing so completely manually is infeasible. Have you heard of such a tool? Could an open-source IDE like Eclipse be extended to use several compilers at once, or has it already been done?

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• Is there a way to circumvent CA1726:UsePreferredTerms?

  - by klausbyskov

  I have a problem with the code analysis rule CA1726:UsePreferredTerms. Our business domain has two crucial concepts named Case and Flag. According to CA, it's apparently a deadly sin to use these names, however I really don't care since, as I said, they are crucial concepts in our domain model. CA complains not only about the type declarations but about every method parameter-name aswell. So does anyone know if there is a workaround other than adding loads of suppressions or disabling the rule altogether? Could I add the names to a custom dictionary?

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• matlab fit exp2

  - by HelloWorld

  I'm unsuccessfully looking for documentation of fit function using exp2 (sum of 2 exponents). How to operate the function is clear: [curve, gof] = fit(x, y,'exp2'); But since there are multiple ways to fit a sum of exponents I'm trying to find out what algorithm is used. Particularly what happens when I'm fitting one exponent (the raw data) with a bit of noise, how the exponents are spread. I've simulated several cases, and it seems that it "drops" all the weight on the second set of coefficients, but row data analysis often shows different behavior. Does anyone have suggestions of documentation?

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• Determining Connections between data in a single table

  - by user1689749

  Hi I'm a BA / programmer type doing data analysis on a legacy system. I've been teaching myself SQL to help, but I've appeared to hit upon a problem bigger than my abilities. I have two tables (generalized for simplicity): Table Objects Object_PK Table Components Component_PK Object_FK Component_Type There are 100+ distinct values in Component_Type_Code. Given that any object can have N number of Components, how can I see which Component_Type(s) appear with other Component_Type(s)? For example, the following query tells me what component_types appear with the component_type 'Component_type_1': select component_type_code, count(*) from components where object_fk in ( select object_fk from components where component_type_code = 'component_type_1' ) group by component_type_code I'd like to get a query to show me all connections My apologies for the formatting. Any help is appreciated. I've looked at cube and rollup, but didn't know how to apply to this situtation.

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• how to deal with a static analyzer output

  - by Jim

  We have started using a static analyzer (Coverity) on our code base. We were promptly stupefied by the sheer amount of warnings we received (its in the hundreds of thousands) , it will take the entire team a few mounts to clear them all (obliviously impossible). the options we discussed so far are 1) hire a contractor to sort out the warning and fix them - he drawback: we will probably need very experiences people to do all these modifications, and no contractor will have required understanding of the code. 2) filter out the warning and deal only with the dangerous ones - the problem here is that our static analysis output will always be cluttered by warning making it difficult for us to isolate problems. also the filtering of the warning is also a major effort. either way, bringing our code to a state when the static analyzer can be a useful tool for us seems a monumental task. so how is it possible to work with the static analyzer without braining current development efforts into a complete stand still?

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• Why do I get CA1811 when I call a private method from a public method in C++/CLI?

  - by brickner

  I've recently upgraded my project from Visual Studio 2008 to Visual Studio 2010. By enabling Code Analysis and building on Release, I'm getting warning CA1811: Avoid uncalled private code. I've managed to reduce the code to this: .h file: public ref class Foo { public: virtual System::String^ ToString() override; private: static System::String^ Bar(); }; .cpp file: String^ Foo::ToString() { return Bar(); } String^ Foo::Bar() { return "abc"; } The warning I get: CA1811 : Microsoft.Performance : 'Foo::Bar(void)' appears to have no upstream public or protected callers. It doesn't matter if Bar() is static or not. I've tried to reproduce it in C# but I can't. I can only reproduce it in C++/CLI. Why do I get this warning? Is this a Visual Studio 2010 bug?

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• How can I load an MP3 or similar music file for display and anaysis in wxWdigets?

  - by Jon Cage

  I'm developing a GUI in wxPython which allows a user to generate sequences of colours for some toys I'm building. Part of the program needs to load an MP3 (and potentially other formats further down the line) and display it to the user. That shuold be sufficient to get started but later I'd like to add features like identifying beats and some crude frequency analysis. Is there any simple way of loading / understanding an MP3's contents to display a plot of it's amplitudes to the screen using wxWidgets? I later intend to port to C++/wxWidgets for speed and to avoid having to distribute wxPython.

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