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• Storing a pass-by-reference parameter as a pointer - Bad practice?

  - by Karl Nicoll

  I recently came across the following pattern in an API I've been forced to use: class SomeObject { public: // Constructor. SomeObject(bool copy = false); // Set a value. void SetValue(const ComplexType &value); private: bool m_copy; ComplexType *m_pComplexType; ComplexType m_complexType; }; // ------------------------------------------------------------ SomeObject::SomeObject(bool copy) : m_copy(copy) { } // ------------------------------------------------------------ void SomeObject::SetValue(const ComplexType &value) { if (m_copy) m_complexType.assign(value); else m_pComplexType = const_cast<ComplexType *>(&value); } The background behind this pattern is that it is used to hold data prior to it being encoded and sent to a TCP socket. The copy weirdness is designed to make the class SomeObject efficient by only holding a pointer to the object until it needs to be encoded, but also provide the option to copy values if the lifetime of the SomeObject exceeds the lifetime of a ComplexType. However, consider the following: SomeObject SomeFunction() { ComplexType complexTypeInstance(1); // Create an instance of ComplexType. SomeObject encodeHelper; encodeHelper.SetValue(complexTypeInstance); // Okay. return encodeHelper; // Uh oh! complexTypeInstance has been destroyed, and // now encoding will venture into the realm of undefined // behaviour! } I tripped over this because I used the default constructor, and this resulted in messages being encoded as blank (through a fluke of undefined behaviour). It took an absolute age to pinpoint the cause! Anyway, is this a standard pattern for something like this? Are there any advantages to doing it this way vs overloading the SetValue method to accept a pointer that I'm missing? Thanks!

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• Any good reason to open files in text mode?

  - by Tinctorius

  (Almost-)POSIX-compliant operating systems and Windows are known to distinguish between 'binary mode' and 'text mode' file I/O. While the former mode doesn't transform any data between the actual file or stream and the application, the latter 'translates' the contents to some standard format in a platform-specific manner: line endings are transparently translated to '\n' in C, and some platforms (CP/M, DOS and Windows) cut off a file when a byte with value 0x1A is found. These transformations seem a little useless to me. People share files between computers with different operating systems. Text mode would cause some data to be handled differently across some platforms, so when this matters, one would probably use binary mode instead. As an example: while Windows uses the sequence CR LF to end a line in text mode, UNIX text mode will not treat CR as part of the line ending sequence. Applications would have to filter that noise themselves. Older Mac versions only use CR in text mode as line endings, so neither UNIX nor Windows would understand its files. If this matters, a portable application would probably implement the parsing by itself instead of using text mode. Implementing newline interpretation in the parser might also remove some overhead of using text mode, as buffers would need to be rewritten (and possibly resized) before returning to the application, while this may be less efficient than when it would happen in the application instead. So, my question is: is there any good reason to still rely on the host OS to translate line endings and file truncation?

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• What is the best way to store a table in C++

  - by Topo

  I'm programming a decision tree in C++ using a slightly modified version of the C4.5 algorithm. Each node represents an attribute or a column of your data set and it has a children per possible value of the attribute. My problem is how to store the training data set having in mind that I have to use a subset for each node so I need a quick way to only select a subset of rows and columns. The main goal is to do it in the most memory and time efficient possible (in that order of priority). The best way I have thought of is to have an array of arrays (or std::vector), or something like that, and for each node have a list (array, vector, etc) or something with the column,line(probably a tuple) pairs that are valid for that node. I now there should be a better way to do this, any suggestions? UPDATE: What I need is something like this: In the beginning I have this data: Paris 4 5.0 True New York 7 1.3 True Tokio 2 9.1 False Paris 9 6.8 True Tokio 0 8.4 False But for the second node I just need this data: Paris 4 5.0 New York 7 1.3 Paris 9 6.8 And for the third node: Tokio 2 9.1 Tokio 0 8.4 But with a table of millions of records with up to hundreds of columns. What I have in mind is keep all the data in a matrix, and then for each node keep the info of the current columns and rows. Something like this: Paris 4 5.0 True New York 7 1.3 True Tokio 2 9.1 False Paris 9 6.8 True Tokio 0 8.4 False Node 2: columns = [0,1,2] rows = [0,1,3] Node 3: columns = [0,1,2] rows = [2,4] This way on the worst case scenario I just have to waste size_of(int) * (number_of_columns + number_of_rows) * node That is a lot less than having an independent data matrix for each node.

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• which technology or strategy a new / inexperienced freelancer should use to earn profit? [closed]

  - by w3softdev

  this question has re-posted by me in the following group if you find suitable to answer this question then please click on the link attached here or copy paste this in your browser.. http://answers.onstartups.com/questions/32767/which-technology-or-strategy-a-new-inexperienced-freelancer-should-use-to-earn Well it is my very first Question in this section and i really don't know whether my query relate to this section or not. anyway i have some awkward query. (however, it is like a bit story but i guess it is necessary to know some background knowledge of me.) Actually I m fresh recent grad who has just started his freelancing work. In due course i have got a project to develop website for a middle scale business (travel agent). As I don't trust on my client whether he will pay to me in full or not after the completion of website, i want to use cheaper and efficient technology so that how much he would pay I could got at least few units of % of profit. As i have learnt ASP.NET and when I inquired about the expense in Hosting of my website i got the recommendation to develop my web app using the combination PHP and MYSQL instead the asp.net + ms sql. And the problem is I don't know PHP. should I learn PHP and or work in what i m comfortable with and should try to cover whole deserved money. (as it is my first project so i m also advised that i may got some loss in starting but contrary to this i don't want to go in loss and want to earn appropriate profit)

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• Don't speak to the DBA while he/she is doing the job?!

  - by Uri Dimant

  Our DBA was very busy today, he helped out our developers to write efficient code,explained to the programmer how to launch the old DTS package on SQL Server 2005 and etc. You know how it is, someone comes in and asking the question and you answer the question at the same time you are busy to do something. So  today answering one of such questions he deleted by mistake very ctitical database. Fortunately, we had zero data loss,thanks to our backup/recovery strategy. I think that is acceptable to say that you are busy right now ,please ask the question later on, what do you think? How do you respond if someone asks you a queston while you are doing something on the server/database and etc.?   Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Using the Coherence ConcurrentMap Interface (Locking API)

  - by jpurdy

  For many developers using Coherence, the first place they look for concurrency control is the com.tangosol.util.ConcurrentMap interface (part of the NamedCache interface). The ConcurrentMap interface includes methods for explicitly locking data. Despite the obvious appeal of a lock-based API, these methods should generally be avoided for a variety of reasons: They are very "chatty" in that they can't be bundled with other operations (such as get and put) and there are no collection-based versions of them. Locks do directly not impact mutating calls (including puts and entry processors), so all code must make explicit lock requests before modifying (or in some cases reading) cache entries. They require coordination of all code that may mutate the objects, including the need to lock at the same level of granularity (there is no built-in lock hierarchy and thus no concept of lock escalation). Even if all code is properly coordinated (or there's only one piece of code), failure during updates that may leave a collection of changes to a set of objects in a partially committed state. There is no concept of a read-only lock. In general, use of locking is highly discouraged for most applications. Instead, the use of entry processors provides a far more efficient approach, at the cost of some additional complexity.

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• Trying to sort the coefficients of the polynomial (z-a)(z-b)(z-c)...(z-n) into a vector

  - by pajamas

  So I have a factored polynomial of the form (z-a)(z-b)(z-c)...(z-n) for n an even positive integer. Thus the coefficient of z^k for 0 <= k < n will be the sum of all distinct n-k element products taken from the set {a,b,...,n} multiplied by (-1)^k, I hope that makes sense, please ask if you need more clarification. I'm trying to put these coefficients into a row vector with the first column containing the constant coefficient (which would be abc...n) and the last column containing the coefficient for z^n (which would be 1). I imagine there is a way to brute force this with a ton of nested loops, but I'm hoping there is a more efficient way. This is being done in Matlab (which I'm not that familiar with) and I know Matlab has a ton of algorithms and functions, so maybe its got something I can use. Can anyone think of a way to do this? Example: (z-1)(z-2)(z-3) = z^3 - (1 + 2 + 3)z^2 + (1*2 + 1*3 + 2*3)z - 1*2*3 = z^3 - 6z^2 + 11z - 6. Note that this example is n=3 odd, but n=4 would have taken too long to do by hand. Edit: Let me know if you think this would be better posted at TCS or Math Stack Exchange.

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• designing solution to dynamically load class

  - by dot

  Background Information I have a web app that allows end users to connect to ssh-enabled devices and manipulate them. Right now, i only support one version of firmware. The logic is something like this: user clicks on a button to run some command on device. web application looks up the class name containing the correct ssh interface for the device, using the device's model name. (because the number of hardware models is so small, i have a list that's hardcoded in my web app) web app creates a new ssh object using the class loaded in step 2. ssh command is run and session closed. command results displayed on web page. This all works fine. Now the end user wants me to be able to support multiple versions of firmware. But the catch is, they don't want to have to document the firmware version anywhere becuase the amount of overhead this will create in maintaining the system database. In other words, I can't look up the firmware version based on the device. The good news is that it sounds like at most, I'll have to support two different versions of firmware per device. One option is to name the the classes like this: deviceX.1.php deviceX.2.php deviceY.1.php deviceY.2.php where "X" and "Y" represent the model names, and 1 and 2 represent the firmware versions. When a user runs a command, I will first try it with one of the class files, if it fails, i can try with the second. I think always try the newer version of firmware first... so let's say in the above example, I would load deviceX.2.php before deviceX.1.php. This will work, but it's not very efficient. But I can't think of another way around this. Any suggestions?

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• Should developers do their own software releases (if there is a prod support team in place)?

  - by leora

  I know there are going to always be differences depending on the particular size, staff etc, but i wanted to get feedback in general around: In an environment where you have a production support team doing first line support and release management, is it better to simply have developers manage their own releases instead? In this case, its internal software at an insurance company but the question should be valid at any company, size, etc I think. Currently, we have our production team do releases but there is an argument that its inefficient and that if you allowed developers the ability to do it, they will focus more on making it simple and efficient and avoid basically passing on scripts, etc to run to another team. The counter argument is that if you don't have a check and balance, you could get a software team (or an individual) that doesn't a very hacky job about getting their software out there (making on the fly changes, not documenting the process, etc) and that by forcing the prod support team to do the actual release, it enforces consistency and proper checks and balances. I know this is not a black or white issue but I wanted to see what folks thought on this so the discipline and consistency is there but without the feeling that an inefficient process is in place.

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• how to speed up this code? [migrated]

  - by dot

  I have some code that's taking over 3 seconds to complete. I'm just wondering if there's a faster way to do this. I have a string with anywhere from 10 to 70 rows of data. I break it up into an array and then loop through the array to find specific patterns. $this->_data = str_replace(chr(27)," ",$this->_data,$count);//strip out esc character $this->_data = explode("\r\n", $this->_data); $detailsArray = array(); foreach ($this->_data as $details) { $pattern = '/(\s+)([0-9a-z]*)(\s+)(100\/1000T|10|1000SX|\s+)(\s*)(\|)(\s+)(\w+)(\s+)(\w+)(\s+)(\w+)(\s+)(1000FDx|10HDx|100HDx|10FDx|100FDx|\s+)(\s*)(\w+)(\s*)(\w+|\s+)(\s*)(0)/i'; if (preg_match($pattern, $details, $matches)) { array_push($detailsArray, array( 'Port' => $matches[2], 'Type' => $matches[4], 'Alert' => $matches[8], 'Enabled' => $matches[10], 'Status' => $matches[12], 'Mode' => $matches[14], 'MDIMode' => $matches[16], 'FlowCtrl' => $matches[18], 'BcastLimit' => $matches[20])); }//end if }//end for $this->_data = $detailsArray; Just wondering if you think there's a way to make it more efficient. Thanks.

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• Windows: what is the difference between DEP always on and DEP opt-out with no exceptions?

  - by Peter Mortensen

  What is the difference between DEP always on ("/NoExecute=AlwaysOn" in boot.ini) and DEP opt-out ( "/NoExecute=OptOut" in boot.ini) with no exceptions? "no exceptions" = empty list of programs for which DEP does not apply. DEP = Data Execution Prevention (hardware). One would expect it to work the same way, but it makes a difference for some applications. E.g. for all versions of UltraEdit 14 (14.2). It crashes at startup for DEP always on, at least on Microsoft Windows XP Professional Edition x64 edition. (2010-03-11: this problem has been fixed with UltraEdit 15.2 and later.) Update 1: I think this difference is caused by the backdoors that Microsoft has put into hardware DEP for OptOut, according to Fabrice Roux (see below). In the case of IrfanView, for which Steve Gibson observed the same difference as I did for UltraEdit (see below), the difference is caused by a non-DEP aware EXE packer (ASPack) that Microsoft coded a backdoor for. Is there a difference between Windows XP, Windows Vista and Windows 7 ? Is there a difference between 32 bit and 64 bit versions of Windows ? Sources: From [http://blog.fabriceroux.com/index.php/2007/02/26/hardware_dep_has_a_backdoor?blog=1], "Hardware DEP has a backdoor" by Fabrice Roux. 2007-02-26. "IrfanView was not using any trick to evade DEP ... Microsoft just coded a backdoor used only in OPTOUT. Bascially Microsoft checks the executable header for a section matching one of the 3 strings. If one these strings is found, DEP will be turned OFF for this application by windows. ... 'aspack', 'pcle', 'sforce'" From [http://www.grc.com/sn/sn-078.htm], by Steve Gibson. "I can’t find any documentation on Microsoft’s site anywhere, because we’re seeing a difference between always-on and opt-out. That is, you would imagine that always-on mode would be the same as opting out if you weren’t having any opt-out programs. It turns out it’s not the case. For example ... the IrfanView file viewer ... runs fine in opt-out mode, even if it has not been opted out. But it won’t launch, Windows blocks it from launching ... in always-on mode." From [http://www.grc.com/sn/sn-083.htm], by Steve Gibson. "... IrfanView ... won’t run with DEP turned on. It’s because it uses an EXE packer, an executable compression program called ASPack. And it makes sense that it wouldn’t because naturally an executable compressor has got to decompress the executable, so it allocates a bunch of data memory into which it decompresses the compressed executable, and then it runs it. Well, it’s running a data allocation, which is exactly what DEP is designed to stop. On the other hand, UPX, which is actually the leading and most popular EXE compressor, it’s DEP- compatible because those guys realized, hey, when we allocate this memory, we should mark the pages as executable."

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• DHCPDISCOVER requests from an off-by-one MAC address

  - by Aleksandr Levchuk

  In a Linux DHCP server I'm getting a bunch of these log lines: dhcpd: DHCPDISCOVER from 00:30:48:fe:5c:9c via eth1: network 192.168.2.0/24: no free leases I don't have any machines with 00:30:48:fe:5c:9c and I don't intend to give out an IP to 00:30:48:fe:5c:9c (whatever that could be). I tracked down the server that this is coming from and killed all the DHCP clients that were running but the DHCPDISCOVER requests do not stop. I can prove that this is the sending server by pulling the Ethernet cable - the requests stop. The strange thing is that the sending server only has 2 interfaces which are: 00:30:48:fe:5c:9a 00:30:48:fe:5c:9b What can be the cause of the off-by-one address? Who could be sending the requests? Details On the DHCP client: root@n34:~# ip link 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 100 link/ether 00:30:48:fe:5c:9a brd ff:ff:ff:ff:ff:ff 3: eth1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN qlen 1000 link/ether 00:30:48:fe:5c:9b brd ff:ff:ff:ff:ff:ff 4: ib0: <BROADCAST,MULTICAST> mtu 2044 qdisc noop state DOWN qlen 256 link/infiniband 80:00:00:48:fe:80:00:00:00:00:00:00:00:02:c9:03:00:08:81:9f brd 00:ff:ff:ff:ff:12:40:1b:ff:ff:00:00:00:00:00:00:ff:ff:ff:ff 5: ib1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 2044 qdisc pfifo_fast state UP qlen 256 link/infiniband 80:00:00:49:fe:80:00:00:00:00:00:00:00:02:c9:03:00:08:81:a0 brd 00:ff:ff:ff:ff:12:40:1b:ff:ff:00:00:00:00:00:00:ff:ff:ff:ff Same info: root@n34:~# ifconfig -a eth0 Link encap:Ethernet HWaddr 00:30:48:fe:5c:9a inet addr:192.168.2.234 Bcast:192.168.2.255 Mask:255.255.255.0 inet6 addr: fe80::230:48ff:fefe:5c9a/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:72544 errors:0 dropped:0 overruns:0 frame:0 TX packets:152773 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:4908592 (4.6 MiB) TX bytes:89815782 (85.6 MiB) Memory:dfd60000-dfd80000 eth1 Link encap:Ethernet HWaddr 00:30:48:fe:5c:9b UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Memory:dfde0000-dfe00000 ib0 Link encap:UNSPEC HWaddr 80-00-00-48-FE-80-00-00-00-00-00-00-00-00-00-00 BROADCAST MULTICAST MTU:2044 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:256 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) ib1 Link encap:UNSPEC HWaddr 80-00-00-49-FE-80-00-00-00-00-00-00-00-00-00-00 inet addr:192.168.3.234 Bcast:192.168.3.255 Mask:255.255.255.0 inet6 addr: fe80::202:c903:8:81a0/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:2044 Metric:1 RX packets:1330 errors:0 dropped:0 overruns:0 frame:0 TX packets:255 errors:0 dropped:5 overruns:0 carrier:0 collisions:0 txqueuelen:256 RX bytes:716415 (699.6 KiB) TX bytes:17584 (17.1 KiB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:8 errors:0 dropped:0 overruns:0 frame:0 TX packets:8 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:560 (560.0 B) TX bytes:560 (560.0 B) The nodes were imaged with Perseus which uses kexec instead of rebooting.

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• Ubuntu server random hangups.

  - by Ebbe

  Hello all. this is my first post to this forum which I found through the superb podcast "It Conversations" from StackOverFlow. I am quite in my role as server administrator for an exhibition center in London. Basically we have a central file and sql server to which roughly 40 stations connects to to upload/download data used/captured by a set of applications. Over the last weeks we have experienced a few random hangups to our applications, and as it always happen to multiple applications simultaneously I do not believe that the applications are the source of the problem. We also monitor the network using Dartware Intermapper which indicates that all switches and stations on the network has been reachable during the downtime. Thus, its all pointing to the server. I have been looking through all log files I can think of and the only thing so far that I have found suspicious is the following lines in the syslog which are from the time of one of the hangups: Feb 6 17:14:27 es named[5582]: client 127.0.0.1#33721: RFC 1918 response from Internet for 150.0.168.192.in-addr.arpa Feb 6 17:14:40 es named[5582]: client 127.0.0.1#32899: RFC 1918 response from Internet for 152.0.168.192.in-addr.arpa Feb 6 17:15:01 es /USR/SBIN/CRON[1956]: (es) CMD (/home/es/apps/es/bin/es_checksum.sh) Feb 6 17:16:06 es /USR/SBIN/CRON[2031]: (es) CMD (/home/es/apps/es/bin/es_checksum.sh) Feb 6 17:21:00 es named[5582]: *** POKED TIMER *** Feb 6 17:21:00 es last message repeated 2 times Feb 6 17:21:07 es named[5582]: client 127.0.0.1#44194: RFC 1918 response from Internet for 143.0.168.192.in-addr.arpa Feb 6 17:21:12 es named[5582]: client 127.0.0.1#59004: RFC 1918 response from Internet for 164.0.168.192.in-addr.arpa I find a few lines of interesting lines here: 1) "RFC 1918 response from Internet for 150.1.168.192.in-addr.arpa". I see this a lot in the syslog. And basically everytime I do a nslookup for any of the computers in the cluster I get a new similar line in the syslog. I understand from google that this has to do with reverse lookup problems. But I do not know how that could effect the systems. Lets say that one of these lines appear every time one of the userstations connects to the server, which may happen several times a second. Could this possible cause a hangup of the entire server? 2) POKED TIMER, I have googled this quite a lot, but not found an explaination that I can relate to. What does this mean? 3) The timestamps, it seems like the entire server has stopped responding for several minutes. Normally there are many printouts to the syslog per minute on this server. Furthermore the CRON job is set to run once every minute. Which according to the log, hasent happened here. OS: Ubuntu 8.04 Kernel: Linux 2.6.24-24-server x86_64 GNU/Linux. Hardware: Dell R710, RAID1, CPU: 2x XEON E5530. 16GB Memory. Average load is very low, and memory should not be a problem. Please let me know if you need any additional information. Best wishes, Ebbe

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• PC: Quick Freeze, then BSOD, then forced reboot, then freezes again

  - by cr0z3r

  Lately I have been experiencing a weird issue. My PC will hang for a second and then BSOD - it stays there, so I have to reboot. Once Windows starts again and I'm logged in, after 1-10min it freezes again, this time without BSOD. RECAP: 1 second freeze BSOD, hangs there I have to force-reboot Once PC rebooted, I log back into Windows second freeze between a 1-10min range, no BSOD (alternatively, I get a freeze with a constant sound/noise, no BSOD) I contacted my PC provider, who told me my graphics-card might be flawed (Quadro 4000), so I used a Quadro 2000 that they lend me. The issue still occurred. The issue now seemed to belong to a flawed RAM module. Following my provider's steps, I removed all but the first from the left column and kept using my PC for a week or so without any issues. I then added the bottom-right module, and so on, until all modules were back inside - I had no problems. Now it seemed that a simple take-out-put-back-in of the RAM modules had fixed the issue. However, after a few months, the issue was back. I redid all the RAM-swapping I had done before, and concluded that the lower-right module was flawed. My provider changed it for another, and everything was great until now. My PC froze again for barely a second, hanged on a BSOD, I rebooted it, logged-in to Windows to get a freeze (without BSOD or reboot) 40 seconds later. Something worth noting, is that every time I reboot after the BSOD, it is something within Chrome that freezes my PC (e.g. this time I clicked the "restore" button as Chrome mentioned it had exited unexpectedly - from the previous freeze obviously - and it instantly froze). Finally, the Event Viewer lists 2 critical events in the past hour as "ID: 41, Type: Kernel-Power". PC-Specs: http://i.imgur.com/VZpbr.jpg Previous Dump-files: https://dl.dropbox.com/u/716600/DumpFiles_08_2012.zip I would like to thank anybody in advance for your help. You're great. UPDATE 1: I realized that I did not mention an awkward fact about this issue. After I have gotten the 1-sec freeze followed by a BSOD, after I rebooted because the BSOD hanged, and after I logged back in to get another (this time, eternal) freeze and rebooted once again, the PC does not boot back up. The power-light is on, but my monitor says "no signal", as if the PC wouldn't really be turned on. This truly seems a like a power-related issue, doesn't it? UPDATE 2: I just got a freeze, but without BSOD. My screen froze (while on Chrome, which is starting to seem suspicious to me) with an ongoing sound/noise. I had to force-reboot my PC. I would say this is a graphics-card issue, but this issue also happened when I was using the Quadro 2000 from my provider. UPDATE 3: I just got a BSOD while trying to render something (quite heavy, actually) in 3ds Max 2012. I left the BSOD "running", as it said it was writing dump files to disk. However, the percentage number stayed at 0, so after 15 minutes I force-rebooted. I then used the software WhoCrashed (thank you Dave) which reported the following from the C:\Windows\Memory.dmp file: On Thu 22.11.2012 22:13:45 GMT your computer crashed crash dump file: C:\Windows\memory.dmp uptime: 01:05:27 This was probably caused by the following module: Unknown () Bugcheck code: 0x124 (0x0, 0xFFFFFA80275AC028, 0xF200001F, 0x100B2) Error: WHEA_UNCORRECTABLE_ERROR Bug check description: This bug check indicates that a fatal hardware error has occurred. This bug check uses the error data that is provided by the Windows Hardware Error Architecture (WHEA). This is likely to be caused by a hardware problem problem. This problem might be caused by a thermal issue. A third party driver was identified as the probable root cause of this system error. It is suggested you look for an update for the following driver: Unknown . Google query: Unknown WHEA_UNCORRECTABLE_ERROR

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• Improving TCP performance over a gigabit network with lots of connections and high traffic of small packets

  - by MinimeDJ

  I’m trying to improve my TCP throughput over a “gigabit network with lots of connections and high traffic of small packets”. My server OS is Ubuntu 11.10 Server 64bit. There are about 50.000 (and growing) clients connected to my server through TCP Sockets (all on the same port). 95% of of my packets have size of 1-150 bytes (TCP header and payload). The rest 5% vary from 150 up to 4096+ bytes. With the config below my server can handle traffic up to 30 Mbps (full duplex). Can you please advice best practice to tune OS for my needs? My /etc/sysctl.cong looks like this: kernel.pid_max = 1000000 net.ipv4.ip_local_port_range = 2500 65000 fs.file-max = 1000000 # net.core.netdev_max_backlog=3000 net.ipv4.tcp_sack=0 # net.core.rmem_max = 16777216 net.core.wmem_max = 16777216 net.core.somaxconn = 2048 # net.ipv4.tcp_rmem = 4096 87380 16777216 net.ipv4.tcp_wmem = 4096 65536 16777216 # net.ipv4.tcp_synack_retries = 2 net.ipv4.tcp_syncookies = 1 net.ipv4.tcp_mem = 50576 64768 98152 # net.core.wmem_default = 65536 net.core.rmem_default = 65536 net.ipv4.tcp_window_scaling=1 # net.ipv4.tcp_mem= 98304 131072 196608 # net.ipv4.tcp_timestamps = 0 net.ipv4.tcp_rfc1337 = 1 net.ipv4.ip_forward = 0 net.ipv4.tcp_congestion_control=cubic net.ipv4.tcp_tw_recycle = 0 net.ipv4.tcp_tw_reuse = 0 # net.ipv4.tcp_orphan_retries = 1 net.ipv4.tcp_fin_timeout = 25 net.ipv4.tcp_max_orphans = 8192 Here are my limits: $ ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 193045 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1000000 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 1000000 [ADDED] My NICs are the following: $ dmesg | grep Broad [ 2.473081] Broadcom NetXtreme II 5771x 10Gigabit Ethernet Driver bnx2x 1.62.12-0 (2011/03/20) [ 2.477808] bnx2x 0000:02:00.0: eth0: Broadcom NetXtreme II BCM57711E XGb (A0) PCI-E x4 5GHz (Gen2) found at mem fb000000, IRQ 28, node addr d8:d3:85:bd:23:08 [ 2.482556] bnx2x 0000:02:00.1: eth1: Broadcom NetXtreme II BCM57711E XGb (A0) PCI-E x4 5GHz (Gen2) found at mem fa000000, IRQ 40, node addr d8:d3:85:bd:23:0c [ADDED 2] ethtool -k eth0 Offload parameters for eth0: rx-checksumming: on tx-checksumming: on scatter-gather: on tcp-segmentation-offload: on udp-fragmentation-offload: off generic-segmentation-offload: on generic-receive-offload: on large-receive-offload: on rx-vlan-offload: on tx-vlan-offload: on ntuple-filters: off receive-hashing: off [ADDED 3] sudo ethtool -S eth0|grep -vw 0 NIC statistics: [1]: rx_bytes: 17521104292 [1]: rx_ucast_packets: 118326392 [1]: tx_bytes: 35351475694 [1]: tx_ucast_packets: 191723897 [2]: rx_bytes: 16569945203 [2]: rx_ucast_packets: 114055437 [2]: tx_bytes: 36748975961 [2]: tx_ucast_packets: 194800859 [3]: rx_bytes: 16222309010 [3]: rx_ucast_packets: 109397802 [3]: tx_bytes: 36034786682 [3]: tx_ucast_packets: 198238209 [4]: rx_bytes: 14884911384 [4]: rx_ucast_packets: 104081414 [4]: rx_discards: 5828 [4]: rx_csum_offload_errors: 1 [4]: tx_bytes: 35663361789 [4]: tx_ucast_packets: 194024824 [5]: rx_bytes: 16465075461 [5]: rx_ucast_packets: 110637200 [5]: tx_bytes: 43720432434 [5]: tx_ucast_packets: 202041894 [6]: rx_bytes: 16788706505 [6]: rx_ucast_packets: 113123182 [6]: tx_bytes: 38443961940 [6]: tx_ucast_packets: 202415075 [7]: rx_bytes: 16287423304 [7]: rx_ucast_packets: 110369475 [7]: rx_csum_offload_errors: 1 [7]: tx_bytes: 35104168638 [7]: tx_ucast_packets: 184905201 [8]: rx_bytes: 12689721791 [8]: rx_ucast_packets: 87616037 [8]: rx_discards: 2638 [8]: tx_bytes: 36133395431 [8]: tx_ucast_packets: 196547264 [9]: rx_bytes: 15007548011 [9]: rx_ucast_packets: 98183525 [9]: rx_csum_offload_errors: 1 [9]: tx_bytes: 34871314517 [9]: tx_ucast_packets: 188532637 [9]: tx_mcast_packets: 12 [10]: rx_bytes: 12112044826 [10]: rx_ucast_packets: 84335465 [10]: rx_discards: 2494 [10]: tx_bytes: 36562151913 [10]: tx_ucast_packets: 195658548 [11]: rx_bytes: 12873153712 [11]: rx_ucast_packets: 89305791 [11]: rx_discards: 2990 [11]: tx_bytes: 36348541675 [11]: tx_ucast_packets: 194155226 [12]: rx_bytes: 12768100958 [12]: rx_ucast_packets: 89350917 [12]: rx_discards: 2667 [12]: tx_bytes: 35730240389 [12]: tx_ucast_packets: 192254480 [13]: rx_bytes: 14533227468 [13]: rx_ucast_packets: 98139795 [13]: tx_bytes: 35954232494 [13]: tx_ucast_packets: 194573612 [13]: tx_bcast_packets: 2 [14]: rx_bytes: 13258647069 [14]: rx_ucast_packets: 92856762 [14]: rx_discards: 3509 [14]: rx_csum_offload_errors: 1 [14]: tx_bytes: 35663586641 [14]: tx_ucast_packets: 189661305 rx_bytes: 226125043936 rx_ucast_packets: 1536428109 rx_bcast_packets: 351 rx_discards: 20126 rx_filtered_packets: 8694 rx_csum_offload_errors: 11 tx_bytes: 548442367057 tx_ucast_packets: 2915571846 tx_mcast_packets: 12 tx_bcast_packets: 2 tx_64_byte_packets: 35417154 tx_65_to_127_byte_packets: 2006984660 tx_128_to_255_byte_packets: 373733514 tx_256_to_511_byte_packets: 378121090 tx_512_to_1023_byte_packets: 77643490 tx_1024_to_1522_byte_packets: 43669214 tx_pause_frames: 228 Some info about SACK: When to turn TCP SACK off?

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• What Apache/PHP configurations do you know and how good are they?

  - by FractalizeR

  Hello. I wanted to ask you about PHP/Apache configuration methods you know, their pros and cons. I will start myself: ---------------- PHP as Apache module---------------- Pros: good speed since you don't need to start exe every time especially in mpm-worker mode. You can also use various PHP accelerators in this mode like APC or eAccelerator. Cons: if you are running apache in mpm-worker mode, you may face stability issues because every glitch in any php script will lead to unstability to the whole thread pool of that apache process. Also in this mode all scripts are executed on behalf of apache user. This is bad for security. mpm-worker configuration requires PHP compiled in thread-safe mode. At least CentOS and RedHat default repositories doesn't have thread-safe PHP version so on these OSes you need to compile at least PHP yourself (there is a way to activate worker mpm on Apache). The use of thread-safe PHP binaries is considered experimental and unstable. Plus, many PHP extensions does not support thread-safe mode or were not well-tested in thread-safe mode. ---------------- PHP as CGI ---------------- This seems to be the slowest default configuration which seems to be a "con" itself ;) ---------------- PHP as CGI via mod_suphp ---------------- Pros: suphp allows you to execute php scipts on behalf of the script file owner. This way you can securely separate different sites on the same machine. Also, suphp allows to use different php.ini files per virtual host. Cons: PHP in CGI mode means less performance. In this mode you can't use php accelerators like APC because each time new process is spawned to handle script rendering the cache of previous process useless. BTW, do you know the way to apply some accelerator in this config? I heard something about using shm for php bytecode cache. Also, you cannot configure PHP via .htaccess files in this mode. You will need to install PECL htscanner for this if you need to set various per-script options via .htaccess (php_value / php_flag directives) ---------------- PHP as CGI via suexec ---------------- This configuration looks the same as with suphp, but I heard, that it's slower and less safe. Almost same pros and cons apply. ---------------- PHP as FastCGI ---------------- Pros: FastCGI standard allows single php process to handle several scripts before php process is killed. This way you gain performance since no need to spin up new php process for each script. You can also use PHP accelerators in this configuration (see cons section for comment). Also, FCGI almost like suphp also allows php processes to be executed on behalf of some user. mod_fcgid seems to have the most complete fcgi support and flexibility for apache. Cons: The use of php accelerator in fastcgi mode will lead to high memory consumption because each PHP process will have his own bytecode cache (unless there is some accelerator that can use shared memory for bytecode cache. Is there such?). FastCGI is also a little bit complex to configure. You need to create various configuration files and make some configuration modifications. It seems, that fastcgi is the most stable, secure, fast and flexible PHP configuration, however, a bit difficult to be configured. But, may be, I missed something? Comments are welcome!

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• Why the server is not responding?

  - by par

  Hello! Our server occasionally refuses to serve a simple HTML page. This is happening during a relatively high number of requests. However, the processor is not heavy loaded and there are a lot of free memory. The error seems to occure 1 out of 50 requests in average, depending on the server load. I need to find the source of the problem and take the appropriate actions to eliminate it. I have a suspicion that the problem source is a huge number of incoming network packets. There are 5000 packets per second on average. Traffic - 2 MBits/sec Can this be the cause of the error? There is an interesting thing, in case the server fails to respond, the request string is not logged to access.log by Apache. The error is repeatable from several client computers. DNS is not involved, since I have accessed the server by the IP. I have profiled the problem case with tcpdump utility. These are the good and bad sessions traced by tcpdump. The request is the same in both experiments. Good - server returns response. Bad - no response, time-out error. ---- Bad ---- 12:23:36.366292 IP 123.45.67.890.61749 > myserver.superbservers.com.www: S 2125316338:2125316338(0) win 8192 <mss 1460,nop,wscale 2,nop,nop,sackOK> 12:23:39.362394 IP 123.45.67.890.61749 > myserver.superbservers.com.www: S 2125316338:2125316338(0) win 8192 <mss 1460,nop,wscale 2,nop,nop,sackOK> 12:23:45.365567 IP 123.45.67.890.61749 > myserver.superbservers.com.www: S 2125316338:2125316338(0) win 8192 <mss 1460,nop,nop,sackOK> -------- ---- Good ---- 12:27:07.632229 IP 123.45.67.890.63914 > myserver.superbservers.com.www: S 3581365570:3581365570(0) win 8192 <mss 1460,nop,wscale 2,nop,nop,sackOK> 12:27:10.620946 IP 123.45.67.890.63914 > myserver.superbservers.com.www: S 3581365570:3581365570(0) win 8192 <mss 1460,nop,wscale 2,nop,nop,sackOK> 12:27:10.620969 IP myserver.superbservers.com.www > 123.45.67.890.63914: S 2654770980:2654770980(0) ack 3581365571 win 5840 <mss 1460,nop,nop,sackOK,nop,wscale 6> 12:27:10.838747 IP 123.45.67.890.63914 > myserver.superbservers.com.www: . ack 1 win 4380 12:27:10.957143 IP 123.45.67.890.63914 > myserver.superbservers.com.www: P 1:213(212) ack 1 win 4380 12:27:10.957152 IP myserver.superbservers.com.www > 123.45.67.890.63914: . ack 213 win 108 12:27:10.965543 IP myserver.superbservers.com.www > 123.45.67.890.63914: P 1:630(629) ack 213 win 108 12:27:10.965621 IP myserver.superbservers.com.www > 123.45.67.890.63914: F 630:630(0) ack 213 win 108 12:27:11.183540 IP 123.45.67.890.63914 > myserver.superbservers.com.www: . ack 631 win 4222 12:27:11.185657 IP 123.45.67.890.63914 > myserver.superbservers.com.www: F 213:213(0) ack 631 win 4222 12:27:11.185663 IP myserver.superbservers.com.www > 123.45.67.890.63914: . ack 214 win 108 -------- Hoster: SuperbHosting OS: Ubuntu Server parameters: E6300 CONROE 1.86GHZ 2 X 1MB CACHE 1066 1GB DDR2 667MHZ This is a link to apache configuration file we use http://repkin5.snow.prohosting.com/apache.txt This is server-status report taken right after time-out error. http://repkin5.snow.prohosting.com/server-status.htm There are only 10 Child Servers running out of 120, so enough space for new requests. VMSTAT procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 8900 725900 8468 65684 0 0 5 18 11 33 4 3 92 1

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• reiserfsck on lvm

  - by DaDaDom

  It seems like my filesystem got corrupted somehow during the last reboot of my server. I can't fsck some logical volumes anymore. The setup: root@rescue ~ # cat /mnt/rescue/etc/fstab proc /proc proc defaults 0 0 /dev/md0 /boot ext3 defaults 0 2 /dev/md1 / ext3 defaults,errors=remount-ro 0 1 /dev/systemlvm/home /home reiserfs defaults 0 0 /dev/systemlvm/usr /usr reiserfs defaults 0 0 /dev/systemlvm/var /var reiserfs defaults 0 0 /dev/systemlvm/tmp /tmp reiserfs noexec,nosuid 0 2 /dev/sda5 none swap defaults,pri=1 0 0 /dev/sdb5 none swap defaults,pri=1 0 0 [UPDATE] First question: what "part" should I check for bad blocks? The logical volume, the underlying /dev/md or the /dev/sdx below that? Is doing what I am doing the right way to go? [/UPDATE] The errormessage when checking /dev/systemlvm/usr: root@rescue ~ # reiserfsck /dev/systemlvm/usr reiserfsck 3.6.19 (2003 www.namesys.com) [...] Will read-only check consistency of the filesystem on /dev/systemlvm/usr Will put log info to 'stdout' Do you want to run this program?[N/Yes] (note need to type Yes if you do):Yes ########### reiserfsck --check started at Wed Feb 3 07:10:55 2010 ########### Replaying journal.. Reiserfs journal '/dev/systemlvm/usr' in blocks [18..8211]: 0 transactions replayed Checking internal tree.. Bad root block 0. (--rebuild-tree did not complete) Aborted Well so far, let's try --rebuild-tree: root@rescue ~ # reiserfsck --rebuild-tree /dev/systemlvm/usr reiserfsck 3.6.19 (2003 www.namesys.com) [...] Will rebuild the filesystem (/dev/systemlvm/usr) tree Will put log info to 'stdout' Do you want to run this program?[N/Yes] (note need to type Yes if you do):Yes Replaying journal.. Reiserfs journal '/dev/systemlvm/usr' in blocks [18..8211]: 0 transactions replayed ########### reiserfsck --rebuild-tree started at Wed Feb 3 07:12:27 2010 ########### Pass 0: ####### Pass 0 ####### Loading on-disk bitmap .. ok, 269716 blocks marked used Skipping 8250 blocks (super block, journal, bitmaps) 261466 blocks will be read 0%....20%....40%....60%....80%....100% left 0, 11368 /sec 52919 directory entries were hashed with "r5" hash. "r5" hash is selected Flushing..finished Read blocks (but not data blocks) 261466 Leaves among those 13086 Objectids found 53697 Pass 1 (will try to insert 13086 leaves): ####### Pass 1 ####### Looking for allocable blocks .. finished 0% left 12675, 0 /sec The problem has occurred looks like a hardware problem (perhaps memory). Send us the bug report only if the second run dies at the same place with the same block number. mark_block_used: (39508) used already Aborted Bad. But let's do it again as mentioned: [...] Flushing..finished Read blocks (but not data blocks) 261466 Leaves among those 13085 Objectids found 54305 Pass 1 (will try to insert 13085 leaves): ####### Pass 1 ####### Looking for allocable blocks .. finished 0%... left 12127, 958 /sec The problem has occurred looks like a hardware problem (perhaps memory). Send us the bug report only if the second run dies at the same place with the same block number. build_the_tree: Nothing but leaves are expected. Block 196736 - internal Aborted Same happens every time, only the actual error message changes. Sometimes I get mark_block_used: (somenumber) used already, other times the block number changes. Seems like something is REALLY broken. Are there any chances I can somehow get the partitions to work again? It's a server to which I don't have physical access directly (hosted server). Thanks in advance!

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• Disable error_log. Error_log flooding

  - by user36646

  Hello, i got an webserver running and old version of gambio (xt:commerce fork). The error_log in the dir over the public_html is flooding with errors. About 30mb in 15min. How can I disable this log? I can't fix all the errors. Here are a few examples of the errors: [warn] mod_fcgid: stderr: PHP Notice: Undefined variable: key in /usr/www/users/foo//includes/classes/class.inputfilter.php on line 98 [warn] mod_fcgid: stderr: PHP Notice: Undefined index: in /usr/www/users/foo/templ [warn] mod_fcgid: stderr: in /usr/www/users/foo/templates/gambio/source/inc/xtc_show_category_sectionc.inc.php on line 47 They are all errors of: "mod_fcgid: stderr". I tried to grep "error_log" and "error_report" in the public html dir, but i did not find anything. Here is a part from the phpinfo(): PHP Version 4.4.9 System Linux foobar.com 2.6.26-2-686-bigmem #1 SMP Sat Dec 26 09:26:36 UTC 2009 i686 Build Date Feb 11 2010 13:00:33 Configure Command './configure' '--prefix=/usr/local/php4' '--with-config-file-path=/etc/php4/cgi' '--with-gd' '--with-jpeg-dir' '--with-png-dir' '--with-tiff-dir' '--with-ttf' '--enable-force-cgi-redirect' '--enable-safe-mode' '--with-zlib' '--enable-ftp' '--enable-url-includes' '--enable-gd-native-ttf' '--enable-trans-sid' '--enable-dbase' '--with-db4' '--with-ldap' '--enable-bcmath' '--enable-calendar' '--enable-memory-limit' '--with-mcal=/usr' '--with-bz2' '--with-mod-dav' '--enable-sockets' '--with-kerberos' '--with-imap-ssl' '--enable-gd-imgstrttf' '--with-freetype-dir' '--with-curl' '--with-mysql' '--with-mhash' '--with-gdbm' '--with-pgsql' '--with-gettext' '--with-xml' '--with-mcrypt' '--with-openssl' '--with-dom' '--without-pear' '--enable-exif' '--with-zip' '--enable-wddx' '--disable-cli' '--enable-fastcgi' '--with-imap' '--enable-xslt' '--with-xslt-sablot=/usr/local/lib' '--enable-mbstring' '--with-dom-xslt' '--with-dom-exslt' Server API CGI/FastCGI Virtual Directory Support disabled Configuration File (php.ini) Path /home/httpd/php-ini/foo/php.ini PHP API 20020918 PHP Extension 20020429 Zend Extension 20050606 Debug Build no Zend Memory Manager enabled Thread Safety disabled Registered PHP Streams php, http, ftp, https, ftps, compress.bzip2, compress.zlib **Configuration PHP Core** Directive Local Value Master Value allow_call_time_pass_reference On On allow_url_fopen Off Off always_populate_raw_post_data Off Off arg_separator.input & & arg_separator.output & & asp_tags Off Off auto_append_file no value no value auto_prepend_file no value no value browscap no value no value default_charset no value no value default_mimetype text/html text/html define_syslog_variables Off Off disable_classes no value no value disable_functions no value no value display_errors On On display_startup_errors Off Off doc_root no value no value docref_ext no value no value docref_root no value no value enable_dl On On error_append_string no value no value error_log no value no value error_prepend_string no value no value error_reporting 2039 2039 expose_php On On extension_dir /usr/local/php4/lib/php/extensions/no-debug-non-zts-20020429 /usr/local/php4/lib/php/extensions/no-debug-non-zts-20020429 file_uploads On On gpc_order GPC GPC highlight.bg #FFFFFF #FFFFFF highlight.comment #FF8000 #FF8000 highlight.default #0000BB #0000BB highlight.html #000000 #000000 highlight.keyword #007700 #007700 highlight.string #DD0000 #DD0000 html_errors On On ignore_repeated_errors Off Off ignore_repeated_source Off Off ignore_user_abort Off Off implicit_flush Off Off include_path .:/usr/local/lib/php/ .:/usr/local/lib/php/ log_errors Off Off log_errors_max_len 1024 1024 magic_quotes_gpc On On magic_quotes_runtime Off Off magic_quotes_sybase Off Off max_execution_time 120 120 max_input_nesting_level 500 500 max_input_time -1 -1 memory_limit 128000000 128000000 open_basedir /usr/www/users/foo:/usr/home/foo:/tmp:/usr/local/lib/php:/usr/local/rmagic:/usr/www/users/he/_system_ /usr/www/users/foo:/usr/home/foo:/tmp:/usr/local/lib/php:/usr/local/rmagic:/usr/www/users/he/_system_ output_buffering no value no value output_handler no value no value post_max_size 128000000 128000000 precision 14 14 register_argc_argv On On register_globals Off Off report_memleaks On On safe_mode Off Off safe_mode_exec_dir no value no value safe_mode_gid Off Off safe_mode_include_dir no value no value sendmail_from no value no value sendmail_path /usr/sbin/sendmail -t /usr/sbin/sendmail -t serialize_precision 100 100 short_open_tag On On SMTP localhost localhost smtp_port 25 25 sql.safe_mode Off Off track_errors Off Off unserialize_callback_func no value no value upload_max_filesize 128000000 128000000 upload_tmp_dir /usr/foo/foo/.tmp /usr/foo/.tmp user_dir no value no value variables_order EGPCS EGPCS xmlrpc_error_number 0 0 xmlrpc_errors Off Off y2k_compliance Off Off

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• BluRay audio/video stuttering with PowerDVD 11, WinDVD 11 Pro, etc? Xonar/Auzen HD audio option?

  - by jrista

  I recently upgraded my Windows 7 MediaCenter HTPC due to a motherboard failure (really old motherboard and cpu, it was on its last legs.) I chose to upgrade to an i5 system with everything built into the motherboard. I did my due diligence, researched, and found some hardware that was within my budget. I ended up with: Core i5 2500K (3.3Ghz) Corsair XMS3 2x2Gb DDR3 (4Gb) ASUS P8H 61-M LE/CSM MicroCenter 64Gb SSD (Previous BluRay player, forget the brand) The system is pretty awesome, and plays everything I have perfectly. I almost went with an Atom solution, however there have been numerous notes that they do not play NetFlix Instant Watch well...and I am a heavy Netflix IW user. High definition BluRay rips work well, although they usually contain lower audio quality than the BluRay's they were ripped from. The real problem I am encountering is playing back BluRay video from discs. For some reason, I am encountering rather terrible stuttering problems with both the audio and video. The stuttering is synchronous in both, and occurs at seemingly random intervals. I've used PowerDVD 9, PowerDVD 11 trial, and WinDVD 11 Pro trial. All three have stuttering problems, although PowerDVD 11 seems to have the least. Watching system resource usage, CPU load is never above 20%, and memory usage tends to be a constant 1/3rd the total available system memory. When playback is fine, its superb...the video is crystal clear. The audio quality is ok, certainly not what I would expect from a BluRay disc. I did some research, and it seems that playing BluRay from a PC causes a downsampling of the audio? I am curious if the audio is my primary problem here, the cause of the stuttering I am encountering? When stuttering occurs, the audio gets REALLY bad, while the video just pauses momentarily every second until for whatever reason everything picks up and runs fine (usually after a few seconds to a couple minutes.) The audio chipset is a Realtek HD ALC887 8-channel, supposedly designed to support BluRay playback. Has anyone encountered any issues like this playing back bluray discs on a PC (namely with PowerDVD...WinDVD was FAR worse, and seemed to have real trouble even reading the discs, and I have no interest in fiddling with it further.) Is there any reason to suspect the video decoding as the problem?(Given how bad the audio gets during a stutter, and how clean the video remains, I am inclined to think the issue boils down to audio.) Is it even remotely possible that the motherboard, cpu, or ram are causing the stuttering (all three are pretty blazing fast...faster than the hardware that I replaced, which seemed to play BluRay fine with PowerDVD 9.) I've read a bit about the Asus Xonar HDAV 1.3 and the Auzen X-Fi HomeTheater HD home theater hi-fi audio cards. Seems they are the only way to get true full-quality, uncompressed BluRay audio bitstreaming over HDMI on a PC. None of the usual suspects seem to have these cards in stock, however. Are these cards worth getting? Are they even still available, or have they been discontinued (if so, that would indeed be sad...they sound simply fantastic.)

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• ubuntu 10.04; kvm bridged networking not working with public ip addresses

  - by senorsmile

  I have a dedicated hosted server box with ubuntu 10.04 64 bit installed. I would like to run kvm with ubuntu 8.04 installed for some php 5.2 compatible apps(they don't work right with php 5.3, the default in ubuntu 10.04). I installed KVM as instructed at https://help.ubuntu.com/community/KVM/Installation . I installed the vm using virt-manager. I never could figure out how use virt-install or any of those automated installers. I just installed it using the disc. I set up bridged networking as per https://help.ubuntu.com/community/KVM/Networking . However, the bridged connection doesn't work. Here's my /etc/network/interfaces on the host, running ubuntu 10.04. (with specific public ip blanked) auto lo iface lo inet loopback auto eth0 iface eth0 inet manual auto br0 iface br0 inet static address xx.xx.xx.xx netmask 255.255.255.248 gateway xx.xx.xx.xa bridge_ports eth0 bridge_stp on bridge_fd 0 bridge_maxwait 10 ` Here's my /etc/network/interfaces on the guest, running ubuntu 8.04. auto lo iface lo inet loopback auto eth0 iface eth0 inet static address xx.xx.xx.xy netmask 255.255.255.248 gateway xx.xx.xx.xa The two vm's can communicate to each other. But, the guest vm can't access anyone in the real world. Here's my /etc/libvirt/qemu/store_804.xml <domain type='kvm'> <name>store_804</name> <uuid>27acfb75-4f90-a34c-9a0b-70a6927ae84c</uuid> <memory>2097152</memory> <currentMemory>2097152</currentMemory> <vcpu>2</vcpu> <os> <type arch='x86_64' machine='pc-0.12'>hvm</type> <boot dev='hd'/> </os> <features> <acpi/> <apic/> <pae/> </features> <clock offset='utc'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>restart</on_crash> <devices> <emulator>/usr/bin/kvm</emulator> <disk type='file' device='disk'> <driver name='qemu' type='raw'/> <source file='/var/lib/libvirt/images/store_804.img'/> <target dev='hda' bus='ide'/> </disk> <disk type='block' device='cdrom'> <driver name='qemu' type='raw'/> <target dev='hdc' bus='ide'/> <readonly/> </disk> <interface type='bridge'> <mac address='52:54:00:26:0b:c6'/> <source bridge='br0'/> <model type='virtio'/> </interface> <console type='pty'> <target port='0'/> </console> <console type='pty'> <target port='0'/> </console> <input type='mouse' bus='ps2'/> <graphics type='vnc' port='-1' autoport='yes'/> <sound model='es1370'/> <video> <model type='cirrus' vram='9216' heads='1'/> </video> </devices> </domain> Any idea where I've gone wrong?

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• Oracle Virtual Server OEL vm fails to start - kernel panic on cpu identify

  - by Towndrunk

  I am in the process of following a guide to setup various oracle vm templates, so far I have installed OVS 2. 2 and got the OVM Manager working, imported the template for OEL5U5 and created a vm from it.. the problem comes when starting that vm. The log in the OVMM console shows the following; Update VM Status - Running Configure CPU Cap Set CPU Cap: failed:<Exception: failed:<Exception: ['xm', 'sched-credit', '-d', '32_EM11g_OVM', '-c', '0'] => Error: Domain '32_EM11g_OVM' does not exist. StackTrace: File "/opt/ovs-agent-2.3/OVSXXenVMConfig.py", line 2531, in xen_set_cpu_cap run_cmd(args=['xm', File "/opt/ovs-agent-2.3/OVSCommons.py", line 92, in run_cmd raise Exception('%s => %s' % (args, err)) The xend.log shows; [2012-11-12 16:42:01 7581] DEBUG (DevController:139) Waiting for devices vtpm [2012-11-12 16:42:01 7581] INFO (XendDomain:1180) Domain 32_EM11g_OVM (3) unpaused. [2012-11-12 16:42:03 7581] WARNING (XendDomainInfo:1907) Domain has crashed: name=32_EM11g_OVM id=3. [2012-11-12 16:42:03 7581] ERROR (XendDomainInfo:2041) VM 32_EM11g_OVM restarting too fast (Elapsed time: 11.377262 seconds). Refusing to restart to avoid loops .> [2012-11-12 16:42:03 7581] DEBUG (XendDomainInfo:2757) XendDomainInfo.destroy: domid=3 [2012-11-12 16:42:12 7581] DEBUG (XendDomainInfo:2230) Destroying device model [2012-11-12 16:42:12 7581] INFO (image:553) 32_EM11g_OVM device model terminated I have set_on_crash="preserve" in the vm.cfg and have then run xm create -c to get the console screen while booting and this is the log of what happens.. Started domain 32_EM11g_OVM (id=4) Bootdata ok (command line is ro root=LABEL=/ ) Linux version 2.6.18-194.0.0.0.3.el5xen ([email protected]) (gcc version 4.1.2 20080704 (Red Hat 4.1.2-48)) #1 SMP Mon Mar 29 18:27:00 EDT 2010 BIOS-provided physical RAM map: Xen: 0000000000000000 - 0000000180800000 (usable)> No mptable found. Built 1 zonelists. Total pages: 1574912 Kernel command line: ro root=LABEL=/ Initializing CPU#0 PID hash table entries: 4096 (order: 12, 32768 bytes) Xen reported: 1600.008 MHz processor. Console: colour dummy device 80x25 Dentry cache hash table entries: 1048576 (order: 11, 8388608 bytes) Inode-cache hash table entries: 524288 (order: 10, 4194304 bytes) Software IO TLB disabled Memory: 6155256k/6299648k available (2514k kernel code, 135548k reserved, 1394k data, 184k init) Calibrating delay using timer specific routine.. 4006.42 BogoMIPS (lpj=8012858) Security Framework v1.0.0 initialized SELinux: Initializing. selinux_register_security: Registering secondary module capability Capability LSM initialized as secondary Mount-cache hash table entries: 256 CPU: L1 I Cache: 64K (64 bytes/line), D cache 16K (64 bytes/line) CPU: L2 Cache: 2048K (64 bytes/line) general protection fault: 0000 [1] SMP last sysfs file: CPU 0 Modules linked in: Pid: 0, comm: swapper Not tainted 2.6.18-194.0.0.0.3.el5xen #1 RIP: e030:[ffffffff80271280] [ffffffff80271280] identify_cpu+0x210/0x494 RSP: e02b:ffffffff80643f70 EFLAGS: 00010212 RAX: 0040401000810008 RBX: 0000000000000000 RCX: 00000000c001001f RDX: 0000000000404010 RSI: 0000000000000001 RDI: 0000000000000005 RBP: ffffffff8063e980 R08: 0000000000000025 R09: ffff8800019d1000 R10: 0000000000000026 R11: ffff88000102c400 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffffffff805d2000(0000) knlGS:0000000000000000 CS: e033 DS: 0000 ES: 0000 Process swapper (pid: 0, threadinfo ffffffff80642000, task ffffffff804f4b80) Stack: 0000000000000000 ffffffff802d09bb ffffffff804f4b80 0000000000000000 0000000021100800 0000000000000000 0000000000000000 ffffffff8064cb00 0000000000000000 0000000000000000 Call Trace: [ffffffff802d09bb] kmem_cache_zalloc+0x62/0x80 [ffffffff8064cb00] start_kernel+0x210/0x224 [ffffffff8064c1e5] _sinittext+0x1e5/0x1eb Code: 0f 30 b8 73 00 00 00 f0 0f ab 45 08 e9 f0 00 00 00 48 89 ef RIP [ffffffff80271280] identify_cpu+0x210/0x494 RSP ffffffff80643f70 0 Kernel panic - not syncing: Fatal exception clear as mud to me. are there any other logs that will help me? I have now deployed another vm from the same template and used the default vm settings rather than adding more memory etc - I get exactly the same error.

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• vlans on openvz, centos 6

  - by arheops

  i have centos 6 with openvz installed on it, switch with vlan support. I need following setup: 1) eth0 on openvz have be tagged multiple vlans. 2) each virtualhost have to be in single vlan. yes,i already read wiki on openvz, but it is just not work. I have on main server interface eth0.108 and able ping address on that interface(using nootbook on untagged port vlan 108), but i not able ping address inside container. Main node: [root@box1 conf]# ifconfig eth0 Link encap:Ethernet HWaddr D0:67:E5:F4:11:60 inet6 addr: fe80::d267:e5ff:fef4:1160/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:506 errors:0 dropped:0 overruns:0 frame:0 TX packets:25 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:68939 (67.3 KiB) TX bytes:1780 (1.7 KiB) Interrupt:16 Memory:c0000000-c0012800 eth0.108 Link encap:Ethernet HWaddr D0:67:E5:F4:11:60 inet addr:10.11.108.3 Bcast:10.11.111.255 Mask:255.255.252.0 inet6 addr: fe80::d267:e5ff:fef4:1160/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:238 errors:0 dropped:0 overruns:0 frame:0 TX packets:19 errors:0 dropped:12 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:25890 (25.2 KiB) TX bytes:926 (926.0 b) eth1 Link encap:Ethernet HWaddr D0:67:E5:F4:11:61 inet addr:192.168.23.233 Bcast:192.168.23.255 Mask:255.255.255.0 inet6 addr: fe80::d267:e5ff:fef4:1161/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:1967 errors:0 dropped:0 overruns:0 frame:0 TX packets:356 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:365298 (356.7 KiB) TX bytes:115007 (112.3 KiB) Interrupt:17 Memory:c2000000-c2012800 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:7 errors:0 dropped:0 overruns:0 frame:0 TX packets:7 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:784 (784.0 b) TX bytes:784 (784.0 b) venet0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet6 addr: fe80::1/128 Scope:Link UP BROADCAST POINTOPOINT RUNNING NOARP MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:3 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) veth108.0 Link encap:Ethernet HWaddr 00:18:51:DA:94:D5 inet6 addr: fe80::218:51ff:feda:94d5/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:639 errors:0 dropped:0 overruns:0 frame:0 TX packets:5 errors:0 dropped:1 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:17996 (17.5 KiB) TX bytes:308 (308.0 b) virtual node [root@pbx108 /]# ifconfig eth0.108 Link encap:Ethernet HWaddr 00:18:51:CA:B5:C5 inet addr:10.11.108.1 Bcast:10.11.111.255 Mask:255.255.252.0 inet6 addr: fe80::218:51ff:feca:b5c5/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5 errors:0 dropped:0 overruns:0 frame:0 TX packets:685 errors:0 dropped:2 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:308 (308.0 b) TX bytes:19284 (18.8 KiB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:683 errors:0 dropped:0 overruns:0 frame:0 TX packets:683 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:76288 (74.5 KiB) TX bytes:76288 (74.5 KiB) /etc/vz/conf/108.conf # RAM PHYSPAGES="0:4000M" # Swap SWAPPAGES="0:512M" # Disk quota parameters (in form of softlimit:hardlimit) DISKSPACE="200G:200G" DISKINODES="20000000:22000000" QUOTATIME="0" # CPU fair scheduler parameter CPUUNITS="4000" VE_ROOT="/vz/root/$VEID" VE_PRIVATE="/vz/private/$VEID" OSTEMPLATE="centos-6-x86_64" ORIGIN_SAMPLE="vswap-256m" NETIF="ifname=eth0.108,mac=00:18:51:CA:B5:C5,host_ifname=veth108.0,host_mac=00:18:51:DA:94:D5" NAMESERVER="8.8.8.8" HOSTNAME="pbx108.localhost" IP_ADDRESS=""

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• CPU Utilization LAMP stack

  - by Max

  We've got an ec2 m2.4xlarge running Magento (centos 5.6, httpd 2.2, php 5.2.17 with eaccelerator 0.9.5.3, mysql 5.1.52). Right now we're getting a large traffic spike, and our top looks like this: top - 09:41:29 up 31 days, 1:12, 1 user, load average: 120.01, 129.03, 113.23 Tasks: 1190 total, 18 running, 1172 sleeping, 0 stopped, 0 zombie Cpu(s): 97.3%us, 1.8%sy, 0.0%ni, 0.5%id, 0.0%wa, 0.0%hi, 0.0%si, 0.4%st Mem: 71687720k total, 36898928k used, 34788792k free, 49692k buffers Swap: 880737784k total, 0k used, 880737784k free, 1586524k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2433 mysql 15 0 23.6g 4.5g 7112 S 564.7 6.6 33607:34 mysqld 24046 apache 16 0 411m 65m 28m S 26.4 0.1 0:09.05 httpd 24360 apache 15 0 410m 60m 25m S 26.4 0.1 0:03.65 httpd 24993 apache 16 0 410m 57m 21m S 26.1 0.1 0:01.41 httpd 24838 apache 16 0 428m 74m 20m S 24.8 0.1 0:02.37 httpd 24359 apache 16 0 411m 62m 26m R 22.3 0.1 0:08.12 httpd 23850 apache 15 0 411m 64m 27m S 16.8 0.1 0:14.54 httpd 25229 apache 16 0 404m 46m 17m R 10.2 0.1 0:00.71 httpd 14594 apache 15 0 404m 63m 34m S 8.4 0.1 1:10.26 httpd 24955 apache 16 0 404m 50m 21m R 8.4 0.1 0:01.66 httpd 24313 apache 16 0 399m 46m 22m R 8.1 0.1 0:02.30 httpd 25119 apache 16 0 411m 59m 23m S 6.8 0.1 0:01.45 httpd Questions: Would giving msyqld more memory help it cache queries and react faster? If so, how? Other than splitting mysql and php to separate servers (which we're about to do) is there anything else we could/should be doing? Thanks! UPDATE: Here's our my.cnf along with the output of mysqltuner. It looks like a cache problem. Thanks again! # cat /etc/my.cnf [client] port = **** socket = /var/lib/mysql/mysql.sock [mysqld] datadir=/mnt/persistent/mysql port=**** socket=/var/lib/mysql/mysql.sock key_buffer = 512M max_allowed_packet = 64M table_cache = 1024 sort_buffer_size = 8M read_buffer_size = 4M read_rnd_buffer_size = 2M myisam_sort_buffer_size = 64M thread_cache_size = 128M tmp_table_size = 128M join_buffer_size = 1M query_cache_limit = 2M query_cache_size= 64M query_cache_type = 1 max_connections = 1000 thread_stack = 128K thread_concurrency = 48 log-bin=mysql-bin server-id = 1 wait_timeout = 300 innodb_data_home_dir = /mnt/persistent/mysql/ innodb_data_file_path = ibdata1:10M:autoextend innodb_buffer_pool_size = 20G innodb_additional_mem_pool_size = 20M innodb_log_file_size = 64M innodb_log_buffer_size = 8M innodb_flush_log_at_trx_commit = 1 innodb_lock_wait_timeout = 50 innodb_thread_concurrency = 48 ft_min_word_len=3 [myisamchk] ft_min_word_len=3 key_buffer = 128M sort_buffer_size = 128M read_buffer = 2M write_buffer = 2M # ./mysqltuner.pl >> MySQLTuner 1.2.0 - Major Hayden <[email protected]> >> Bug reports, feature requests, and downloads at http://mysqltuner.com/ >> Run with '--help' for additional options and output filtering -------- General Statistics -------------------------------------------------- [--] Skipped version check for MySQLTuner script [OK] Currently running supported MySQL version 5.1.52-log [OK] Operating on 64-bit architecture -------- Storage Engine Statistics ------------------------------------------- [--] Status: +Archive -BDB +Federated +InnoDB -ISAM -NDBCluster [--] Data in MyISAM tables: 2G (Tables: 26) [--] Data in InnoDB tables: 749M (Tables: 250) [!!] Total fragmented tables: 262 -------- Security Recommendations ------------------------------------------- -------- Performance Metrics ------------------------------------------------- [--] Up for: 31d 2h 30m 38s (680M q [253.371 qps], 2M conn, TX: 4825B, RX: 236B) [--] Reads / Writes: 89% / 11% [--] Total buffers: 20.6G global + 15.1M per thread (1000 max threads) [OK] Maximum possible memory usage: 35.4G (51% of installed RAM) [OK] Slow queries: 0% (35K/680M) [OK] Highest usage of available connections: 53% (537/1000) [OK] Key buffer size / total MyISAM indexes: 512.0M/457.2M [OK] Key buffer hit rate: 100.0% (9B cached / 264K reads) [OK] Query cache efficiency: 42.3% (260M cached / 615M selects) [!!] Query cache prunes per day: 4384652 [OK] Sorts requiring temporary tables: 0% (1K temp sorts / 38M sorts) [!!] Joins performed without indexes: 100404 [OK] Temporary tables created on disk: 17% (7M on disk / 45M total) [OK] Thread cache hit rate: 99% (537 created / 2M connections) [!!] Table cache hit rate: 0% (1K open / 946K opened) [OK] Open file limit used: 9% (453/5K) [OK] Table locks acquired immediately: 99% (758M immediate / 758M locks) [OK] InnoDB data size / buffer pool: 749.3M/20.0G -------- Recommendations ----------------------------------------------------- General recommendations: Run OPTIMIZE TABLE to defragment tables for better performance Enable the slow query log to troubleshoot bad queries Adjust your join queries to always utilize indexes Increase table_cache gradually to avoid file descriptor limits Variables to adjust: query_cache_size (> 64M) join_buffer_size (> 1.0M, or always use indexes with joins) table_cache (> 1024)

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• Dell Latitude E6430 Docking Station + Dual Monitor + Laptop Screen Tri-Monitor setup

  - by Larry

  I have a company issued laptop and docking station as well as two monitors The specifications of the hardware are as follows; Laptop: Latitude E6430 BIOS: A02.00 Processor: i7-3720QM CPU @ 2.60 (8 CPUs) Memory: 4096MB RAM Page file: 1825MB used, 4793MB available DirectX 11 Display Driver/Chip: MVIDIA NVS 5200M DAC: Integrated RAMDAC Aprox Total Memory: 2376 (Above 3 details same for both displays) Current Display Mode (Display 1): 1600x900 Current Display Mode (Display 2): 1440x900 the docking station is a Dell Latitude E6420 Docking Station PR03X Port Replicator and I don't think the monitor model is particularly relevant to resolving this issue but they are both Acer V193Ws The story goes like this; the laptop works fine if I VGA one monitor into the laptop through the vga port on the back of the lefthand side of the laptop I can achieve dual monitor display fine (laptop screen + monitor) if I plug the laptop into the docking station and use the vga port in the back of the docking station I can dual monitor fine (laptop screen + monitor) if I plug the laptop into the docking station, the laptop's lefthand side VGA port no longer seems to function at all I've spoken to internal IT about this issue and they're going to get me some kind of VGA splitter or a DVI-VGA adapter to use with the docking station for the second Acer Monitor, but that isn't going to happen for a few days. So I guess what I'm wondering is; is there any way to continue to use the side VGA port on my laptop while using the docking station VGA port? and as a secondary 'followup' pending resolution of the initial issue with getting both monitors up and running (at the moment I have both monitors on my desk but am just using my laptop screen as one of my dual monitor display with one of the monitors [the one connected to dock]), is there any way to CONTINUE to use my laptop monitor to in effect have a triple monitor display (2 monitors + docked laptop)? I am wondering this because internal IT told me that they were aware of some issues with the particular display drivers in my box and triple monitor displays but weren't really going to look TOO much in-depth into that (which is perfectly understandable) since getting the adapter for the dual monitors up and running was the greater priority within their purview. So this is a two parter; Can I dual monitor using two vga cables with 1 docking station vga port and one laptop vga port? is there a setting that can be tweaked somewhere? because plugging the box into the station seems to make the side port stop working and... Is there any reasonably simple and cost-effective work around (e.g. I am find with shelling out maybe a few dollars out of my own pocket for some hardware or software to make my company box tri-display capable) but if this requires some extensive rebuild or new OSs or doing stuff to the BIOS I'd rather have a straight answer about this being untenable as a slight modification to a (once again) company laptop and stop wasting time looking into it Thanks! and please let me know if you guys need any more details (tech specs or something) to answer this question [EDIT] 2/10/2014 Just an update; turned out it really was just a hardware limitation issue. The old laptop just couldn't hack it. Got a new laptop with a better video card and different monitors from my company and am successfully using a triple display currently (2 monitors + laptop screen)

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