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How to find out what is causing a slow down of the application on this server?

- by Jan P.

This is not the typical serverfault question, but I'm out of ideas and don't know where else to go. If there are better places to ask this, just point me there in the comments. Thanks. Situation We have this web application that uses Zend Framework, so runs in PHP on an Apache web server. We use MySQL for data storage and memcached for object caching. The application has a very unique usage and load pattern. It is a mobile web application where every full hour a cronjob looks through the database for users that have some information waiting or action to do and sends this information to a (external) notification server, that pushes these notifications to them. After the users get these notifications, the go to the app and use it, mostly for a very short time. An hour later, same thing happens. Problem In the last few weeks usage of the application really started to grow. In the last few days we encountered very high load and doubling of application response times during and after the sending of these notifications (so basically every hour). The server doesn't crash or stop responding to requests, it just gets slower and slower and often takes 20 minutes to recover - until the same thing starts again at the full hour. We have extensive monitoring in place (New Relic, collectd) but I can't figure out what's wrong; I can't find the bottlekneck. That's where you come in: Can you help me figure out what's wrong and maybe how to fix it? Additional information The server is a 16 core Intel Xeon (8 cores with hyperthreading, I think) and 12GB RAM running Ubuntu 10.04 (Linux 3.2.4-20120307 x86_64). Apache is 2.2.x and PHP is Version 5.3.2-1ubuntu4.11. If any configuration information would help analyze the problem, just comment and I will add it. Graphs info phpinfo() apc status memcache status collectd Processes CPU Apache Load MySQL Vmem Disk New Relic Application performance Server overview Processes Network Disks (Sorry the graphs are gifs and not the same time period, but I think the most important info is in there)

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EventID 1058 Code 5, Sysvol is subdir of Sysvol - how to fix?

- by nulliusinverba

I have been trying to resolve this error, like many others: The processing of Group Policy failed. Windows attempted to read the file \domain.local\SysVol\domain.local\Policies{3EF90CE1-6908-44EC-A750-F0BA70548600}\gpt.ini from a domain controller and was not successful. Group Policy settings may not be applied until this event is resolved. This issue may be transient and could be caused by one or more of the following: a) Name Resolution/Network Connectivity to the current domain controller. b) File Replication Service Latency (a file created on another domain controller has not replicated to the current domain controller). c) The Distributed File System (DFS) client has been disabled. Error code: 5 = Access Denied. The incredibly helpful post is this one (http://www.experts-exchange.com/OS/Microsoft_Operating_Systems/Server/2003_Server/A_1073-Diagnosing-and-repairing-Events-1030-and-1058.html). Quoting from this post: HERE IS A LIST OF POTENTIAL PROBLEMS THAT CAN LEAD TO 1030 AND 1058 EVENT ERRORS: --Sometimes the permissions of the file folders that contain Group policies (the Sysvol folder) can be corrupted. --Sometimes you have problems with NetBIOS: --Sometimes the GPO itself is corrupt, or you have a partial set of data for that GPO. --Sometimes you may have problems with File Replication Services, which almost always indicates a problem with DNS --Sysvol may be a subfolder of itself: Sysvol/Sysvol I have the problem listed where sysvol is a subfolder of sysvol. The directory structure is: -sysvol -domain -staging -staging areas -sysvol (shared as "\\server\sysvol") -domain.local -ClientAgent -Policies -scripts Interestingly, the second sysvol folder is the one that is shared as "\server\sysvol". This makes me confident this is the issue with the permissions and error code 5. Also interestingly, my server 2008 R2 servers can see it fine - my server 2008 servers cannot, and get the error. This is consistent across all my servers. This latter fact makes me uncertain what I need to do to fix this up. Do I, e.g., simply move the shared sysvol folder up a level to replace the non-shared one? Any help greatly appreciated. Cheers, Tim.

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Hard drive degredation from large memory usage and paging files?

- by Stephen R

I've had a question(s) regarding computer degradation going through my head for a while and haven't found many good resources for researching it. 1) First off, when is the virtual RAM/paging file on a hard drive used by Windows? Is it used when the RAM is full? Or does it use the Virtual RAM/paging file as intermediate caching between the RAM and actual hard drive space all the time? 2) If I were to run many applications on my computer at the same time and have a bad habit of doing this for the entire lifetime of the computer, does it use more of the virtual RAM/paging file than if I were to have fewer programs running? Just to note, the RAM never fills up on my computer but it is used heavily. 3) By extension of question 2, if the virtual RAM/paging file is used more heavily, would that result in rapid hard drive degradation? I have seen a pattern among all of the computers that I have owned or used in the past 5 years. I am the kind of person to leave my web browser up with 40 tabs among other programs which will eat up 40% of my memory typically. Over time my computer will slow down, browsers start crashing, programs start seizing up or crashing themselves, eventually the computer becomes essentially unusable. I have been trying to rack my mind to come up with a solution other than to purchase a new PC to have it die on me in the next couple years as well. This is the only thought that has come to mind that might have a simple hardware fix...Windows ReadyBoost...Maybe? I'd like to be able to discuss this so I can learn something about all of the above. Thanks.

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Why is dwm.exe using so much memory?

- by Leonard Challis

I've scoured the web, but I'm sick of reading "scan your computer for viruses" and "upgrade your RAM" on answers to similar questions to this. I understand that dwm.exe is for (simply put) caching bitmaps for things like Aero-peek and similar, but as far as I have read it shouldn't be using vast amounts of memory. My colleague and I both have 4GB of RAM, Core 2 Duo, blah, blah -- essentially they're pretty capable. His dwm.exe is running at around 30mb, mind is currently running at about half a gig, though it does fluctuate quite a lot. This is the same while running the exact same applications (currently Zend studio, FireFox (with firemin - low memory usage), Outlook). Every so often I will get a notification asking me if I want to switch to Aero Basic because it's using too much memory, and sometimes it will just switch itself to basic and let me know why. I know it's possible to stop it switching, but I want to know why it is using too much memory otherwise it's just papering over the cracks. One thing to add is this seems to have started after a robbery on Monday, where two of my monitors were stolen, and I had to temporarily use a couple of alternative monitors. I am now using brand new monitors but the problem is the same. All drivers installed and working seemingly fine. Any ideas why the usage is so high? We are using windows 7 64-bit Professional.

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Redirecting a single request to another pages, ignoring www subdomain

- by Petter Brodin

I have a site running on IIS 7.5 that does an automatic redirect from 'http://mysite.com/whatever.aspx' to 'http://www.mysite.com/whatever.aspx' On the site, there is a lot of traffic to an old URL that I want to redirect to the front page, index.aspx: 'http://mysite.com/foo/bar/index.cgi%something=asdf&somethingelse=qwerty' The problem is that no matter what I try, I can only get the redirect to work with the www subdomain. If I use the URL without www, I just end up at 'http://www.mysite.com/404.aspx' Any ideas? Thanks in advance for all help! Edit3: it seems like the browser caching the redirect response was messing with me, so edit2 is wrong. See my response below. Edit2: disregard edit1, it doesn't seem like it's working after all. Edit: here's some further info: using this article I've managed to redirect from 'http://mysite.com/foo/bar/index.cgi' to 'http://www.mysite.com/index.aspx', but if I add the query string parameters, it still redirects to 'http://www.mysite.com/404.aspx' Isn't there a way to catch all requests to the cgi file, including query string parameters?

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Why is writing to my external hard drive slow, while benchmarks show fast writing?

- by matix2267

I have an iOmega eGo 320GB portable drive connected through USB2.0 to my laptop running Windows Vista. It's been working fine for quite some time until recently it became very slow when writing e.g. when copying ~300MB movie over to the drive at first it is extremely fast but it actually doesn't write it only puts in cache and then hangs on last 10-20MBs for about a minute. When copying larger files it's the same story: starts fast but then slows down to ~5MB/s (sometimes even slower down to 2MB/s). Strange thing is that I have always had caching disabled for this drive (it was disabled by default and I never bothered changing it). At first I thought that the disk is dying so I checked S.M.A.R.T. values and everything is fine there. I also run chkdsk and it seemed to fix the problem - it worked fast for a few minutes but then it slowed down again. I also tried plugging it into another USB port - no difference. Additionally I noticed that reading under certain circumstances is sometimes slower e.g. loading times for some games are ~10 times longer, whereas simple copying files from this drive to my internal HDD is fast. I ran a speed benchmark using CrystalDiskMark with a 5x100MB run and strangely got these results: read write (MB/s) Seq 33.05 28.25 512k 17.30 15.27 4k 0.267 0.372 4kQD32 0.510 0.260 This is different from what most other people have (I've found many threads about slow disk write while googling but all of them were slow on benchmarks too) which is why I decided to post this problem here. BTW most of the time when writing (or sometimes reading) the activity led is mostly idle (blinks a while and then stops for longer, sometimes has slower blinks ~1 sek, sometimes goes off for a few seconds - extremely long blink :) ) but when benchmarking, defragmenting or just reading (copying from this drive, installing apps from installers there, watching HD videos) it is blinking really fast (like it should) and there are no slowdowns. It shouldn't be driver issue unless stock Windows drivers have some issues I'm not aware of.

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VirtualBox management interface unreliability

- by Arlen Cuss

I'm using VirtualBox 3.2.8_OSE with 20 VMs running, and everything's going fine. I find that if I hammer the VBoxManage interface, all sorts of interesting things happen, usually necessitating either a restart of the VM in question, or of all VMs. For instance, if I use VBoxManage guestcontrol execute to run processes, after a few hours of using it maybe once or twice a minute on any given VM, it'll mysteriously start reporting VERR_NOT_IMPLEMENTED and refusing to do anything—sometimes trying to restart /usr/sbin/VBoxService on the VM itself will get it back in working order, but often it won't, and in the meantime, no data can be collected using VBoxManage. Such data includes the VM's IP, so if I hadn't recorded it earlier, I'm usually in trouble and have no option but to portscan the network for it, or kill the VM's process on the host manually and restart it. This one I haven't narrowed down yet, but it seems that even using VBoxManage guestproperty get (to retrieve a machine's IP) frequently and rapidly is enough to cause all VMs' management interfaces to die. The processes are still running fine, but VBoxManage reports them all as "powered off". In the meantime, another process somewhere in the system seems to have decided that their being powered off means they need to be powered on again, and suddenly I have 2x the number of VBoxHeadless processes running than I used to. Has anyone else seen behaviour like this? Is there any workaround? This is a serious impediment to my work, as I've had to resort to a lot of (hacky) caching of data and rate-limiting how often I call VBoxManage, just in case I accidentally bring 20 VMs to their knees.

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Autounmounting USB keys with FAT filesystem on Linux (RHEL5)

- by niXar

For security reasons, I have two workstations i front of me, and I can only transfer data between them through a USB key. As you can imagine, it can get quickly tiresome, but the most annoying is having to unmount the things before removing them. Not umounting them results in missing files most of the time, even if I remove them a while after having last written to them. Now, since they're only used for transferring smallish files, and each are basically written once and read once, I don't need the fancy pansy caching infrastructure that makes clean unmounting a necessary step. And since the data is always a copy of something I have at hand, I don't care if the filesystem croaks from time to time. But anyway the system doesn't need to force that on me, it could simply make sure everything is committed with a second, and works synchronously. Then when I remove the key, nothing is lost. Is there a way to do this? I would appreciate any other tips on handling this situation. Edit: it appears the situation has changed between RHEL5 and Fedora up to F11 on one hand, and F12 on the other. The latter use DeviceKit-disk, and I haven't quite figured out how to do this. The method provided below in gconf does not work anymore.

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ipv6 reverse DNS delegation

- by user1709492

I currently have 2001:1973:2303::/48 assigned to me and i'll be assigning /64's to customer's I'd like to have 1 zonefile for the /48 where i can essentially point / redirect query to different nameservers. Example ( Desired effect ) 2001:1973:2303:1234::/64 -> ns1.example.com, ns2.example.com 2001:1973:2303:2345::/64 -> ns99.example2.com, ns100.example2.com 2001:1973:2303:4321::/64 -> ns1.cust1.com, ns2.cust1.com Current /48 zonefile $TTL 3h $ORIGIN 3.0.3.2.3.7.9.1.1.0.0.2.ip6.arpa. @ IN SOA ns3.example.ca. ns4.example.ca. ( 2011071030 ; serial 3h ; refresh after 3 hours 1h ; retry after 1 hour 1w ; expire after 1 week 1h ) ; negative caching TTL of 1 hour IN NS ns3.example.ca. IN NS ns4.example.ca. 1234 IN NS ns1.example.com. NS ns2.example.com. 2345 IN NS ns99.example2.com. NS ns100.example2.com. 4321 IN NS ns1.cust1.com. NS ns2.cust1.com. Where am i going wrong ? My request seems simple to me atleast. To put it in terms of firewalling i want to redirect traffic client queries 2001:1973:2303:4321::1 - ns3.example.ca sees the request and redirects the query to ns1.cust1.com - ns1.cust1.com answers the query with omg.itworks.ca ( provided ns1.cust1.com is properly configured.

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Shared Files stuck locked even after closing all sessions

- by Chris S

We run a business app from a shared network drive (has to be this way). When I go to do updates it complains that files are locked. Generally there are open sessions from people who left their computer on, but with no locks on files; there aren't necessarily always sessions open when it complains about locked files. If I close these sessions they disappear. I say "disappear" because I suspect they're actually hanging open. If I try to restart the Server service, it hangs on stopping. Restarting the whole server (it's a VM) unlocks the files. The Server is a Windows 2008 R2 Ent VM running on Hyper-V; the share is accessed through DFS. Offline Files and caching are disabled (Share and GPO). All clients are Win7. Nothing has SP1 yet. Any ideas on what causes the file locks to hang? Any ideas for a solution other than rebooting the server every time?

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JBoss https on port other than 8080 not working

- by MilindaD

We have a server with two JBoss instances where one runs on 8080, the other on 8081. We need to have HTTPS enabled for the 8081 server, firstly we tried enabling https on the 8080 port instance by generating the keystore and editing the server.xml and it successfully worked. However when we tried the same thing for 8081 it did not, note that we removed https for the 8080 server first before enabling it for 8081. This is what was used for both server.xml for 8080 and 8081. The only difference was that the port was changed from 8080 to 8081 when trying to enable https for 8081 port instance. What am I doing wrong and what needs to be changed? NOTE : When I meant enabled for 8080 I meant when you visit https:// URL:8484 you will actually be visiting the 8080 port instance. However when ssl is enabled for 8081 and I visit https:// URL:8484 I get that the web page is unavailable. COMMENTLESS VERSION <Server> <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" /> <Listener className="org.apache.catalina.core.JasperListener" /> <Service name="jboss.web">  <Connector port="8080" address="${jboss.bind.address}" maxThreads="350" maxHttpHeaderSize="8192" emptySessionPath="true" protocol="HTTP/1.1" enableLookups="false" redirectPort="8443" acceptCount="100" connectionTimeout="20000" disableUploadTimeout="true" compression="on" ompressableMimeType="text/html,text/css,text/javascript,application/json,text/xml,text/plain,application/x-javascript,application/javascript"/> <Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true" maxThreads="150" scheme="https" secure="true" clientAuth="false" sslProtocol="TLS" address="${jboss.bind.address}" keystoreFile="${jboss.server.home.dir}/conf/supun1.keystore" keystorePass="aaaaaa" truststoreFile="${jboss.server.home.dir}/conf/supun1.keystore" truststorePass="aaaaaa" />  <Connector port="8009" address="${jboss.bind.address}" protocol="AJP/1.3" emptySessionPath="true" enableLookups="false" redirectPort="8443" /> <Engine name="jboss.web" defaultHost="localhost" jvmRoute="khms1"> <Realm className="org.jboss.web.tomcat.security.JBossSecurityMgrRealm" certificatePrincipal="org.jboss.security.auth.certs.SubjectDNMapping" allRolesMode="authOnly" /> <Host name="localhost" autoDeploy="false" deployOnStartup="false" deployXML="false" configClass="org.jboss.web.tomcat.security.config.JBossContextConfig" > <Valve className="org.jboss.web.tomcat.service.sso.ClusteredSingleSignOn" /> <Valve className="org.jboss.web.tomcat.service.jca.CachedConnectionValve" cachedConnectionManagerObjectName="jboss.jca:service=CachedConnectionManager" transactionManagerObjectName="jboss:service=TransactionManager" /> </Host> </Engine> </Service> </Server> WITH COMMENTS VERSION <Server>  <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />  <Listener className="org.apache.catalina.core.JasperListener" />  <Service name="jboss.web">  <Connector port="8080" address="${jboss.bind.address}" maxThreads="350" maxHttpHeaderSize="8192" emptySessionPath="true" protocol="HTTP/1.1" enableLookups="false" redirectPort="8443" acceptCount="100" connectionTimeout="20000" disableUploadTimeout="true" compression="on" ompressableMimeType="text/html,text/css,text/javascript,application/json,text/xml,text/plain,application/x-javascript,application/javascript"/>   <Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true" maxThreads="150" scheme="https" secure="true" clientAuth="false" sslProtocol="TLS" address="${jboss.bind.address}" keystoreFile="${jboss.server.home.dir}/conf/supun1.keystore" keystorePass="aaaaaa" truststoreFile="${jboss.server.home.dir}/conf/supun1.keystore" truststorePass="aaaaaa" />  <Connector port="8009" address="${jboss.bind.address}" protocol="AJP/1.3" emptySessionPath="true" enableLookups="false" redirectPort="8443" /> <Engine name="jboss.web" defaultHost="localhost" jvmRoute="khms1">  <Realm className="org.jboss.web.tomcat.security.JBossSecurityMgrRealm" certificatePrincipal="org.jboss.security.auth.certs.SubjectDNMapping" allRolesMode="authOnly" />  <Host name="localhost" autoDeploy="false" deployOnStartup="false" deployXML="false" configClass="org.jboss.web.tomcat.security.config.JBossContextConfig" >        <Valve className="org.jboss.web.tomcat.service.sso.ClusteredSingleSignOn" />  <Valve className="org.jboss.web.tomcat.service.jca.CachedConnectionValve" cachedConnectionManagerObjectName="jboss.jca:service=CachedConnectionManager" transactionManagerObjectName="jboss:service=TransactionManager" /> </Host> </Engine> </Service> </Server>

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Multiple servers vs 1 big server performace

- by pistacchio

Hi to all! My team of developers has suggested a server structure for an upcoming project we are developing. Our structure is "logical", meaning that the various logical components of the application (it is a distributed one) relies on different servers. Some components are more critical than others and will be subjected to more load. Our proposal was to have 1 server per component but the hardware guys suggested to replace the various machines with a single, bigger one with virtual servers. They're gonna use Blade Servers. Now, I'm not an expert at all, but my question to the guys was: so if we need, for example, 3 2GHz CPU / 2GB RAM machines and you give me 1 machine with 3 2GHz CPUs and 6 GB of RAM it is the same? They told me it is. Is this accurate? What are the advantages or disadvantages of both the solutions? What are the generally accepted best practices? Could you point out some URL reference dealing with the problem? Thank you in advance! EDIT: Some more info. The (internet / intranet) application is already layered. We have some servers on the DMZ that will expose pages to the internet and the databases are on their own machines. What we want to split (and they want to join) are some webservers that mainly expose webservices. One is a DAL that communicates with the database layer, one is our Single Sign On / User Profile application that gets called once per page and one is a clone of what seen on the Internet to be used on our lan.

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Synchronize two directories on linux pc

- by Gab

I need a distributed filesystem (or a synchronization tool) that is capable of keeping a directory synchronized across 4 pc. My requirements are: offline access (data must be available offline on each pc) preserve execution rights: some files are marked executable on a linux partition. This flag should be replicated. efficient sync strategy: some of my files are 20GB, they are changed quite often, but in very little parts (Virtualbox images). Delta transmissions are welcome. efficient handling of space: no history for files, files shouldn't be copied to temp directories "just in case you break it". it must propagate deletions of files modification can happen in any of the 4 pcs, they should be propagated when other pc are connected. Other specs of my solution are: Sync is over a lan, the total amount of data to be synced is around 180GB, in some ten thousand files. Changes are small, but can happen in big files. At the moment i'm interested in a linux only solution. conflicts either don't happen or are solved with "last one wins" I haven't found any good solution. I've been trying: unison: it is the only one working at the moment, but during the hashing phase it hangs my pc for some minute, disk light steady on. Sparkleshare doesn't handle large files nicely. It keeps an history of all your changes that grows up indefinitely. They promise it will be fixed in next releases, but at the moment it still doesn't fit my needs. owncloud (keeps history of each file i change) coda ? (help! i couldn't set it up correctly!) git-annex assistant transforms all your files in symlinks and mark the original file as read only ("just in case you make a mistake while you modify it"!). Before you edit a file you have to issue a special command "git-annex unlock", that creates a local copy of the file, and you have to remember to lock it again if you want it synchronized. What to try next?

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What's throttling the database?

- by Troels Arvin

Hardware: Intel x86_64 with 192GB of RAM. OS: CentOS 5.4 x86_64. DBMS: DB2 v. 9.7.1 64 bit. During certain special workloads (e.g. parallel REORGs/RUNSTATs), I've seen the server transporting 450MB/s with 25000IO/s (yes, there is probably some storage system caching happening here) while all CPU cores were happily working in an even mix of usermode/wait. And disk benchmark tools can also bring some very satisfying bandwith and IO/s numbers to the table. On the other hand, we also have another scenario: A single rather complex query with at least one large table scan. db2's "list applications" reports that the query is Executing (not locked). IO: At most 10MB/s, 500 IO/s; CPU: two cores in 99.9% wait state, all other cores 100% idle. The tables which the query reads from have been altered to have LOCKSIZE=TABLE, so I would think that lock list work is zero. What's going on in such a situation? What tools/snapshots/... can I use to gain better insight in such a case?

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Extract sender activity from postfix logs for auditing user

- by Aseques

We have a mail user on our postfix server that was using the company mail to send compromising information to the competence. I've been asked to make a report of the actions for that user in the last time. There are tools like pflogsumm and others that can extract statistic data, but I haven't so far find anything useful to get all the info for a user because the data is in multiple lines. I'd like to get something like this: For the sent mail 11/11/11 00:00:00 [email protected] -> [email protected] 11/11/11 00:00:01 [email protected] -> [email protected] For the received mail 10/10/11 00:00:00 [email protected] -> [email protected] 10/10/11 00:00:01 [email protected] -> [email protected] I know I can do a script by myself, but matching the postfix ID for every mail is not something that can be made with a simple grep, and I've a lot of mail history that I have to recheck distributed among diferent files and so on. The source log is the standard postfix format, for example this one... Sep 13 16:15:57 server postfix/qmgr[18142]: B35CB5ED3D: from=<[email protected], size=10755, nrcpt=1 (queue active) Sep 13 16:15:57 server postfix/smtpd[32099]: disconnect from localhost[127.0.0.1] Sep 13 16:15:57 server postfix/smtp[32420]: 58C3E5EC9C: to=<[email protected]>, relay=127.0.0.1[127.0.0.1]:10024, delay=1.4, delays=0.01/0/0/1.4, dsn=2.0.0, status=sent (250 2.0.0 Ok, id=32697-04, from MTA([127.0.0.1]:10025): 250 2.0.0 Ok: queued as B35CB5ED3D) Sep 13 16:15:57 server postfix/qmgr[18142]: 58C3E5EC9C: removed Sep 13 16:15:57 server postfix/smtp[32379]: B35CB5ED3D: to=<[email protected]>, relay=mail.anothercompany.com[123.123.123.163]:25, delay=0.06, delays=0.03/0/0.01/0.02, dsn=2.0.0, status=sent (250 2.0.0 Ok: queued as 77D0EB6C025) Sep 13 16:15:57 server postfix/qmgr[18142]: B35CB5ED3D: removed

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Server 2003 and SSL Certificates

- by Keith Stokes

I have a Windows 2000 domain with dozens of Windows 2000 servers and a few 2003 servers. Each server runs a custom app talking to a 3rd party utilizing self-signed certificates. To help troubleshooting we've created a custom test app. The 2000 servers are able to talk within seconds. The 2003 servers take anywhere from 10-30 seconds using a domain account and much less, usually under 5 seconds using a local account. The only exception to the local account performance is a new account, which is slow initially then faster. If you leave the test app open and reconnect repeatedly it talks in seconds. If you leave it open for sometime between 1 and 2 hours, it reverts back to the previous 10 seconds, so obviously something is caching. Installing the destination certificates in the local 2003 server store makes no difference. I've installed the certificates in AD and that apparently makes domain accounts work in 9-12 seconds, vs 30 seconds that was regular before. Manually clearing the certificate store on the 2003 server makes no difference. I'm at a loss as to where the certs might be cached and if I'm using some sort of domain certificate store that's hiding from me.

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How can I use wildcards in an Nginx map directive?

- by Ian Clelland

I am trying to use Nginx to served cached files produced by a web application, and have spotted a potential problem; that the url-space is wide, and will exceed the Ext3 limit of 32000 subdirectories. I would like to break up the subdirectories, making, say, a two-level filesystem cache. So, where I am currently caching a file at /var/cache/www/arbitrary_directory_name/index.html I would store that instead at something like /var/cache/www/a/r/arbitrary_directory_name/index.html My trouble is that I can't get try_files, or even rewrite to make that mapping. My searching on the subject leads me to believe that I need to do something like this (heavily abbreviated): http { map $request_uri $prefix { /aa* a/a; /ab* a/b; /ac* a/c; ... /zz* z/z; } location / { try_files /var/cache/www/$prefix/$request_uri/index.html @fallback; # or # if (-f /var/cache/www/$prefix/$request_uri/index.html) { # rewrite ^(.*)$ /var/cache/www/$prefix/$1/index.html; # } } } But I can't get the /aa* pattern to match the incoming uri. Without the *, it will match an exact uri, but I can't get it to match just the first two characters. The Nginx documentation suggests that wildcards should be allowed, but I can't see a way to get them to work. Is there a way to do this? Am I missing something simple? Or am I going about this the wrong way?

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Windows 7 caches FTP credentials?

- by Martin Booka Weser

On my remote maschine i have an iis 7.5 (win server 2008) and set up an ftp site with iis manager authentication. I then did active directory user isolation and isolated my users to physical folders according to their names. So far, so good. I can access with ftp cliens from everywhere with different test accounts that i previously set up in the iis manager auth. Every user connects to its own folder. When i now tested with windows 7 as a client i did the following. Explorer - computer - right click - add network address - the ip of my remote maschine - user1 - password1 Perfect - it works. I now want to connect with user2. So I deleted this network address and set up a new connection, but with user2 (or even anonymous) instead. Now the strange thing: Windows doesn't even ask me for a password again. It just connects me to the folder of the user1. I already disabled ftp caching in the IIS and i disabled the user1 account in IIS manager authentication! Still, if i set up a network connection with this windows 7 it connects to the folder user1 . No matter which username i use (anonymous, administrator, user2,...). And if i connect with other ftp clients or other computers it all works perfectly. So I assume that this one windows somehow caches the credentials... But then, why does the IIS still accepts this credentials even if i disabled this user1 account??? Thanks.

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CloudFront with Custom Origin and ELB

- by kmfk

We are using CloudFront for our static assets but also wanted to allow for Gzip. We set up a new distribution with a custom origin pointing back to our application servers which are behind a elastic load balancer. We manually keep the files in sync across the cluster and update them when we publish. However, with this set up, we get nothing but Miss and RefreshHits from CloudFront, which so far has defeated the purpose. Is there any additional settings in order to use an ELB as your custom origin? In the docs, it references this as a viable solution. It appears when we point the distribution to a single server in our production cluster, cloudfront properly caches our assets. Is it possible that the sticky sessions cookie and the subsequent header that gets added by it could be an issue? Cache-Control: no-cache="set-cookie" //Added by load balancer Any ideas? FYI - currently, we have our custom origin pointing to a single EC2 instance, so caching is working correctly - in case you try to curl the file below. Example headers: curl -I http://static.quick-cdn.com/css/9850999.css HTTP/1.0 200 OK Accept-Ranges: bytes Cache-Control: max-age=3700 Cache-Control: no-cache="set-cookie" Content-Length: 23038 Content-Type: text/css Date: Thu, 12 Apr 2012 23:03:52 GMT Last-Modified: Thu, 12 Apr 2012 23:00:14 GMT Server: Apache/2.2.17 (Ubuntu) Vary: Accept-Encoding X-Cache: RefreshHit from cloudfront X-Amz-Cf-Id: K_q7Zy3_jdzlEJ85ukELVtdx1GmuXqApAbZZ7G0fPt0mxRMqPKX5pQ==,RzJmPku-rEIO9WlvuSoKa8hiAaR3dLk5KC4cQMWWrf_MDhmjWe8n6A== Via: 1.0 28c34f9fbf559a21ee16594849e4fc9c.cloudfront.net (CloudFront) Connection: close

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Migrating JBoss installation and install it on a PHP server

- by David Martinez

I'm configuring a new dedicated server that is going to run 3 sites, 2 of then are migrating from a old server. Each site have it's own domain and dedicated ip. 2 of this sites are already up and running on php (one of then use cakePHP), the third site is a migration from an old server and it runs on JBoss. 1) Is it possible to have both Jboss and php running on the same Apache instance, or would I have to install a new one? 2) Can I just move the old JBoss server directory to the new server and start the server with the shell script? From what I red here JBoss is distributed as a zip/tgz file with the server structure, so moving it from the old server to the new one should be the same. I want to do this because the old server is already configured, and it have 2 JBoss instances. I didn't develop this site and I don't have experience with JBoss. I have some documentation of the site, but it is not much, mostly server structure and the technology they used. The new server runs on CentOS with CPanel, I have full root access to the server. This question is similar to this one How can I run JBoss Application Server and Apache on the same server? but there he didn't have a dedicated IP for each domain.

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Large, high performance object or key/value store for HTTP serving on Linux

- by Tommy

I have a service that serves images to end users at a very high rate using plain HTTP. The images vary between 4 and 64kbytes, and there are 1.300.000.000 of them in total. The dataset is about 30TiB in size and changes (new objects, updates, deletes) make out less than 1% of the requests. The number of requests pr. second vary from 240 to 9000 and is dispersed pretty much all over, with few objects being especially "hot". As of now, these images are files on a ext3 filesystem distributed read only across a large amount of mid range servers. This poses several problems: Using a fileysystem is very inefficient since the metadata size is large, the inode/dentry cache is volatile on linux and some daemons tend to stat()/readdir() it's way through the directory structure, which in my case becomes very expensive. Updating the dataset is very time consuming and requires remounting between set A and B. The only reasonable handling is operating on the block device for backup, copying, etc. What I would like is a deamon that: speaks HTTP (get, put, delete and perhaps update) stores data it in an efficient structure. The index should remain in memory, and considering the amount of objects, the overhead must be small. The software should be able to handle massive connections with slow (if any) time needed to ramp up. Index should be read in memory at startup. Statistics would be nice, but not mandatory. I have experimented a bit with riak, redis, mongodb, kyoto and varnish with persistent storage, but I haven't had the chance to dig in really deep yet.

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To what extent is size a factor in SSD performance?

- by artif

To what extent is the size of an SSD a factor in its performance? In my mind, correct me if I'm wrong, a bigger SSD should be, everything else being equal, faster than a smaller one. A bigger SSD would have more erase blocks and thus more leeway for the FTL (flash translation layer) to do garbage collection optimization. Also there would be more time before TRIM became necessary. I see on Wikipedia that it remarks that "The performance of the SSD can scale with the number of parallel NAND flash chips used in the device" so it seems throughput also increases significantly. Also many SSDs contain internal caches of some sort and presumably those caches are larger for correspondingly large SSDs. But supposing this effect exists, I would like a quantitative analysis. Does throughput increase linearly? How much is garbage collection impacted, if at all? Does latency stay the same? And so on. Would the performance of a 8 GB SSD be significantly different from, for example, an 80 GB SSD assuming both used high quality chips, controllers, etc? Are there any resources (webpages, research papers, presentations, books, etc) that discuss correlations between SSD performance (4 KB random write speed, latency, maximum sequential throughput, etc) and size? I realize this does not really sound like a programming question but it is relevant for what I'm working on (using flash for caching hard drive data) which does involve programming. If there is a better place to ask this question, eg a more hardware oriented site, what would that be? Something like the equivalent of stack overflow (or perhaps a forum) for in-depth questions on hardware interfaces, internals, etc would be appreciated.

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How can I use HAproxy with SSL and get X-Forwarded-For headers AND tell PHP that SSL is in use?

- by Josh

I have the following setup: (internet) ---> [ pfSense Box ] /-> [ Apache / PHP server ] [running HAproxy] --+--> [ Apache / PHP server ] +--> [ Apache / PHP server ] \-> [ Apache / PHP server ] For HTTP requests this works great, requests are distributed to my Apache servers just fine. For SSL requests, I had HAproxy distributing the requests using TCP load balancing, and it worked however since HAproxy didn't act as a proxy, it didn't add the X-Forwarded-For HTTP header, and the Apache / PHP servers didn't know the client's real IP address. So, I added stunnel in front of HAproxy, reading that stunnel could add the X-Forwarded-For HTTP header. However, the package which I could install into pfSense does not add this header... also, this apparently kills my ability to use KeepAlive requests, which I would really like to keep. But the biggest issue which killed that idea was that stunnel converted the HTTPS requests into plain HTTP requests, so PHP didn't know that SSL was enabled and tried to redirect to the SSL site. How can I use HAproxy to load balance across a number of SSL servers, allowing those servers to both know the client's IP address and know that SSL is in use? And if possible, how can I do it on my pfSense server? Or should I drop all this and just use nginx?

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Amazon EC2: Instances, IPs and a wordpress blog (LAMP)

- by JustinXXVII

I had a link to my blog posted on Reddit yesterday and MySQL crashed on my EC2 Micro instance. I know I didn't have that many visitors because I used a marketing link that tracks hits. The link got 167 hits over the course of the last 18 hours, and MySQL crashed twice. So anyway, 167 visits is not a lot, so I've done some short term optimizations like restricting the number of Apache threads to limit the MySQL calls. I also set up WP Super Cache to serve static content. Soon I'm going to offload all of my images to S3 or CloudFront. So this leads me to my question. If this doesn't seem to help, and if i have another traffic "spike", how do AMIs work when you have a MySQL database? I think I understand that if you have more than one instance and assign the same Elastic IP to both of them, the incoming traffic gets distributed among both. But what happens when the MySQL database gets updated on one of the instances? I just need to wrap my mind around what happens when I create an AMI and then launch a new instance to help with traffic. Thanks for your suggestions.

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How to display/define Mirror/Stripping pairs with mdadm

- by Chris

I want to make a standard linux software Raid10 over 4 HDD. The server has 4HDDs, 2 pairs from different vendors in order to avoid batch problems. I want to have the mirror over two different Vendors, and then the Stripe over the mirror pairs. I could do that by manually creating Raid1/0, but mdadm supports Raid level 10. I just cant figure out how the Raid10 is then handled and how the data is distributed. mdadm --detail /dev/md10 /dev/md10: Version : 1.2 Creation Time : Wed May 28 11:06:23 2014 Raid Level : raid10 Array Size : 1953260544 (1862.77 GiB 2000.14 GB) Used Dev Size : 976630272 (931.39 GiB 1000.07 GB) Raid Devices : 4 Total Devices : 4 Persistence : Superblock is persistent Update Time : Wed May 28 11:06:23 2014 State : clean, resyncing (PENDING) Active Devices : 4 Working Devices : 4 Failed Devices : 0 Spare Devices : 0 Layout : near=2 Chunk Size : 512K Name : pdwhost:10 (local to host pdwhost) UUID : a3de0ad5:9e694ee1:addc6786:c4449e40 Events : 0 Number Major Minor RaidDevice State 0 8 1 0 active sync /dev/sda1 1 8 81 1 active sync /dev/sdf1 2 8 97 2 active sync /dev/sdg1 3 8 113 3 active sync /dev/sdh1 does not really give any information about that. How it should be: Raid 1 / Mirror over /dev/sda1 /dev/sdf1 and /dev/sdg1 /dev/sdh1 Raid 0 over the two Raid 1 pairs Is it possible to do that with the built in "level=10", how can I see what pairs are mirrored? Thanks a lot for you help

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