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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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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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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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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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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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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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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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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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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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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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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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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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Cache Control Headers with IIS 7.5

- by Brad

I'm trying to wrap my head around client side (web browser) caching and how it works in relation to IIS 7.5 cache control headers. In particular: If we want to force clients to reload cached resources, how must IIS be configured? Do we need to set expire web content immediately if the resources on the server have a more recent Modified Date (or ETag value)? Right now we're not setting any cache headers. So if I set a cache header of no-cache (which I think is the equivalent of expire web content immediately) will that force the web browser to obtain a new version of a particular file. Or will the browser only request a new version after it deems its current copy to be stale and then from that point forward not cache it? Would a best practice be to set a cache control flag of 1 week, then 8 days before I know I am going to make a change set the cache control down to for instance 30 minutes? But if I do that and then need to immediately expire an item from users caches because there was an issue with it how do I do that?

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Servers - Buying New vs Buying Second-hand

- by Django Reinhardt

We're currently in the process of adding additional servers to our website. We have a pretty simple topology planned: A Firewall/Router Server infront of a Web Application Server and Database Server. Here's a simple (and technically incorrect) diagram that I used in a previous question to illustrate what I mean: We're now wondering about the specs of our two new machines (the Web App and Firewall servers) and whether we can get away with buying a couple of old servers. (Note: Both machines will be running Windows Server 2008 R2.) We're not too concerned about our Firewall/Router server as we're pretty sure it won't be taxed too heavily, but we are interested in our Web App server. I realise that answering this type of question is really difficult without a ton of specifics on users, bandwidth, concurrent sessions, etc, etc., so I just want to focus on the general wisdom on buying old versus new. I had originally specced a new Dell PowerEdge R300 (1U Rack) for our company. In short, because we're going to be caching as much data as possible, I focussed on Processor Speed and Memory: Quad-Core Intel Xeon X3323 2.5Ghz (2x3M Cache) 1333Mhz FSB 16GB DDR2 667Mhz But when I was looking for a cheap second-hand machine for our Firewall/Router, I came across several machines that made our engineer ask a very reasonable question: If we stuck a boat load of RAM in this thing, wouldn't it do for the Web App Server and save us a ton of money in the process? For example, what about a second-hand machine with the following specs: 2x Dual-Core AMD Opteron 2218 2.6Ghz (2MB Cache) 1000Mhz HT 16GB DDR2 667Mhz Would it really be comparable with the more expensive (new) server above? Our engineer postulated that the reason companies upgrade their servers to newer processors is often because they want to reduce their power costs, and that a 2.6Ghz processor was still a 2.6Ghz processor, no matter when it was made. Benchmarks on various sites don't really support this theory, but I was wondering what server admin thought. Thanks for any advice.

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Strategy for Incremental Datasource fetchings in Excel

- by user1352530

I am in an scenario with a table that is refresh by a third app every week. I need to keep accumulating all data in Excel, using an ODBC connection to the database. I am wondering Approach 1: Is there a way to force Excel to append results for every update (this update would be triggered according to a parameter that indicates week)? I tried to define the table for which the connection loads using a dynamic reference but once is anchored first time, table position is never redefined Approach 2: Use an ETL to accumulate all weekly results into a staging table and then connect Excel to it in real time. But, I would need a mechanism for caching old data, as I cannot grow exponentially the time Excel opens. Imagine after 10 years, Excel would need to update at opening 10 years fo data before showing it. Is there a way to store already fetched data and increment it at real time (when book is opened) by selecting new data (with a query/filter of something) Thanks EDIT: Maybe it's better to ask it that way: What is the optimal strategy for a table that keeps growing and needs to be read in real time by Excel? I just don't want to fetch absolutely all data after some months...

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Why does lighttpd keep static files in cache, even when modified on disk ?

- by Pixelastic

I am using lighttpd to serve static files. I have a bunch of images in a dir that I regularly update. This will change the file content (and filesize) as well as the modification date, but not their filename. When I access the files through http, the updates are not taken into account and lighty serves the old file. I can manually rename the file to something different, then lighttpd will return a 404 error, and if I rename my file back, I will get the correct updated version. Seems like lightty is using some kind of cache mechanism of its own (which is fine) to return static files. Unfortunatly, it seems that this mechanism doesn't update itself when files are modified. I checked through Wireshark, and my browser is really doing a request to the file, this is not a browser caching issue. It returns a 200 OK when requesting it from an empty cache, and a 304 Not Modified otherwise, as expected. But the file is returned with a wrong Last-Modified header that do not reflect the real last modification date. Maybe there is some config directive that I am not aware of ? I would like the files returned by lighty to reflect the changes made on disk directly, or at least being able to invalidate its cache.

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How do I speed up and cache mmap file access over NFS on Linux?

- by Zan Lynx

The server and client are both 64-bit Ubuntu 10.04 LTS. The application in question is a custom app that uses mmap() for fast random file access. Its ideal state is when the entire file is cached in RAM. The network connections are really fast 10Gb Ethernet. It is a virtual server blade setup. It isn't the network connections slowing things down because everything performs superbly when using a virtual disk (iSCSI to the SAN). But when we run the application on a NFS home directory mount, performance goes to the dogs. It appears that the Linux kernel isn't caching anything. So it is reading every single disk block needed by mmap() accesses over and over and over again. The NFS mount is done through autofs, which has only default settings. /proc/mounts shows the NFS mount is done with the following options: rw,relatime,vers=3,rsize=131072,wsize=131072,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=192.168.11.52,mountvers=3,mountproto=tcp,addr=192.168.11.52 How can I make Ubuntu 10.04 cache the file instead of reloading it all the time?

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Is NFS capable of preserving order of operations?

- by JustJeff

I have a diskless host 'A', that has a directory NFS mounted on server 'B'. A process on A writes to two files F1 and F2 in that directory, and a process on B monitors these files for changes. Assume that B polls for changes faster than A is expected to make them. Process A seeks the head of the files, writes data, and flushes. Process B seeks the head of the files and does reads. Are there any guarantees about how the order of the changes performed by A will be detected at B? Specifically, if A alternately writes to one file, and then the other, is it reasonable to expect that B will notice alternating changes to F1 and F2? Or could B conceivably detect a series of changes on F1 and then a series on F2? I know there are a lot of assumptions embedded in the question. For instance, I am virtually certain that, even operating on just one file, if A performs 100 operations on the file, B may see a smaller number of changes that give the same result, due to NFS caching some of the actions on A before they are communicated to B. And of course there would be issues with concurrent file access even if NFS weren't involved and both the reading and the writing process were running on the same real file system. The reason I'm even putting the question up here is that it seems like most of the time, the setup described above does detect the changes at B in the same order they are made at A, but that occasionally some events come through in transposed order. So, is it worth trying to make this work? Is there some way to tune NFS to make it work, perhaps cache settings or something? Or is fine-grained behavior like this just too much expect from NFS?

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Domain joining debate for Outlook 2010 with Exchange 2007 on windows SBS 2008 for a user on a laptop that will travel a fair amount of the time.

- by user71195

I'm basically debating on whether or not to join the Domain on a Laptop, and was wondering if anyone has had a similar experience. If the computer were staying in the office, its a no brainer. Join the domain. In this case I have a user who will come into the office a few days a week, and work remotely the rest of the time. There is a working VPN using OpenVPN client/server, but it's not site-to-site. My knee jerk reaction is to not join the domain, so that the user can have 1 profile that they always use. In this configuration, should Outlook work properly with the user's domain account, and should the shared calendar still work (at least once inside the VPN)? My concern with joining the domain would be the inability to login to it when elsewhere. Is there maybe a way around this with caching or something? Would creating a second local login make sense for a user like this in any way? If so, why not just skip the domain join to begin with? Any thoughts on or experiences with this would be appreciated. Laptop OS Windows 7 (Not purchased yet.. pro if domain needed) Server SBS 2008, Exchange 2007 Outlook version 2010 Thanks for any help, Mike

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Nginx Removes the index.php from URL

- by codeHead

I have a codeigniter php application on nginx. It works as expected on Apache but after moving to nginx, I noticed that the index.php is automatically removed from the URL in all my links. Infact when I try using index.php it does not go to the desired URL but gets redirected to my default controller. below is a coopy of my nginx.conf file. server{ listen 80; server_name mydomainname.com; root /var/www/domain/current; # index index.php; error_log /var/log/nginx/error.log; access_log /var/log/nginx/access.log main; location / { # Check if a file or directory index file exists, else route it to index.php. try_files $uri $uri/ /index.php ; } location ~* \.php { fastcgi_pass backend; include fastcgi.conf; fastcgi_buffer_size 128k; fastcgi_buffers 4 256k; fastcgi_busy_buffers_size 256k; fastcgi_read_timeout 500; #fastcgi_param SCRIPT_FILENAME $document_root/index.php; add_header Expires "Thu, 01 Jan 1970 00:00:01 GMT"; add_header Cache-Control "no-cache, no-store, private, proxy-revalidate, must-revalidate, post-check=0, pre-check=0"; add_header Pragma no-cache; add_header X-Served-By $hostname; } location ~* ^.+\.(css|js)$ { expires 7d; add_header Pragma public; add_header Cache-Control "public"; } # set expiration of assets to MAX for caching location ~* \.(ico|gif|jpe?g|png)(\?[0-9]+)?$ { expires max; log_not_found on; } } I need to use my URL With the index.php -- please help.

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Let varnish send old data from cache while it's fetching a new one?

- by mark

I'm caching dynamically generated pages (PHP-FPM, NGINX) and have varnish in front of them, this works very well. However, once the cache timeout is reached, I see this: new client requests page varnish recognizes the cache timeout client waits varnish fetches new page from backend varnish delivers new page to the client (and has page cached, too, for the next request which gets it instantly) What I would like to do is: client requests page varnish recognizes the timeout varnish delivers old page to the client varnish fetches new page from backend and puts it into the cache In my case it's not site where outdated information is such a big problem, especially not when we're talking about cache timeout from a few minutes. However, I don't want punish user to wait in line and rather deliver something immediate. Is that possible in some way? To illustrate, here's a sample output of running siege 5 minutes against my server which was configured to cache for one minute: HTTP/1.1,200, 1.97, 12710,/,1,2013-06-24 00:21:06 ... HTTP/1.1,200, 1.88, 12710,/,1,2013-06-24 00:21:20 ... HTTP/1.1,200, 1.93, 12710,/,1,2013-06-24 00:22:08 ... HTTP/1.1,200, 1.89, 12710,/,1,2013-06-24 00:22:22 ... HTTP/1.1,200, 1.94, 12710,/,1,2013-06-24 00:23:10 ... HTTP/1.1,200, 1.91, 12709,/,1,2013-06-24 00:23:23 ... HTTP/1.1,200, 1.93, 12710,/,1,2013-06-24 00:24:12 ... I left out the hundreds of requests running in 0.02 or so. But it still concerns me that there are going to be users having to wait almost 2 seconds for their raw HTML. Can't we do any better here? (I came across Varnish send while cache , it sounded similar but not exactly what I'm trying to do.)

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How much free memory should I have on my webserver?

- by neanderslob

I have a webserver that's currently hosting two Wordpress sites and some java-based collaboration software. The server has 2G of memory and is currently using about 1.8G of the available memory. Right now what's on here is pretty much a pilot project that's getting negligible traffic so I think it's pretty clear that I'll be needing more memory. I was wondering, if I was to release it, how I might anticipate my memory needs based on the traffic it gets. I've poked around on Google and what I've found has been a bit tenuous. Is there a good heuristic that one should use when calculating memory demands as a function of the base (no traffic) load on the server? For reference, the output of free -m can be seen below: total used free shared buffers cached Mem: 2048 1832 215 0 0 0 -/+ buffers/cache: 1832 215 Swap: 0 0 0 To me this looks like actual memory used and isn't an illusion due to caching or anything else. I figure the demands of my collaboration software will have to be experimentally tested so here's free -m without that software running: total used free shared buffers cached Mem: 2048 1109 938 0 0 0 -/+ buffers/cache: 1109 938 Swap: 0 0 0 My plan B to figure this out is to add a bunch of swap space to the server, give it some traffic and adjust according the the amount that swap gets used. I was just wondering if anyone had a good rule of thumb to estimate how much memory I should plan on in advance...or if what I'm thinking is nuts. Many thanks in advance (I'm really quite new to this).

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Why won't Google Chrome open Google Docs, and why is it slow with GMail?

- by Philip

OSX 10.6 Snow Leopard: Google Chrome works like a charm most of the time. I have many extensions installed, and I've tried disabling/re-enabling them one by one to find a culprit, with no luck. Here are the problems: (1) Chrome is slow to load GMail. I am fairly sure that clearing the cache alleviates this problem. But I can open Safari, type in the URL, and login to GMail in the time it sometimes takes Chrome to open the page. Shouldn't caching help the page load?!? And sometimes even after recent cache clears it still is slow to load..... Thoughts? (2) Chrome won't open Google Docs at all. Safari does. Again, I tried disabling extensions one-by-one, and I allow cookies and even third-party cookies. But I still am told it has a redirect loop. Any help would be much appreciated. Thanks!

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