A location or process for storing of transitory or temporary data in order to improve application or system performance.

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52
votes
10answers
9k views

Why drop caches in Linux?

In our servers we have a habit of dropping caches at midnight. sync; echo 3 > /proc/sys/vm/drop_caches When I run the code it seems to free up lots of RAM, but do I really need to do that. ...
3
votes
3answers
2k views

What is the memory module on a RAID card needed for?

As above, what is the reason for needing a memory module on a RAID card? The card I am looking at (HP P410) comes with either 256MB or 512MB but unsure which to get and why.
13
votes
1answer
5k views

deleting linux cached ram [duplicate]

I have a webserver that has 8GB of ram and is running a pretty intensive php site (1 site) that does file manipulation, graphing, emailing, forums, you name it. The environment is far from static ...
15
votes
3answers
6k views

Is there a way to get Cache Hit/Miss ratios for block devices in Linux?

Is it possible to see in Linux how many read and write requests from user space end up causing cache hits and misses for block devices?
13
votes
6answers
8k views

SATA Disks that handle write caching properly?

It's pretty common to see advice to disable the write cache on individual disks used for databases because otherwise some disks will acknowledge writes that haven't yet made it to the disk surface. ...
36
votes
3answers
23k views

Disable caching when serving static files with Nginx (for development)

We are using Nginx to serve static files on a development platform. As it is a development platform, we'd like to disable caching so that each change is propagated to the server. The configuration of ...
17
votes
3answers
4k views

How effective is LSI CacheCade SSD storage tiering?

LSI offers their CacheCade storage tiering technology, which allows SSD devices to be used as read and write caches to augment traditional RAID arrays. Other vendors have adopted similar ...
5
votes
2answers
12k views

How can I cache YouTube videos with Squid Cache?

we're using the Squid cache in our company. Is there any way we can cache YouTube videos? cheers :)
2
votes
4answers
6k views

How to configure nginx to serve static contents from RAM?

I want to set up nginx as my web server. I want to have image files cached in the memory (RAM) rather then disk. I am serving a small page and want few images always served from RAM. I dont wish to ...
6
votes
5answers
3k views

Free / Cached / Available memory on Linux

I have read that linux uses free memory for caching, to make system faster. However, both Nagios and Paessler PRTG monitoring system show me that my memory usage is critical. I could change Nagios ...
3
votes
2answers
248 views

Is there an Elegant solution to rewrite long image?query-urls into cachable_nice_urls, using only apache htaccess?

this is a pain in the ass-problem! Whicever genius solves this riddle will receive paypal donation to eat diner for two. Now lets get started. Given: most proxies, do not cache resources with a "?" in ...
2
votes
2answers
94 views

linux caches route with IPs of machine it has no access to

I have a VPN with a gateway, and an application server. The app server only knows about the gateway of the VPN. The gateway of the VPN knows about the gateway of the physical network the vms are ...
1
vote
2answers
955 views

running nginx as a reverse proxy with apache

Q1) Do I need mod_deflate running on apache? does it help in performance in anyway? Q2) Do I need mod_cache running on apache if nginx is serving a static caching proxy? <IfModule mod_cache.c> ...
3
votes
2answers
969 views

Unexplained cache RAM drops on Linux machine

I run a CentOS 5.7 64 machine with 24gb ram and running kernel 2.6.18-274.12.1.el5. This machine runs only Nginx, php-fpm and Xcache as extra applications. Since about 3 weeks my memory behavior on ...
30
votes
5answers
22k views

Which PHP (opcode) cache one should use and why?

I keep hearing about some PHP (opcode) caches like - APC, XCache, Memcache, eAccelerator, etc. But I couldn't ever figure out how to go about choosing one. Apart from performance benefit, which a ...
7
votes
5answers
5k views

Squid or Other HTTP Caches with SSD Cache Store?

I'm contemplating setting up a squid (or possibly varnish) cache on a system with SSD drives. The obvious benefit is that these systems have great READ speeds and I expect my hit ratios to be fairly ...
11
votes
2answers
9k views

Varnish Cache - default TTL?

I have discovered that I can set the TTL in Varnish as follows in my VCL file: sub vcl_fetch { # 1 minute set obj.ttl = 1m; } But what is the default setting (assuming the backend server is ...
4
votes
3answers
156 views

What's a good resource for learning about scaling PHP applications?

I know PHP fairly well. But one aspect of PHP which I am fairly green in is caching, loading balancing etc. A lot of companies hiring PHP developers are looking for these high-use background, which ...
6
votes
1answer
4k views

Working Nginx fastcgi_cache php-fpm cache and static file caching configuration?

Nginx wiki is very vague with explanation as to how to properly setup nginx with php-fpm with fastcgi_caching for sites which have cookies i.e. wordpress, drupal, vbulletin etc. I downloaded a ...
1
vote
2answers
345 views

Selectively clearning cache/buffers

Is it possible to selectively clear content from a particular filesystem, or file/directory within a filesystem, under Linux. This can be done globally with sync; echo 3 > /proc/sys/vm/drop_caches ...
3
votes
1answer
313 views

My server doesn't seem to be caching anything well

I have a VPS from tocici (via BuildYourVPS). It's got 4 GB of RAM (2 GB of it "burst" RAM). This server has some severe performance issues, however. First, a quick explanation of what this server ...
3
votes
1answer
2k views

Does is matter in what order rules are placed in htaccess?

I hope this is a simple YES or NO answer (please specify why) Q1: Does is matter in what order the rules are placed in htaccess? Since they are completely separated items: for example Q2: If yes, am ...
3
votes
1answer
3k views

ASP.NET cache trimming aware of app pool memory limit?

I’m running a ASP.NET application on Win2003 32bit that tends to allocate a lot of memory. To avoid OutOfMemoryExceptions that start to appear when the W3P process exceeds 1 GB, I have set a maximum ...
3
votes
2answers
4k views

Apache redirect and set cache headers?

Doing a redirect in Apache is easy (mod_alias): RedirectMatch ^.*$ http://portal.example.com/ Setting cache headers is equally easy: Header set Cache-Control max-age=0 Header set Expires "Thu, 01 ...
2
votes
4answers
3k views

Is there a way to force windows to cache a file in RAM

I have a windows server 2008 R2 file server, that has some large files that on rare occasions is very important to get copied to another system as quickly as possible. Is there a way to force these ...
0
votes
1answer
200 views

url rewrite to make generated thumnails cache like static, a syntax question

this is a pain in the ass-problem!! Given: most proxies, do not cache resources with a "?" in their URL even if a Cache-control: public header is present in the response. To enable proxy caching for ...
5
votes
3answers
4k views

Making SATA disk write cache safe

Supposedly (see, e.g., a question about it here), with NCQ enabled drives, the drive write cache is supposed to be safe, as in it doesn't like to the OS about data being committed to the platters when ...
4
votes
1answer
185 views

Is this a case of a stale ISP DNS cache or did I fudge something up?

I am currently in the process of transferring a legacy website (from a legacy hosting service provider) to a modern solution. Due to my context-specific requirements (which include financial ...
4
votes
3answers
1k views

Varnish only cache assets from single session

Currently I manage to configure varnish to cache items from 1 user, but the when the second users comes in varnish fetch another asset from Apache. How can I cache static assets behind magento ( ...
2
votes
4answers
122 views

Is this a good behaviour? [duplicate]

My centos 5.7 is running Magento. 4GB RAM and 4 Cores. Nginx + spwan-fcgi + memcached (Best performance if you ask me). Now i'm a little bit concerned about the Memory usage. [root@adikastyle ...
2
votes
2answers
3k views

Avoiding Varnish Hitting Magento Cookies - VCL

Hello to serverfault users, I would like to kindly ask someone to help me configure varnish for magento. Using command: varnishtop -i TxHeader -I Cookie , following info show: TxHeader Cookie: ...
2
votes
1answer
430 views

Purging AD Principal from cache

A user in the Active Directory has had a change of his SAM account name, but a web application running IIS still recognizes him under his old SAM Account name. I presume this is because the AD ...
2
votes
5answers
4k views

Why does APC (or similar) cause performance problem for shared hosting?

I'm using shared hosting, and I can't enable APC. There was a thread about that here, and the only reason suggested was for security (php-cgi vs mod_php). I queried the host, and they said it was due ...
1
vote
2answers
607 views

Squid proxy refusing to revalidate cache when Vary header present

squid.conf cache_effective_user squid http_access allow all # Squid normally listens to port 3128 http_port 3128 accel defaultsite=localhost no-vhost ignore-cc cache_peer localhost parent 80 0 ...
1
vote
1answer
862 views

Push content to Apache Traffic Server's Cache

I am trying to use push cache option of Apache Traffic Server(ATS), to push some content into my cache. I read the documentation, and tried to follow it but I have following questions/problems using ...
1
vote
2answers
2k views

Why is IIS 7.5 flushing file cache very often?

We're running a Win 2008 R2 server with IIS 7.5 for serving image files. It's only used for static content, and file caching has been set up to cache files for 10 minutes. However the IIS frequently ...
1
vote
1answer
782 views

How to prevent the slow first load startup for a website?

I'm sure you've noticed that for many servers, the website loading time is quite long if you're the first visitor for a couple of hours. Do you have any idea why this is the case (is it just server ...
1
vote
1answer
566 views

HowTo turnoff Apache2 cache on Ubuntu? (solved)

Here is my problem: after default installation of apache2 for Ubuntu it's started to retrieve old pages for Trac, for example, I made a small changes (simply edit page) in trac-wiki section, push ...
1
vote
3answers
2k views

Torrent caching [closed]

I am looking for torrent caching software (like SQUID for http). Do you know any?
1
vote
1answer
2k views

Should I use Expires headers, Cache-Control headers, or both?

Just trying to do a bit of performance tuning on a client's site. I don't want to set far future expiries yet, because we are still changing a lot of stuff regularly, but I'd like to give everything ...
0
votes
3answers
163 views

Filesystem cache accessible via HTTP?

After searching the web for hours and couldn't find what I was looking for, I thought someone here might have an idea ;-) I'm looking for Linux a program that will cache in memory a designated ...
0
votes
1answer
224 views

Bad behaviour of native win32 application when replacing the exe with some users using it

I am using XP Unlimited to allow users do Remote Desktop on a Windows 7 machine. The users run on remote desktop a native win32 exe Application (built with Delphi). When I need to update the exe ...
0
votes
2answers
4k views

How to update domain password cache over vpn

I have a machine that connects to a domain over a VPN, however it hasn't connected for months and has an old domain password (that I have forgotten) cached on it and won't let me log in to the box ...
-1
votes
1answer
57 views

Debug Nginx caching

I want to determine when I am getting cache hits or misses. Preferably, this would be a header, like X-Cache: HIT or X-Cache: MISS How can I do this with Nginx (a reverse proxy for the upstream ...
-1
votes
1answer
433 views

How to arrange web servers with Varnish? [closed]

I am wondering what it the best (most stable with the least memory footprint) arrangment for a busy php+mysql app? request > Varnish > Apache requests > Varnish > Nginx > php5-fpm ...