Squids
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|pmtpa || sq16-sq40<br><tt>208.80.152.2</tt> || sq1-sq15, sq41-sq50<br><tt>208.80.152.3</tt> | |pmtpa || sq16-sq40<br><tt>208.80.152.2</tt> || sq1-sq15, sq41-sq50<br><tt>208.80.152.3</tt> | ||
|- | |- | ||
| − | |knams || knsq1-knsq7<br><tt>91.198.174.2</tt> || knsq8 - | + | |knams || knsq1-knsq7, knsq23-30<br><tt>91.198.174.2</tt> || knsq8 - knsq22<br><tt>91.198.174.3</tt> |
|- | |- | ||
|yaseo || yf1000-yf1004<br><tt>203.212.189.253</tt> || yf1005 - yf1009<br><tt>203.212.189.254</tt> | |yaseo || yf1000-yf1004<br><tt>203.212.189.253</tt> || yf1005 - yf1009<br><tt>203.212.189.254</tt> | ||
Revision as of 19:34, 23 July 2008
There are 6 clusters of squid servers, one upload and one text at each of our three locations: yaseo, knams and pmpta. Each server runs two instances of squid: a frontend squid listening on port 80, and a cache squid listening on port 3128. The purpose of the frontend squid is to distribute load to the cache squids based on URL hash, using the CARP algorithm.
LVS is used to balance incoming requests between the CARP frontends.
Contents |
Squid cluster distribution
| text | upload | |
|---|---|---|
| pmtpa | sq16-sq40 208.80.152.2 |
sq1-sq15, sq41-sq50 208.80.152.3 |
| knams | knsq1-knsq7, knsq23-30 91.198.174.2 |
knsq8 - knsq22 91.198.174.3 |
| yaseo | yf1000-yf1004 203.212.189.253 |
yf1005 - yf1009 203.212.189.254 |
Installation
All Wikimedia squids are running ubuntu. All necessary packages for squid can be installed by installing the wikimedia-task-squid package from the Wikimedia APT repository.
To reinstall a previously existing Squid server:
- Save the SSH hostkeys
- Reinstall the server using PXE
- After boot, copy the old SSH hostkey back using scp -o StrictHostKeyChecking=no files hostname:/etc/ssh/
- Log in, and set the root password
- # apt-get install wikimedia-task-squid (Answer the question about the LVS service IP very carefully)
- From zwinger, do: cd /home/w/conf/squid/ && make && ./deploy hostname
- (upload squids only) Run # setup-aufs-cachedirs to set up the AUFS cache partition. This will wipe any previous AUFS partition/data!
- If the Squid had not been running for a long time, clean the cache with /etc/init.d/squid clean
- Anything under ~2 hours and the cache does not need to be cleaned.
- # /etc/init.d/squid start
- Wait a few minutes after starting the backend here to start the frontend.
- You can watch TOP and see when the squid process slows down, or just read /var/log/squid/cache.log
- # /etc/init.d/squid-frontend start
- Install ganglia gmond
Configuration
Configuration is done by editing the master files in /home/wikipedia/conf/squid, then running make to rebuild the configuration files, and ./deploy to deploy them to the remote servers. The configuration files are:
- squid.conf.php
- Template file for the cache (backend) instances
- frontend.conf.php
- Template file for the frontend instances
- text-settings.php
- A settings array which applies to text squids. All elements in this array will become available as variables during execution of squid.conf.php and frontend.conf.php. The settings array can be used to give server-specific configuration.
- upload-settings.php
- Same as text-settings.php but for upload squids
- common-acls.conf
- ACL directives used by both text and upload frontends. Use this to block clients from all access.
- upload-acls.conf
- ACL directives used by upload frontends. Use this for e.g. image referrer regex blocks.
- text-acls.conf
- ACL directives used by text frontends. Use this for e.g. remote loader IP blocks.
- Configuration.php
- Contains most of the generator code
- generate.php
- the script that the makefile runs
Feel free to check in your changes to RCS.
The deployment script has lots of options. Run it with no arguments to get a summary.
Current problems
(none)
See also
- MediaWiki caching -- some cache headers explained
- Multicast HTCP purging -- new method of cache purging
- Squid logging
- Squid log format
