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Our memcached setup is currently only used for wiki sessions. With mediawiki, sessions stored in files over NFS or in the DB are very slow. Memcached is a non-blocking solution for our session storage. | |||
== Contact Information == | == Contact Information == | ||
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Purpose: Provide caching for Fedora web applications. | Purpose: Provide caching for Fedora web applications. | ||
== Checking Status == | == Checking Status == | ||
Revision as of 20:16, 17 February 2009
Our memcached setup is currently only used for wiki sessions. With mediawiki, sessions stored in files over NFS or in the DB are very slow. Memcached is a non-blocking solution for our session storage.
Contact Information
Owner: Fedora Infrastructure Team
Contact: #fedora-admin, sysadmin-main, sysadmin-web groups
Location: PHX
Servers: app1, app2
Purpose: Provide caching for Fedora web applications.
Checking Status
Our memcached instances are currently firewalled to only allow access from wiki application servers. To check the status of an instance, use:
echo stats | nc app{1,2} 11211
from an allowed host.
Restarting Memcached
Note that restarting an memcached instance will drop all sessions stored on that instance. As mediawiki uses hashing to distribute sessions across multiple instances, restarting one out of two instances will result in about half of the total sessions being dropped.
To restart memcached:
sudo /etc/init.d/memcached restart
Configuring Memcached
Memcached is currently setup as a module in the puppet git repo. The main two tunables are the MAXCONN (the maximum number of concurrent connections) and CACHESIZE (the amount memory to use for storage). These variables can be set through $memcached_maxconn and $memcached_cachesize in puppet. Additionally, other options (as described in the memcached manpage) can be set via $memcached_options.