pmdamemcache — memcached performance metrics domain agent (PMDA)
Description
This PMDA extracts performance data from memcached, a distributed memory caching daemon commonly used to improve web serving performance. A farm of memcached processes over multiple servers can be utilised by a single web application, increasing the total available object cache size, and decreasing the database load associated with smaller cache sizes. This system is described in detail at http://www.danga.com/memcached.
Installation
Configure pmdamemcache to extract the values from set of hosts used in the memcache farm. These hosts can be listed in the $PCP_PMDAS_DIR/memcache/memcache.conf file, in the format (i.e. Perl array) described at the top of pmdamemcache.pl. A custom refresh rate can also be configured using this mechanism.
# cd $PCP_PMDAS_DIR/memcache
# [ edit memcache.conf ]
Once this is setup, you can access the names and values for the memcache performance metrics by doing the following as root:
# cd $PCP_PMDAS_DIR/memcache
# ./Install
To uninstall, do the following as root:
# cd $PCP_PMDAS_DIR/memcache
# ./Remove
pmdamemcache is launched by pmcd(1) and should never be executed directly. The Install and Remove scripts notify pmcd(1) when the agent is installed or removed.
Files
- $PCP_PMDAS_DIR/memcache/memcache.conf
optional configuration file listing monitored memcache instances
- $PCP_PMDAS_DIR/memcache/Install
installation script for the pmdamemcache agent
- $PCP_PMDAS_DIR/memcache/Remove
undo installation script for the pmdamemcache agent
- $PCP_LOG_DIR/pmcd/memcache.log
default log file for error messages from pmdamemcache
PCP Environment
Environment variables with the prefix PCP_ are used to parameterize the file and directory names used by PCP. On each installation, the file /etc/pcp.conf contains the local values for these variables. The $PCP_CONF variable may be used to specify an alternative configuration file, as described in pcp.conf(5).