pmdamemcache1

Overview

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

If you want to undo the installation, 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).