DESCRIPTION

pmdadmcache is a Performance Metrics Domain Agent (PMDA) which exports metric values about device mapper cache target devices, made available by the dm-cache Linux kernel module.

The device mapper cache target aims to improve the performance of a block device (such as a spindle) by dynamically migrating some of its data to a faster, smaller device (such as a Solid State Drive).

This PMDA exports metrics for each configured cache, including sizes, cache read and write hits and misses, rates of cached block demotion and promotion, and the mode each cache is operating in.

INSTALLATION

Install the dmcache PMDA by using the Install script as root:

      # cd $PCP_PMDAS_DIR/dmcache

      # ./Install

To uninstall, do the following as root:

      # cd $PCP_PMDAS_DIR/dmcache

      # ./Remove

pmdadmcache 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/dmcache/Install

installation script for the pmdadmcache agent

$PCP_PMDAS_DIR/dmcache/Remove

undo installation script for the pmdadmcache agent

$PCP_LOG_DIR/pmcd/dmcache.log

default log file for error messages from pmdadmcache

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).