pcp [pcp options] dmcache [-iRV?] [device ...]
pcp-dmcache reports on the activity of any configured Device Mapper Cache targets. The reported information includes device IOPs, cache and metadata device utilization, as well as hit and miss rates and ratios for both reads and writes for each cache device.
pcp-lvmcache (Logical Volume Manager cache) is an exact synonym for pcp-dmcache (Device Mapper cache).
By default, pcp-dmcache reports on all available cache target devices (one line each, per sample), but this can be restricted to specific devices on the command line.
When invoked via the pcp(1) command, the -h/--host, -a/--archive, -O/--origin, -s/--samples, -t/--interval, -Z/--timezone and several other pcp options become indirectly available; refer to PCPIntro(1) for a complete description of these options.
The additional command line options available for pcp-dmcache are:
- -i, --iops
displays total read and write operations instead of the default cache hit ratio.
- -R, --repeat
changes the frequency at which the column heading is displayed. By default, a header is displayed after every tenth sample.
- -V, --version
Display version number and exit.
- -?, --help
Display usage message and exit.
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).
For environment variables affecting PCP tools, see pmGetOptions(3).
PCPIntro(1), pcp(1), pmdadm(1), dmsetup(1) and lvmcache(7).
The man page pcp-lvmcache(1) is an alias of pcp-dmcache(1).