NAME

       pcp-dmcache, pcp-lvmcache - report on logical storage device caches

SYNOPSIS

       pcp [pcp options] dmcache [-iRV?] [device ...]

DESCRIPTION

       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.

OPTIONS

       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.

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).

       For environment variables affecting PCP tools, see pmGetOptions(3).

SEE ALSO

       PCPIntro(1), pcp(1), pmdadm(1), dmsetup(1) and lvmcache(7).