pcp-dmcache(1) — Linux manual page


PCP-DMCACHE(1)             General Commands Manual            PCP-DMCACHE(1)

NAME         top

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

SYNOPSIS         top

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

DESCRIPTION         top

       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         top

       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).

SEE ALSO         top

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

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.
       Information about the project can be found at ⟨http://www.pcp.io/⟩.
       If you have a bug report for this manual page, send it to
       pcp@groups.io.  This page was obtained from the project's upstream
       Git repository ⟨https://github.com/performancecopilot/pcp.git⟩ on
       2020-11-01.  (At that time, the date of the most recent commit that
       was found in the repository was 2020-10-30.)  If you discover any
       rendering problems in this HTML version of the page, or you believe
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       (which is not part of the original manual page), send a mail to

Performance Co-Pilot                 PCP                      PCP-DMCACHE(1)