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.

PCP ENVIRONMENT         top

       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 2025-08-11.
       (At that time, the date of the most recent commit that was found
       in the repository was 2025-08-11.)  If you discover any rendering
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       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

Performance Co-Pilot               PCP                     PCP-DMCACHE(1)

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