|
HTML rendering created 2026-09-09 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|
|
NAME | SYNOPSIS | DESCRIPTION | INSTALLATION | DEBUGGING OPTIONS | ENVIRONMENT | SEE ALSO | COLOPHON |
|
|
|
PMDABTRFS(1) General Commands Manual PMDABTRFS(1)
pmdabtrfs - btrfs filesystem performance metrics domain agent
(PMDA)
$PCP_PMDAS_DIR/btrfs/pmdabtrfs [-D debug] [-d domain] [-l logfile]
pmdabtrfs is a Performance Metrics Domain Agent (PMDA) which
extracts performance metrics from the btrfs filesystem via sysfs
(/sys/fs/btrfs).
The btrfs PMDA exports metrics covering filesystem information
(label, sizes, generation, checksum algorithm), transaction commit
statistics, space allocation for data, metadata and system block
groups, per-device error statistics, and async discard statistics.
Metrics are organized into two instance domains: one for btrfs
filesystems (keyed by UUID) and one for devices (keyed by
UUID::devid). Labels are provided for each instance, including
the filesystem UUID, label, and device ID where applicable.
A brief description of the pmdabtrfs command line options follows:
-d The performance metrics domain number must be set to a unique
value.
-l Location of the log file. By default, a log file named
btrfs.log is written in the current directory of pmcd(1) when
pmdabtrfs is started, i.e. $PCP_LOG_DIR/pmcd. If the log
file cannot be created or is not writable, output is written
to the standard error instead.
The btrfs PMDA requires a Linux system with one or more mounted
btrfs filesystems. The PMDA reads statistics from sysfs and does
not require root privileges.
Install the PMDA using the Install script:
# cd $PCP_PMDAS_DIR/btrfs
# ./Install
To remove the PMDA use the Remove script:
# cd $PCP_PMDAS_DIR/btrfs
# ./Remove
The -D or --debug option enables the output of additional
diagnostics on stderr to help triage problems, although the
information is sometimes cryptic and primarily intended to provide
guidance for developers rather end-users. debug is a comma
separated list of debugging options; use pmdbg(1) with the -l
option to obtain a list of the available debugging options and
their meaning.
Debugging options specific to pmdabtrfs are as follows:
┌────────┬───────────────────────────────────────────────────┐
│ Option │ Description │
├────────┼───────────────────────────────────────────────────┤
│ appl0 │ warn if the btrfs sysfs directory cannot be found │
└────────┴───────────────────────────────────────────────────┘
The BTRFS_PATH environment variable can be set to override the
default sysfs path (/sys/fs/btrfs) for testing purposes.
PCPIntro(1), pmcd(1), pcp.conf(5) and pcp.env(5).
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 2026-08-04.
(At that time, the date of the most recent commit that was found
in the repository was 2026-08-04.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
Performance Co-Pilot PCP PMDABTRFS(1)
|
HTML rendering created 2026-09-09 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|