dmeventd(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | LVM PLUGINS | ENVIRONMENT VARIABLES | SEE ALSO | COLOPHON

DMEVENTD(8)              System Manager's Manual             DMEVENTD(8)

NAME         top

       dmeventd — Device-mapper event daemon

SYNOPSIS         top

       dmeventd [-d [-d [-d]]] [-f] [-h] [-l] [-R] [-V] [-?]

DESCRIPTION         top

       dmeventd is the event monitoring daemon for device-mapper
       devices.  Library plugins can register and carry out actions
       triggered when particular events occur.

OPTIONS         top

       -d     Repeat from 1 to 3 times (-d, -dd, -ddd) to increase the
              detail of debug messages sent to syslog.  Each extra d
              adds more debugging information.

       -f     Don't fork, run in the foreground.

       -h     Show help information.

       -l     Log through stdout and stderr instead of syslog.  This
              option works only with option -f, otherwise it is ignored.

       -?     Show help information on stderr.

       -R     Replace a running dmeventd instance. The running dmeventd
              must be version 2.02.77 or newer. The new dmeventd
              instance will obtain a list of devices and events to
              monitor from the currently running daemon.

       -V     Show version of dmeventd.

LVM PLUGINS         top

       Mirror Attempts to handle device failure automatically.
              See lvm.conf(5).

       Raid   Attempts to handle device failure automatically.
              See lvm.conf(5).

       Snapshot
              Monitors how full a snapshot is becoming and emits a
              warning to syslog when it exceeds 80% full.  The warning
              is repeated when 85%, 90% and 95% of the snapshot is
              filled.  See lvm.conf(5).  Snapshot which runs out of
              space gets invalid and when it is mounted, it gets
              umounted if possible.

       Thin   Monitors how full a thin pool data and metadata is
              becoming and emits a warning to syslog when it exceeds 80%
              full.  The warning is repeated when more then 85%, 90% and
              95% of the thin pool is filled. See lvm.conf(5).  When a
              thin pool fills over 50% (data or metadata) thin plugin
              calls configured dmeventd/thin_command with every 5%
              increase.  With default setting it calls internal lvm
              lvextend --use-policies to resize thin pool when it's been
              filled above configured threshold
              activation/thin_pool_autoextend_threshold.  If the command
              fails, dmeventd thin plugin will keep retrying execution
              with increasing time delay between retries upto 42
              minutes.  User may also configure external command to
              support more advanced maintenance operations of a thin
              pool.  Such external command can e.g. remove some unneeded
              snapshots, use fstrim(8) to free recover space in a thin
              pool, but also can use lvextend --use-policies if other
              actions have not released enough space.  Command is
              executed with environmental variable LVM_RUN_BY_DMEVENTD=1
              so any lvm2 command executed in this environment will not
              try to interact with dmeventd.  To see the fullness of a
              thin pool command may check these two environmental
              variables DMEVENTD_THIN_POOL_DATA and DMEVENTD_THIN_POOL_
              METADATA.  Command can also read status with tools like
              lvs(8).

       Vdo    Monitors how full a VDO pool data is becoming and emits a
              warning to syslog when it exceeds 80% full.  The warning
              is repeated when more then 85%, 90% and 95% of the VDO
              pool is filled. See lvm.conf(5).  When a VDO pool fills
              over 50% vdo plugin calls configured dmeventd/vdo_command
              with every 5% increase.  With default setting it calls
              internal lvm lvextend --use-policies to resize VDO pool
              when it's been filled above the configured threshold
              activation/vdo_pool_autoextend_threshold.  If the command
              fails, dmeventd vdo plugin will keep retrying execution
              with increasing time delay between retries upto 42
              minutes.  User may also configure external command to
              support more advanced maintenance operations of a VDO
              pool.  Such external command can e.g. remove some unneeded
              space with fstrim(8), but also can use lvextend
              --use-policies if other actions have not released enough
              space.  Command is executed with environmental variable
              LVM_RUN_BY_DMEVENTD=1 so any lvm2 command executed in this
              environment will not try to interact with dmeventd.  To
              see the fullness of a VDO pool command may check this
              environmental variable DMEVENTD_VDO_POOL.  Command can
              also read status with tools like lvs(8).

ENVIRONMENT VARIABLES         top

       DMEVENTD_THIN_POOL_DATA
              Variable is set by thin plugin and is available to
              executed program. Value present actual usage of thin pool
              data volume. Variable is not set when error event is
              processed.

       DMEVENTD_THIN_POOL_METADATA
              Variable is set by thin plugin and is available to
              executed program. Value present actual usage of thin pool
              metadata volume. Variable is not set when error event is
              processed.

       DMEVENTD_VDO_POOL
              Variable is set by vdo plugin and is available to executed
              program. Value present actual usage of VDO pool data
              volume. Variable is not set when error event is processed.

       LVM_RUN_BY_DMEVENTD
              Variable is set by thin and vdo plugin to prohibit
              recursive interation with dmeventd by any executed lvm2
              command from a thin_command, vdo_command environment.

SEE ALSO         top

       lvm(8), lvm.conf(5), lvextend(8),
       fstrim(8)

COLOPHON         top

       This page is part of the lvm2 (Logical Volume Manager 2) project.
       Information about the project can be found at 
       ⟨http://www.sourceware.org/lvm2/⟩.  If you have a bug report for
       this manual page, see ⟨https://github.com/lvmteam/lvm2/issues⟩.
       This page was obtained from the tarball
       https://github.com/lvmteam/lvm2/archive/refs/tags/v2_03_13.tar.gz
       fetched from ⟨https://github.com/lvmteam/lvm2/releases⟩ on
       2021-08-27.  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

Red Hat Inc         DM TOOLS 2.03.13(2) (2021-08-11)         DMEVENTD(8)

Pages that refer to this page: lvmraid(7)lvchange(8)lvconvert(8)lvcreate(8)lvdisplay(8)lvextend(8)lvm(8)lvmconfig(8)lvmdevices(8)lvmdiskscan(8)lvm-fullreport(8)lvm-lvpoll(8)lvreduce(8)lvremove(8)lvrename(8)lvresize(8)lvs(8)lvscan(8)pvchange(8)pvck(8)pvcreate(8)pvdisplay(8)pvmove(8)pvremove(8)pvresize(8)pvs(8)pvscan(8)vgcfgbackup(8)vgcfgrestore(8)vgchange(8)vgck(8)vgconvert(8)vgcreate(8)vgdisplay(8)vgexport(8)vgextend(8)vgimport(8)vgimportclone(8)vgimportdevices(8)vgmerge(8)vgmknodes(8)vgreduce(8)vgremove(8)vgrename(8)vgs(8)vgscan(8)vgsplit(8)