x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
DMEVENTD(8) System Manager's Manual DMEVENTD(8)
NAME
dmeventd -- Device-mapper event daemon
SYNOPSIS
dmeventd [-d [-d [-d]]] [-f] [-h] [-l] [-R] [-V] [-?]
DESCRIPTION
dmeventd is the event monitoring daemon for device-mapper devices. Li-
brary plugins can register and carry out actions triggered when partic-
ular events occur.
OPTIONS
-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 debug-
ging 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 ob-
tain a list of devices and events to monitor from the currently
running daemon.
-V Show version of dmeventd.
LVM PLUGINS
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_autoex-
tend_threshold. If the command fails, dmeventd thin plugin will
keep retrying execution with increasing time delay between re-
tries up to 42 minutes. User may also configure external com-
mand to support more advanced maintenance operations of a thin
pool. Such external command can e.g. remove some unneeded snap-
shots, 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 environ-
mental 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 warn-
ing 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 com-
mand fails, dmeventd vdo plugin will keep retrying execution
with increasing time delay between retries up to 42 minutes.
User may also configure external command to support more ad-
vanced maintenance operations of a VDO pool. Such external com-
mand 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
DMEVENTD_THIN_POOL_DATA
Variable is set by thin plugin and is available to executed pro-
gram. Value present actual usage of thin pool data volume. Vari-
able is not set when error event is processed.
DMEVENTD_THIN_POOL_METADATA
Variable is set by thin plugin and is available to executed pro-
gram. 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 pro-
gram. Value present actual usage of VDO pool data volume. Vari-
able is not set when error event is processed.
LVM_RUN_BY_DMEVENTD
Variable is set by thin and vdo plugin to prohibit recursive in-
teraction with dmeventd by any executed lvm2 command from a
thin_command, vdo_command environment.
SEE ALSO
lvm(8), lvm.conf(5), lvextend(8),
fstrim(8)
Red Hat Inc DM TOOLS 2.03.22(2) (2023-08-02) DMEVENTD(8)
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