демон событий mapper (mapper event daemon)
Имя (Name)
dmeventd — Device-mapper event daemon
Синопсис (Synopsis)
dmeventd [-d [-d [-d]]] [-f] [-h] [-l] [-R] [-V] [-?]
Описание (Description)
dmeventd is the event monitoring daemon for device-mapper
devices. Library plugins can register and carry out actions
triggered when particular events occur.
Параметры (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 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
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).
Переменные окружения (Environment variables)
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.
Смотри также (See also)
lvm(8), lvm.conf(5), lvextend(8),
fstrim(8)
