DMEVENTD(8)DMEVENTD(8)NAMEdmeventd — Device-mapper event daemon
SYNOPSISdmeventd [-d [-d [-d]]] [-f] [-h] [-l] [-R] [-V] [-?]
DESCRIPTIONdmeventd is the event monitoring daemon for device-mapper devices.
Library plugins can register and carry out actions triggered when par‐
ticular 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
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 cur‐
rently 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
retries upto 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_DATA. 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_DATA
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.
LVM_RUN_BY_DMEVENTD
Variable is set by thin plugin to prohibit recursive interation
with dmeventd by any executed lvm2 command from a thin_command
environment.
SEE ALSOlvm(8), lvm.conf(5)Red Hat Inc DM TOOLS 2.02.176(2) (2017-11-03) DMEVENTD(8)
