| DMEVENTD(8) | System Manager's Manual | DMEVENTD(8) |
dmeventd — Device-mapper event daemon
dmeventd [-d [-d [-d]]] [-f] [-h] [-l] [-R] [-V] [-?]
dmeventd is the event monitoring daemon for device-mapper devices. Library plugins can register and carry out actions triggered when particular events occur.
-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.
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).
| DM TOOLS 2.03.11(2) (2021-01-08) | Red Hat Inc |