bionic (8) dmeventd.8.gz

Provided by: dmeventd_1.02.145-4.1ubuntu3.18.04.3_amd64 bug

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.  Library plugins can register and
       carry out actions triggered when particular 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 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_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 program. Value present actual usage of
              thin pool data volume. Variable is not set when error event is processed.

       DMEVENTD_THIN_POOL_DATA
              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.

       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 ALSO

       lvm(8), lvm.conf(5)