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)

Red Hat Inc                             DM TOOLS 2.02.176(2) (2017-11-03)                            DMEVENTD(8)