1DMEVENTD(8)                 System Manager's Manual                DMEVENTD(8)
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NAME

6       dmeventd — Device-mapper event daemon
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SYNOPSIS

9       dmeventd [-d [-d [-d]]] [-f] [-h] [-l] [-R] [-V] [-?]
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DESCRIPTION

12       dmeventd  is  the  event  monitoring  daemon for device-mapper devices.
13       Library plugins can register and carry out actions triggered when  par‐
14       ticular events occur.
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OPTIONS

17       -d
18              Repeat  from  1  to  3  times  ( -d, -dd, -ddd ) to increase the
19              detail of debug messages sent to syslog.  Each extra d adds more
20              debugging information.
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22       -f
23              Don't fork, run in the foreground.
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25       -h
26              Show help information.
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28       -l
29              Log  through  stdout  and stderr instead of syslog.  This option
30              works only with option -f, otherwise it is ignored.
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32       -?
33              Show help information on stderr.
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35       -R
36              Replace a running dmeventd instance. The running  dmeventd  must
37              be  version  2.02.77  or  newer.  The new dmeventd instance will
38              obtain a list of devices and events to  monitor  from  the  cur‐
39              rently running daemon.
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41       -V
42              Show version of dmeventd.
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LVM PLUGINS

45       Mirror
46              Attempts   to   handle   device   failure   automatically.   See
47              lvm.conf(5).
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49       Raid
50              Attempts   to   handle   device   failure   automatically.   See
51              lvm.conf(5).
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53       Snapshot
54              Monitors  how full a snapshot is becoming and emits a warning to
55              syslog when it exceeds 80% full.  The warning is  repeated  when
56              85%,  90%  and  95% of the snapshot is filled.  See lvm.conf(5).
57              Snapshot which runs out of space gets invalid  and  when  it  is
58              mounted, it gets umounted if possible.
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60       Thin
61              Monitors  how full a thin pool data and metadata is becoming and
62              emits a warning to syslog when it exceeds 80% full.  The warning
63              is  repeated when more then 85%, 90% and 95% of the thin pool is
64              filled. See lvm.conf(5).  When a thin pool fills over 50%  (data
65              or  metadata) thin plugin calls configured dmeventd/thin_command
66              with every 5% increase.  With default setting it calls  internal
67              lvm  lvextend  --use-policies to resize thin pool when it's been
68              filled above configured  threshold  activation/thin_pool_autoex‐
69              tend_threshold.  If the command fails, dmeventd thin plugin will
70              keep retrying  execution  with  increasing  time  delay  between
71              retries  upto 42 minutes.  User may also configure external com‐
72              mand to support more advanced maintenance operations of  a  thin
73              pool.  Such external command can e.g. remove some unneeded snap‐
74              shots, use fstrim(8) to free recover space in a thin  pool,  but
75              also  can  use lvextend --use-policies if other actions have not
76              released enough space.  Command is executed  with  environmental
77              variable  LVM_RUN_BY_DMEVENTD=1  so any lvm2 command executed in
78              this environment will not try to interact with dmeventd.  To see
79              the fullness of a thin pool command may check these two environ‐
80              mental       variables        DMEVENTD_THIN_POOL_DATA        and
81              DMEVENTD_THIN_POOL_METADATA.   Command can also read status with
82              tools like lvs(8).
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ENVIRONMENT VARIABLES

85       DMEVENTD_THIN_POOL_DATA
86              Variable is set by thin plugin and is available to executed pro‐
87              gram. Value present actual usage of thin pool data volume. Vari‐
88              able is not set when error event is processed.
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90       DMEVENTD_THIN_POOL_METADATA
91              Variable is set by thin plugin and is available to executed pro‐
92              gram.  Value  present actual usage of thin pool metadata volume.
93              Variable is not set when error event is processed.
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95       LVM_RUN_BY_DMEVENTD
96              Variable is set by thin plugin to prohibit recursive  interation
97              with  dmeventd  by any executed lvm2 command from a thin_command
98              environment.
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SEE ALSO

101       lvm(8), lvm.conf(5)
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105Red Hat Inc         DM TOOLS 2.02.180(2)-RHEL7 (2018-07-20)        DMEVENTD(8)
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