1DMEVENTD(8) System Manager's Manual DMEVENTD(8)
2
6 dmeventd — Device-mapper event daemon
7
9 dmeventd [-d [-d [-d]]] [-f] [-h] [-l] [-R] [-V] [-?]
10
12 dmeventd is the event monitoring daemon for device-mapper devices. Li‐
13 brary plugins can register and carry out actions triggered when partic‐
14 ular events occur.
15
17 -d
18 Repeat from 1 to 3 times ( -d, -dd, -ddd ) to increase the de‐
19 tail of debug messages sent to syslog. Each extra d adds more
20 debugging information.
21 -f
23 Don't fork, run in the foreground.
24 -h
26 Show help information.
27 -l
29 Log through stdout and stderr instead of syslog. This option
30 works only with option -f, otherwise it is ignored.
31 -?
33 Show help information on stderr.
34 -R
36 Replace a running dmeventd instance. The running dmeventd must
37 be version 2.02.77 or newer. The new dmeventd instance will ob‐
38 tain a list of devices and events to monitor from the currently
39 running daemon.
40 -V
42 Show version of dmeventd.
43
45 Mirror
46 Attempts to handle device failure automatically. See
47 lvm.conf(5).
48 Raid
50 Attempts to handle device failure automatically. See
51 lvm.conf(5).
52 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.
59 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 re‐
71 tries upto 42 minutes. User may also configure external command
72 to support more advanced maintenance operations of a thin pool.
73 Such external command can e.g. remove some unneeded snapshots,
74 use fstrim(8) to free recover space in a thin pool, but also can
75 use lvextend --use-policies if other actions have not released
76 enough space. Command is executed with environmental variable
77 LVM_RUN_BY_DMEVENTD=1 so any lvm2 command executed in this envi‐
78 ronment will not try to interact with dmeventd. To see the
79 fullness of a thin pool command may check these two environmen‐
80 tal variables DMEVENTD_THIN_POOL_DATA and
81 DMEVENTD_THIN_POOL_METADATA. Command can also read status with
82 tools like lvs(8).
83 Vdo
86 Monitors how full a VDO pool data is becoming and emits a warn‐
87 ing to syslog when it exceeds 80% full. The warning is repeated
88 when more then 85%, 90% and 95% of the VDO pool is filled. See
89 lvm.conf(5). When a VDO pool fills over 50% vdo plugin calls
90 configured dmeventd/vdo_command with every 5% increase. With
91 default setting it calls internal lvm lvextend --use-policies to
92 resize VDO pool when it's been filled above the configured
93 threshold activation/vdo_pool_autoextend_threshold. If the com‐
94 mand fails, dmeventd vdo plugin will keep retrying execution
95 with increasing time delay between retries upto 42 minutes.
96 User may also configure external command to support more ad‐
97 vanced maintenance operations of a VDO pool. Such external com‐
98 mand can e.g. remove some unneeded space with fstrim(8), but
99 also can use lvextend --use-policies if other actions have not
100 released enough space. Command is executed with environmental
101 variable LVM_RUN_BY_DMEVENTD=1 so any lvm2 command executed in
102 this environment will not try to interact with dmeventd. To see
103 the fullness of a VDO pool command may check this environmental
104 variable DMEVENTD_VDO_POOL. Command can also read status with
105 tools like lvs(8).
106
108 DMEVENTD_THIN_POOL_DATA
109 Variable is set by thin plugin and is available to executed pro‐
110 gram. Value present actual usage of thin pool data volume. Vari‐
111 able is not set when error event is processed.
112 DMEVENTD_THIN_POOL_METADATA
114 Variable is set by thin plugin and is available to executed pro‐
115 gram. Value present actual usage of thin pool metadata volume.
116 Variable is not set when error event is processed.
117 DMEVENTD_VDO_POOL
119 Variable is set by vdo plugin and is available to executed pro‐
120 gram. Value present actual usage of VDO pool data volume. Vari‐
121 able is not set when error event is processed.
122 LVM_RUN_BY_DMEVENTD
124 Variable is set by thin and vdo plugin to prohibit recursive in‐
125 teration with dmeventd by any executed lvm2 command from a
126 thin_command, vdo_command environment.
127
129 lvm(8), lvm.conf(5)
130Red Hat Inc DM TOOLS 2.03.11(2) (2021-01-08) DMEVENTD(8)