1LVMETAD(8) System Manager's Manual LVMETAD(8)
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6 lvmetad — LVM metadata cache daemon
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10 lvmetad [-l level[,level...]] [-p pidfile_path] [-s socket_path] [-t
11 timeout_value] [-f] [-h] [-V] [-?]
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15 The lvmetad daemon caches LVM metadata, so that LVM commands can read
16 metadata without scanning disks.
17 Metadata caching can be an advantage because scanning disks is time
19 consuming and may interfere with the normal work of the system and
20 disks.
21 lvmetad does not read metadata from disks itself. The 'pvscan --cache'
23 command scans disks, reads the LVM metadata and sends it to lvmetad.
24 New LVM disks that appear on the system must be scanned by pvscan
26 before lvmetad knows about them. If lvmetad does not know about a
27 disk, then LVM commands using lvmetad will also not know about it.
28 When disks are added or removed from the system, lvmetad must be
29 updated.
30 lvmetad is usually combined with event-based system services that auto‐
32 matically run pvscan --cache on new disks. This way, the lvmetad cache
33 is automatically updated with metadata from new disks when they appear.
34 LVM udev rules and systemd services implement this automation. Auto‐
35 matic scanning is usually combined with automatic activation. For more
36 information, see pvscan(8).
37 If lvmetad is started or restarted after disks have been added to the
39 system, or if the global_filter has changed, the cache must be updated
40 by running 'pvscan --cache'.
41 When lvmetad is not used, LVM commands revert to scanning disks for LVM
43 metadata.
44 Use of lvmetad is enabled/disabled by:
46 lvm.conf(5) global/use_lvmetad
47 For more information on this setting, see:
49 lvmconfig --withcomments global/use_lvmetad
50 To ignore disks from LVM at the system level, e.g. lvmetad, pvscan use:
52 lvm.conf(5) devices/global_filter
53 For more information on this setting, see
55 lvmconfig --withcomments devices/global_filter
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59 To run the daemon in a test environment both the pidfile_path and the
60 socket_path should be changed from the defaults.
61 -f Don't fork, but run in the foreground.
63 -h, -? Show help information.
65 -l levels
67 Specify the levels of log messages to generate as a comma sepa‐
68 rated list. Messages are logged by syslog. Additionally, when
69 -f is given they are also sent to standard error. Possible lev‐
70 els are: all, fatal, error, warn, info, wire, debug.
71 -p pidfile_path
73 Path to the pidfile. This overrides both the built-in default
74 (/var/run/lvmetad.pid) and the environment variable
75 LVM_LVMETAD_PIDFILE. This file is used to prevent more than one
76 instance of the daemon running simultaneously.
77 -s socket_path
79 Path to the socket file. This overrides both the built-in
80 default (/var/run/lvm/lvmetad.socket) and the environment vari‐
81 able LVM_LVMETAD_SOCKET. To communicate successfully with
82 lvmetad, all LVM2 processes should use the same socket path.
83 -t timeout_value
85 The daemon may shutdown after being idle for the given time (in
86 seconds). When the option is omitted or the value given is zero
87 the daemon never shutdowns on idle.
88 -V Display the version of lvmetad daemon.
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92 LVM_LVMETAD_PIDFILE
93 Path for the pid file.
94 LVM_LVMETAD_SOCKET
96 Path for the socket file.
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100 lvm(8), lvmconfig(8), lvm.conf(5), pvscan(8)
101Red Hat Inc LVM TOOLS 2.02.143(2)-RHEL6 (2016-12-13) LVMETAD(8)