NAME

       lvmetad — LVM metadata cache daemon

SYNOPSIS

       lvmetad  [-l level[,level...]]  [-p pidfile_path] [-s socket_path] [-t timeout_value] [-f]
       [-h] [-V] [-?]

DESCRIPTION

       The lvmetad daemon caches LVM metadata, so that LVM commands  can  read  metadata  without
       scanning disks.

       Metadata  caching  can  be  an  advantage because scanning disks is time consuming and may
       interfere with the normal work of the system and disks.

       lvmetad does not read metadata from disks itself.   The  'pvscan  --cache'  command  scans
       disks, reads the LVM metadata and sends it to lvmetad.

       New  LVM  disks  that  appear on the system must be scanned by pvscan before lvmetad knows
       about them.  If lvmetad does not know about a disk, then LVM commands using  lvmetad  will
       also  not know about it.  When disks are added or removed from the system, lvmetad must be
       updated.

       lvmetad is usually combined with event-based system services that automatically run pvscan
       --cache  on new disks.  This way, the lvmetad cache is automatically updated with metadata
       from new disks when they appear.  LVM udev  rules  and  systemd  services  implement  this
       automation.   Automatic  scanning is usually combined with automatic activation.  For more
       information, see pvscan(8).

       If lvmetad is started or restarted after disks have been added to the system,  or  if  the
       global_filter has changed, the cache must be updated by running 'pvscan --cache'.

       When lvmetad is not used, LVM commands revert to scanning disks for LVM metadata.

       Use of lvmetad is enabled/disabled by:
       lvm.conf(5) global/use_lvmetad

       For more information on this setting, see:
       lvmconfig --withcomments global/use_lvmetad

       To ignore disks from LVM at the system level, e.g. lvmetad, pvscan use:
       lvm.conf(5) devices/global_filter

       For more information on this setting, see
       lvmconfig --withcomments devices/global_filter

OPTIONS

       To  run  the daemon in a test environment both the pidfile_path and the socket_path should
       be changed from the defaults.

       -f     Don't fork, but run in the foreground.

       -h, -? Show help information.

       -l levels
              Specify the levels of log messages to generate as a comma separated list.  Messages
              are  logged  by  syslog.   Additionally,  when  -f  is  given they are also sent to
              standard error.  Possible levels are: all, fatal, error, warn, info, wire, debug.

       -p pidfile_path
              Path to the pidfile. This overrides both the  built-in  default  (/run/lvmetad.pid)
              and  the  environment  variable  LVM_LVMETAD_PIDFILE.  This file is used to prevent
              more than one instance of the daemon running simultaneously.

       -s socket_path
              Path  to  the   socket   file.   This   overrides   both   the   built-in   default
              (/run/lvm/lvmetad.socket)  and  the  environment  variable  LVM_LVMETAD_SOCKET.  To
              communicate successfully with lvmetad, all  LVM2  processes  should  use  the  same
              socket path.

       -t timeout_value
              The  daemon may shutdown after being idle for the given time (in seconds). When the
              option is omitted or the value given is zero the daemon never shutdowns on idle.

       -V     Display the version of lvmetad daemon.

ENVIRONMENT VARIABLES

       LVM_LVMETAD_PIDFILE
              Path for the pid file.

       LVM_LVMETAD_SOCKET
              Path for the socket file.

SEE ALSO

       lvm(8), lvmconfig(8), lvm.conf(5), pvscan(8)