xenial (8) pvscan.8.gz

NAME

       pvscan — scan all disks for physical volumes

SYNOPSIS

       pvscan    [--commandprofile    ProfileName]    [-d|--debug]    [-h|--help]   [-v|--verbose]   [--version]
       [--ignorelockingfailure] [-e|--exported] [-n|--novolumegroup] [-s|--short] [-u|--uuid]

       pvscan [-d|--debug] [-h|--help] --cache [-a|--activate ay] [-b|--background] [--major major --minor minor
       | DevicePath | major:minor]...

DESCRIPTION

       pvscan scans all supported LVM block devices in the system for physical volumes.

   Scanning with lvmetad
       pvscan operates differently when used with the lvmetad(8) daemon.

       Scanning  disks  is  required  to  read LVM metadata and identify LVM PVs.  Once read, lvmetad caches the
       metadata so that LVM commands can read it without repeatedly scanning disks.   This  is  helpful  because
       scanning  disks is time consuming, and frequent scanning may interfere with the normal work of the system
       and disks.

       When lvmetad is not used, LVM commands revert to scanning disks to read metadata.  Any LVM  command  that
       needs  metadata will scan disks for it; running the pvscan command is not necessary for the sake of other
       LVM commands.

       When lvmetad is used, LVM commands avoid scanning disks by reading metadata from lvmetad.  When new disks
       appear,  they  must  be  scanned so their metadata can be cached in lvmetad.  This is done by the command
       pvscan --cache, which scans disks and passes the metadata to lvmetad.

       The pvscan --cache command is typically run automatically by system services when a new  device  appears.
       Users do not generally need to run this command if the system and lvmetad are running properly.

       Many scripts contain unnecessary pvscan (or vgscan) commands for historical reasons.  To avoid disrupting
       the system with extraneous disk scanning, an ordinary pvscan (without --cache) will simply read  metadata
       from lvmetad like other LVM commands.  It does not do anything beyond displaying the current state of the
       cache.

       Notes

       • When given specific device name arguments, pvscan --cache will only read the named devices.

       • LVM udev rules and systemd services are used to intiate automatic device scanning.

       • To prevent devices from being scanned by pvscan --cache, add them to lvm.conf(5) devices/global_filter.
         The devices/filter setting does not apply to system level scanning.  For more information, see:
         lvmconfig --withcomments devices/global_filter

       • If lvmetad is started or restarted after devices are visible, or if the global_filter has changed, then
         all devices must be rescanned for metadata with the command pvscan --cache.

       • lvmetad ignores older metadata formats, e.g. lvm1, and should not be used if they exist.

       • To notify lvmetad about a device that is no longer present, the major and minor numbers must be  given,
         not the path.

   Automatic activation
       When  event-driven  system  services detect a new LVM device, the first step is to automatically scan and
       cache the metadata from the device.  This is done by pvscan --cache.  A second step is  to  automatically
       activate LVs that are present on the new device.  This auto-activation is done by the same pvscan --cache
       command when the option '-a|--activate ay' is included.

       Auto-activation of VGs or LVs can be enabled/disabled using:
       lvm.conf(5) activation/auto_activation_volume_list

       For more information, see:
       lvmconfig --withcomments activation/auto_activation_volume_list

       When this setting is undefined, all LVs are auto-activated (when lvm is fully integrated with the  event-
       driven system services.)

       When a VG or LV is not auto-activated, traditional activation using vgchange or lvchange -a|--activate is
       needed.

       Notes

       • pvscan auto-activation can be only done in combination with --cache.

       • Auto-activation is designated by the "a" argument in '-a|--activate ay'.  This is meant to  distinguish
         system  generated  commands  from  explicit  user  commands,  although it can be used in any activation
         command.  Whenever it is used, the auto_activation_volume_list is applied.

       • Auto-activation is not yet supported for LVs that are part of partial or clustered volume groups.

OPTIONS

       See lvm(8) for common options.

       -e, --exported
              Only show physical volumes belonging to exported volume groups.

       -n, --novolumegroup
              Only show physical volumes not belonging to any volume group.

       -s, --short
              Short listing format.

       -u, --uuid
              Show UUIDs in addition to device names.

       -a, --activate ay
              Automatically activate any logical volumes that are possible to activate with the addition of  the
              new devices.

       -b, --background
              Run the command in the background.

       --cache [--major major --minor minor | DevicePath | major:minor ]...
              Scan one or more devices and send the metadata to lvmetad.

SEE ALSO

       lvm(8), lvmconfig(8), lvmetad(8)