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PVSCAN(8)                            System Manager's Manual                            PVSCAN(8)

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 inter‐
       fere 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 nec‐
       essary 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  scan‐
         ning.  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  automati‐
       cally  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 vol‐
         ume 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)

Sistina Software UK             LVM TOOLS 2.02.133(2) (2015-10-30)                      PVSCAN(8)

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