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]    [--reportformat	  {basic|json}]	  [-s|--short]
       [-u|--uuid]

       pvscan [-d|--debug] [-h|--help] --cache [-a|--activate ay]  [-b|--back-
       ground]	[--reportformat	 {basic|json}]	[--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 his-
       torical reasons.	 To avoid disrupting the system with  extraneous  disk
       scanning,  an  ordinary pvscan (without --cache) will simply read meta-
       data from lvmetad like other LVM commands.  It  does  not  do  anything
       beyond displaying the current state of the cache.

       Notes


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


       o LVM udev rules and systemd services are used  to  initiate  automatic
	 device scanning.


       o 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


       o 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.


       o lvmetad does not cache older metadata formats, e.g. lvm1, and will be
	 temporarily disabled if they are seen.


       o 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|--acti-
       vate 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


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


       o 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.


       o 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)



Sistina Software UKLVM TOOLS 2.02.166(2)-RHEL7 (2016-11-16)	     PVSCAN(8)