pvscan scans all supported LVM block devices in the system for
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
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.
· When given specific device name arguments, pvscan --cache will only
read the named devices.
· LVM udev rules and systemd services are used to initiate automatic
· 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,
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 does not cache older metadata formats, e.g. lvm1, and will
be temporarily disabled if they are seen.
· To notify lvmetad about a device that is no longer present, the
major and minor numbers must be given, not the path.
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:
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.
· pvscan auto-activation can be only done in combination with
· 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
· Auto-activation is not yet supported for LVs that are part of
partial or clustered volume groups.
See lvm(8) for common options.
Only show physical volumes belonging to exported volume
Only show physical volumes not belonging to any volume group.
Short listing format.
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.
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.
This page is part of the lvm2 (Logical Volume Manager 2) project.
Information about the project can be found at
⟨http://www.sourceware.org/lvm2/⟩. If you have a bug report for this
manual page, send it to firstname.lastname@example.org. This page was obtained
from the project's upstream Git repository
⟨https://git.fedorahosted.org/git/lvm2.git⟩ on 2017-03-13. If you
discover any rendering problems in this HTML version of the page, or
you believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
Sistina Software UKLVM TOOLS 2.02.169(2)-git (2016-11-30) PVSCAN(8)