Ubuntu Manpage: pvscan - List all physical volumes

Provided by: lvm2_2.02.176-4.1ubuntu3.18.04.3_amd64

NAME

       pvscan - List all physical volumes

SYNOPSIS

       pvscan option_args
           [ option_args ]
           [ position_args ]

DESCRIPTION

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

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.

• 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 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 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.

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 --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 --activate is
needed.

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

• Auto-activation is designated by the "a" argument in --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.

USAGE

       Display PV information.

       pvscan
           [ -e|--exported ]
           [ -n|--novolumegroup ]
           [ -s|--short ]
           [ -u|--uuid ]
           [ COMMON_OPTIONS ]

       Populate the lvmetad cache by scanning PVs.

       pvscan --cache
           [ -b|--background ]
           [ -a|--activate ay ]
           [ -j|--major Number ]
           [    --minor Number ]
           [ COMMON_OPTIONS ]
           [ String|PV ... ]

       Common options for command:
           [    --ignorelockingfailure ]
           [    --reportformat basic|json ]

       Common options for lvm:
           [ -d|--debug ]
           [ -h|--help ]
           [ -q|--quiet ]
           [ -t|--test ]
           [ -v|--verbose ]
           [ -y|--yes ]
           [    --commandprofile String ]
           [    --config String ]
           [    --driverloaded y|n ]
           [    --longhelp ]
           [    --profile String ]
           [    --version ]

OPTIONS

-a|--activate y|n|ay
Auto-activate LVs in a VG when the PVs scanned have completed the VG. (Only ay is applicable.)

-b|--background
If the operation requires polling, this option causes the command to return before the operation
is complete, and polling is done in the background.

--cache
Scan one or more devices and send the metadata to lvmetad.

--commandprofile String
The command profile to use for command configuration. See lvm.conf(5) for more information about
profiles.

--config String
Config settings for the command. These override lvm.conf settings. The String arg uses the same
format as lvm.conf, or may use section/field syntax. See lvm.conf(5) for more information about
config.

-d|--debug ...
Set debug level. Repeat from 1 to 6 times to increase the detail of messages sent to the log file
and/or syslog (if configured).

--driverloaded y|n
If set to no, the command will not attempt to use device-mapper. For testing and debugging.

-e|--exported
Only show PVs belonging to exported VGs.

-h|--help
Display help text.

--ignorelockingfailure
Allows a command to continue with read-only metadata operations after locking failures.

--longhelp
Display long help text.

-j|--major Number
The major number of a device.

--minor Number
The minor number of a device.

-n|--novolumegroup
Only show PVs not belonging to any VG.

--profile String
An alias for --commandprofile or --metadataprofile, depending on the command.

-q|--quiet ...
Suppress output and log messages. Overrides --debug and --verbose. Repeat once to also suppress
any prompts with answer 'no'.

--reportformat basic|json
Overrides current output format for reports which is defined globally by the report/output_format
setting in lvm.conf. basic is the original format with columns and rows. If there is more than
one report per command, each report is prefixed with the report name for identification. json
produces report output in JSON format. See lvmreport(7) for more information.

-s|--short
Short listing format.

-t|--test
Run in test mode. Commands will not update metadata. This is implemented by disabling all
metadata writing but nevertheless returning success to the calling function. This may lead to
unusual error messages in multi-stage operations if a tool relies on reading back metadata it
believes has changed but hasn't.

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

-v|--verbose ...
Set verbose level. Repeat from 1 to 4 times to increase the detail of messages sent to stdout and
stderr.

--version
Display version information.

-y|--yes
Do not prompt for confirmation interactively but always assume the answer yes. Use with extreme
caution. (For automatic no, see -qq.)

VARIABLES


       PV
              Physical  Volume  name,  a  device  path under /dev.  For commands managing physical extents, a PV
              positional arg generally accepts a suffix indicating a range  (or  multiple  ranges)  of  physical
              extents  (PEs). When the first PE is omitted, it defaults to the start of the device, and when the
              last PE is omitted it defaults to end.  Start and end range (inclusive): PV[:PE-PE]...  Start  and
              length range (counting from 0): PV[:PE+PE]...

       String
              See the option description for information about the string content.

       Size[UNIT]
              Size is an input number that accepts an optional unit.  Input units are always treated as base two
              values, regardless of capitalization, e.g. 'k' and 'K' both refer to 1024.  The default input unit
              is  specified  by  letter,  followed  by  |UNIT.   UNIT  represents  other  possible  input units:
              bBsSkKmMgGtTpPeE.  b|B is bytes, s|S is sectors of 512 bytes, k|K is kilobytes, m|M is  megabytes,
              g|G  is  gigabytes,  t|T  is  terabytes,  p|P  is petabytes, e|E is exabytes.  (This should not be
              confused with the output control --units, where capital letters mean multiple of 1000.)

ENVIRONMENT VARIABLES

       See lvm(8) for information about environment  variables  used  by  lvm.   For  example,  LVM_VG_NAME  can
       generally be substituted for a required VG parameter.