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.