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

NAME
pvmove — move physical extents

SYNOPSIS
pvmove [--abort] [--alloc AllocationPolicy] [--atomic] [-b|--background] [--commandprofile
ProfileName] [-d|--debug] [-h|--help] [-i|--interval Seconds] [--noudevsync] [-v|--ver‐
bose] [-n|--name LogicalVolume] [SourcePhysicalVolume[:PE[-PE]...] [DestinationPhysi‐
calVolume[:PE[-PE]...]...]]

DESCRIPTION
pvmove allows you to move the allocated physical extents (PEs) on SourcePhysicalVolume to
one or more other physical volumes (PVs). You can optionally specify a source LogicalVol‐
ume in which case only extents used by that LV will be moved to free (or specified)
extents on DestinationPhysicalVolume(s). If no DestinationPhysicalVolume is specified,
the normal allocation rules for the Volume Group are used.

If pvmove gets interrupted for any reason (e.g. the machine crashes) then run pvmove again
without any PhysicalVolume arguments to restart any moves that were in progress from the
last checkpoint. Alternatively use pvmove --abort at any time to abort. The resulting
location of logical volumes after an abort is issued depends on whether the --atomic
option was used when starting the pvmove process.

You can run more than one pvmove at once provided they are moving data off different Sour‐
cePhysicalVolumes, but additional pvmoves will ignore any Logical Volumes already in the
process of being changed, so some data might not get moved.

pvmove works as follows:

1. A temporary 'pvmove' Logical Volume is created to store details of all the data move‐
ments required.

2. Every Logical Volume in the Volume Group is searched for contiguous data that need mov‐
ing according to the command line arguments. For each piece of data found, a new segment
is added to the end of the pvmove LV. This segment takes the form of a temporary mirror
to copy the data from the original location to a newly-allocated location. The original
LV is updated to use the new temporary mirror segment in the pvmove LV instead of access‐
ing the data directly.

3. The Volume Group metadata is updated on disk.

4. The first segment of the pvmove Logical Volume is activated and starts to mirror the
first part of the data. Only one segment is mirrored at once as this is usually more
efficient.

5. A daemon repeatedly checks progress at the specified time interval. When it detects
that the first temporary mirror is in-sync, it breaks that mirror so that only the new
location for that data gets used and writes a checkpoint into the Volume Group metadata on
disk. Then it activates the mirror for the next segment of the pvmove LV.

6. When there are no more segments left to be mirrored, the temporary Logical Volume is
removed and the Volume Group metadata is updated so that the Logical Volumes reflect the
new data locations.

Note that this new process cannot support the original LVM1 type of on-disk metadata.
Metadata can be converted using vgconvert(8).

If the --atomic option is used, a slightly different approach is used for the move.
Again, a temporary 'pvmove' logical volume is created to store the details of all the data
movements required. This temporary LV contains all the segments of the various LVs that
need to be moved. However this time, an identical logical volume is allocated that con‐
tains the same number of segments and a mirror is created to copy the contents from the
first temporary LV to the second. When a complete copy is accomplished, the temporary
logical volumes are removed, leaving behind the segments on the destination physical vol‐
ume. If an abort is issued during the move, all logical volumes being moved will remain
on the source physical volume.

OPTIONS
See lvm(8) for common options.

--abort
Abort any moves in progress. If the --atomic option was used to start the pvmove,
all logical volumes will remain on the source physical volume. Otherwise, those
segments that have completed the move will stay on the destination physical volume,
while those that have not will remain on the source physical volume.

--atomic
Make the entire operation atomic. That is, ensure that all affected logical vol‐
umes are moved to the destination physical volume together; unless the move has
been aborted. If the move has been aborted, all logical volumes will remain on the
source physical volume.

--noudevsync
Disable udev synchronisation. The process will not wait for notification from udev.
It will continue irrespective of any possible udev processing in the background.
You should only use this if udev is not running or has rules that ignore the
devices LVM2 creates.

-b, --background
Run the daemon in the background.

-i, --interval Seconds
Report progress as a percentage at regular intervals.

-n, --name LogicalVolume
Move only the extents belonging to LogicalVolume from SourcePhysicalVolume instead
of all allocated extents to the destination physical volume(s).

Examples
To move all Physical Extents that are used by simple Logical Volumes on /dev/sdb1 to free
Physical Extents elsewhere in the Volume Group use:

pvmove /dev/sdb1

Additionally, a specific destination device /dev/sdc1 can be specified like this:

pvmove /dev/sdb1 /dev/sdc1

To perform the action only on extents belonging to the single Logical Volume lvol1 do
this:

pvmove -n lvol1 /dev/sdb1 /dev/sdc1

Rather than moving the contents of the entire device, it is possible to move a range of
Physical Extents - for example numbers 1000 to 1999 inclusive on /dev/sdb1 - like this:

pvmove /dev/sdb1:1000-1999

A range can also be specified as start+length, so

pvmove /dev/sdb1:1000+1000

also refers to 1000 Physical Extents starting from Physical Extent number 1000. (Counting
starts from 0, so this refers to the 1001st to the 2000th inclusive.)

To move a range of Physical Extents to a specific location (which must have sufficient
free extents) use the form:

pvmove /dev/sdb1:1000-1999 /dev/sdc1

pvmove /dev/sdb1:1000-1999 /dev/sdc1:0-999

If the source and destination are on the same disk, the anywhere allocation policy would
be needed, like this:

pvmove --alloc anywhere /dev/sdb1:1000-1999 /dev/sdb1:0-999

The part of a specific Logical Volume present within in a range of Physical Extents can
also be picked out and moved, like this:

pvmove -n lvol1 /dev/sdb1:1000-1999 /dev/sdc1