NAME¶
pvmove — move physical extents
SYNOPSIS¶
pvmove [
--abort] [
--alloc AllocationPolicy]
[
--atomic] [
-b|
--background] [
--commandprofile
ProfileName] [
-d|
--debug] [
-h|
--help]
[
-i|
--interval Seconds] [
--noudevsync]
[
-v|
--verbose] [
-n|
--name LogicalVolume]
[
SourcePhysicalVolume[
:PE[
-PE]...]
[
DestinationPhysicalVolume[
: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
LogicalVolume 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 SourcePhysicalVolumes, 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 movements required.
2. Every Logical Volume in the Volume Group is searched for contiguous data that
need moving 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 accessing 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 contains 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
volume. 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 volumes 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
or
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
SEE ALSO¶
lvm(8),
vgconvert(8) pvs(8)