NAME
lvconvert - convert a logical volume from linear to mirror or snapshot
SYNOPSIS
lvconvert -m|--mirrors Mirrors [--mirrorlog {disk|core|mirrored}]
[--corelog] [-R|--regionsize MirrorLogRegionSize] [-A|--alloc Alloca-
tionPolicy] [-b|--background] [-f|--force] [-i|--interval Seconds]
[-h|-?|--help] [--stripes Stripes [-I|--stripesize StripeSize]]
[--noudevsync] [-v|--verbose] [-y|--yes] [--version]
LogicalVolume[Path] [PhysicalVolume[Path][:PE[-PE]]...]
lvconvert --splitmirrors Images [--name SplitLogicalVolumeName]
[--trackchanges]
MirrorLogicalVolume[Path] [SplittablePhysicalVolume[Path][:PE[-PE]]...]
lvconvert -s|--snapshot [-c|--chunksize ChunkSize] [-h|-?|--help]
[--noudevsync] [-v|--verbose] [-Z|--zero y|n] [--version]
OriginalLogicalVolume[Path] SnapshotLogicalVolume[Path]
lvconvert --merge [-b|--background] [-i|--interval Seconds]
[-h|-?|--help] [-v|--verbose] [--version] LogicalVolume[Path]...
lvconvert --repair [-h|-?|--help] [-v|--verbose] [--version] Logi-
calVolume[Path] [PhysicalVolume[Path]...]
DESCRIPTION
lvconvert is used to change the segment type (i.e. linear, mirror, etc)
or characteristics of a logical volume. For example, it can add or
remove the redundant images of a logical volume, change the log type of
a mirror, or designate a logical volume as a snapshot repository.
If the conversion requires allocation of physical extents (for example,
when converting from linear to mirror) and you specify one or more
PhysicalVolumes (optionally with ranges of physical extents), alloca-
tion of physical extents will be restricted to these physical extents.
If the conversion frees physical extents (for example, when converting
from a mirror to a linear, or reducing mirror legs) and you specify one
or more PhysicalVolumes, the freed extents come first from the speci-
fied PhysicalVolumes.
OPTIONS
See lvm for common options.
Exactly one of --splitmirrors, --mirrors, --repair, --snapshot or
--merge arguments is required.
-m, --mirrors Mirrors
Specifies the degree of the mirror you wish to create. For
example, "-m 1" would convert the original logical volume to a
mirror volume with 2-sides; that is, a linear volume plus one
copy.
--mirrorlog {disk|core|mirrored}
Specifies the type of log to use. The default is disk, which is
persistent and requires a small amount of storage space, usually
on a separate device from the data being mirrored. Core may be
useful for short-lived mirrors: It means the mirror is regener-
ated by copying the data from the first device again every time
the device is activated - perhaps, for example, after every
reboot. Using "mirrored" will create a persistent log that is
itself mirrored.
--corelog
The optional argument "--corelog" is the same as specifying
"--mirrorlog core".
-R, --regionsize MirrorLogRegionSize
A mirror is divided into regions of this size (in MB), and the
mirror log uses this granularity to track which regions are in
sync.
-b, --background
Run the daemon in the background.
-i, --interval Seconds
Report progress as a percentage at regular intervals.
--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.
--splitmirrors Images
The number of redundant Images of a mirror to be split off and
used to form a new logical volume. A name must be supplied for
the newly-split-off logical volume using the --name argument,
unless the --trackchanges argument is given.
-n Name
The name to apply to a logical volume which has been split off
from a mirror logical volume.
--trackchanges
Used with --splitmirrors on a raid1 device, this tracks changes
so that the read-only detached image can be merged efficiently
back into the mirror later. Only the regions of the detatched
device where the data changed get resynchronized.
Please note that this feature is only supported with the new md-
based mirror implementation and not with the original device-
mapper mirror implementation.
-s, --snapshot
Create a snapshot from existing logical volume using another
existing logical volume as its origin.
-c, --chunksize ChunkSize
Power of 2 chunk size for the snapshot logical volume between 4k
and 512k.
-Z, --zero y|n
Controls zeroing of the first KB of data in the snapshot. If
the volume is read-only the snapshot will not be zeroed.
--merge
Merges a snapshot into its origin volume or merges a raid1 image
that has been split from its mirror with --trackchanges back
into its mirror.
To check if your kernel supports the snapshot merge feature,
look for 'snapshot-merge' in the output of 'dmsetup targets'.
If both the origin and snapshot volume are not open the merge
will start immediately. Otherwise, the merge will start the
first time either the origin or snapshot are activated and both
are closed. Merging a snapshot into an origin that cannot be
closed, for example a root filesystem, is deferred until the
next time the origin volume is activated. When merging starts,
the resulting logical volume will have the origin's name, minor
number and UUID. While the merge is in progress, reads or
writes to the origin appear as they were directed to the snap-
shot being merged. When the merge finishes, the merged snapshot
is removed. Multiple snapshots may be specified on the command-
line or a @tag may be used to specify multiple snapshots be
merged to their respective origin.
--repair
Repair a mirror after suffering a disk failure. The mirror will
be brought back into a consistent state. By default, the origi-
nal number of mirrors will be restored if possible. Specify -y
on the command line to skip the prompts. Use -f if you do not
want any replacement. Additionally, you may use --use-policies
to use the device replacement policy specified in lvm.conf, viz.
activation/mirror_log_fault_policy or activation/mir-
ror_device_fault_policy.
Examples
"lvconvert -m1 vg00/lvol1"
converts the linear logical volume "vg00/lvol1" to a two-way mirror
logical volume.
"lvconvert --mirrorlog core vg00/lvol1"
converts a mirror with a disk log to a mirror with an in-memory log.
"lvconvert --mirrorlog disk vg00/lvol1"
converts a mirror with an in-memory log to a mirror with a disk log.
"lvconvert -m0 vg00/lvol1"
converts a mirror logical volume to a linear logical volume.
"lvconvert -s vg00/lvol1 vg00/lvol2"
converts logical volume "vg00/lvol2" to snapshot of original volume
"vg00/lvol1"
"lvconvert -m1 vg00/lvol1 /dev/sda:0-15 /dev/sdb:0-15"
converts linear logical volume "vg00/lvol1" to a two-way mirror, using
physical extents /dev/sda:0-15 and /dev/sdb:0-15 for allocation of new
extents.
"lvconvert -m0 vg00/lvmirror1 /dev/sda"
converts mirror logical volume "vg00/lvmirror1" to linear, freeing
physical extents from /dev/sda.
"lvconvert --merge vg00/lvol1_snap"
merges "vg00/lvol1_snap" into its origin.
"lvconvert --merge @some_tag"
If vg00/lvol1, vg00/lvol2, and vg00/lvol3 are all tagged with
"some_tag" each snapshot logical volume will be merged serially, e.g.:
vg00/lvol1, then vg00/lvol2, then vg00/lvol3. If --background were
used it would start all snapshot logical volume merges in parallel.
"lvconvert --splitmirrors 1 --name lv_split vg00/lvmirror1"
Extract one image from the mirror, making it a new logical volume named
"lv_split". The mirror the image is extracted from is reduced accord-
ingly. If it was a 2-way mirror (created with '-m 1'), then the
resulting original volume will be linear.
"lvconvert --splitmirrors 1 --trackchanges vg00/lv_raid1"
A mirrored logical volume created with --type raid1 can use the
'--trackchanges' argument when splitting off an image.
Detach one image from the mirrored logical volume lv_raid1 as a sepa-
rate read-only device and track the changes made to the mirror while it
is detached. The split-off device has a name of the form lv_raid1_rim-
age_N, where N is a number, and it cannot be renamed.
"lvconvert --merge vg00/lv_raid1_rimage_1"
Merge an image that was detached temporarily from its mirror with the
'--trackchanges' argument back into its original mirror and bring its
contents back up-to-date.
SEE ALSO
lvm(8), vgcreate(8), lvremove(8), lvrename(8), lvextend(8), lvre-
duce(8), lvdisplay(8), lvscan(8)
Red Hat, Inc LVM TOOLS 2.02.88(2)-RHEL5 (2012-01-20) LVCONVERT(8)