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LVCONVERT(8) System Manager's Manual LVCONVERT(8)
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] [--type SegmentType]
[-A|--alloc AllocationPolicy] [-b|--background] [-f|--force]
[-i|--interval Seconds] [-h|-?|--help] [--stripes Stripes [-I|--stripe-
size StripeSize]] [--noudevsync] [-v|--verbose] [-y|--yes] [--version]
LogicalVolume[Path] [PhysicalVolume[Path][:PE[-PE]]...]
lvconvert --splitmirrors Images [--name SplitLogicalVolumeName]
[--trackchanges] MirrorLogicalVolume[Path] [SplittablePhysicalVol-
ume[Path][:PE[-PE]]...]
lvconvert -s|--snapshot [-c|--chunksize ChunkSize] [-h|-?|--help]
[--noudevsync] [-v|--verbose] [-Z|--zero {y|n}] [--version] Original-
LogicalVolume[Path] SnapshotLogicalVolume[Path]
lvconvert --merge [-b|--background] [-i|--interval Seconds]
[-h|-?|--help] [-v|--verbose] [--version] LogicalVolume[Path]...
lvconvert --thinpool ThinPoolLogicalVolume{Name|Path} [-c|--chunksize
ChunkSize] [-h|-?|--help] [-v|--verbose] [--version] [-Z|--zero {y|n}]
ThinMetadataLogicalVolume{Name|Path}
lvconvert --repair [-h|-?|--help] [-v|--verbose] [--version] Logi-
calVolume[Path] [PhysicalVolume[Path]...]
lvconvert --replace PhysicalVolume [-h|-?|--help] [-v|--verbose]
[--version] LogicalVolume[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(8) 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 --mir-
rorlog 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.
--type SegmentType
Used to convert a logical volume to another segment type or to
explicitly state the desired RAID1 segment type (mirror or
raid1) when converting a linear logical volume to a mirror with
the -m argument.
-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
4KiB and 512KiB.
-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(5),
viz. activation/mirror_log_fault_policy or activation/mir-
ror_device_fault_policy.
--replace PhysicalVolume
Remove the specified device (PhysicalVolume) and replace it with
one that is available in the volume group or from the specific
list provided. This option is only available to RAID segment
types (e.g. "raid1", "raid5", etc).
Examples
Converts the linear logical volume "vg00/lvol1" to a two-way mirror
logical volume:
lvconvert -m1 vg00/lvol1
Converts the linear logical volume "vg00/lvol1" to a two-way RAID1 log-
ical volume:
lvconvert --type raid1 -m1 vg00/lvol1
Converts a mirror with a disk log to a mirror with an in-memory log:
lvconvert --mirrorlog core vg00/lvol1
Converts a mirror with an in-memory log to a mirror with a disk log:
lvconvert --mirrorlog disk vg00/lvol1
Converts a mirror logical volume to a linear logical volume:
lvconvert -m0 vg00/lvol1
Converts a mirror logical volume to a RAID1 logical volume with the
same number of images:
lvconvert --type raid1 vg00/mirror_lv
Converts logical volume "vg00/lvol2" to snapshot of original volume
"vg00/lvol1":
lvconvert -s vg00/lvol1 vg00/lvol2
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 -m1 vg00/lvol1 /dev/sda:0-15 /dev/sdb:0-15
Converts mirror logical volume "vg00/lvmirror1" to linear, freeing
physical extents from /dev/sda:
lvconvert -m0 vg00/lvmirror1 /dev/sda
Merges "vg00/lvol1_snap" into its origin:
lvconvert --merge vg00/lvol1_snap
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 paral-
lel.
lvconvert --merge @some_tag
Extracts one image from the mirror, making it a new logical volume
named "lv_split". The mirror the image is extracted from is reduced
accordingly. If it was a 2-way mirror (created with '-m 1'), then the
resulting original volume will be linear.
lvconvert --splitmirrors 1 --name lv_split vg00/lvmirror1
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 separate 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_rimage_N, where N
is a number, and it cannot be renamed.
lvconvert --splitmirrors 1 --trackchanges vg00/lv_raid1
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.
lvconvert --merge vg00/lv_raid1_rimage_1
Replaces the physical volume "/dev/sdb1" in the RAID1 logical volume
"my_raid1" with the specified physical volume "/dev/sdf1". Had the
argument "/dev/sdf1" been left out, lvconvert would attempt to find a
suitable device from those available in the volume group.
lvconvert --replace /dev/sdb1 vg00/my_raid1 /dev/sdf1
SEE ALSO
lvm(8), vgcreate(8), lvremove(8), lvrename(8), lvextend(8), lvre-
duce(8), lvdisplay(8), lvscan(8)
Red Hat, Inc LVM TOOLS 2.02.98(2) (2012-10-15) LVCONVERT(8)
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