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lvconvert(8) - phpMan
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 [--type SegmentType] [--mirrorlog {disk|core|mirrored}]
[--corelog] [-R|--regionsize MirrorLogRegionSize] [--stripes Stripes [-I|--stripesize
StripeSize]] [-A|--alloc AllocationPolicy] [-b|--background] [-f|--force] [-i|--interval
Seconds] [--commandprofile ProfileName] [-h|-?|--help] [--noudevsync] [-v|--verbose]
[-y|--yes] [--version] LogicalVolume[Path] [PhysicalVolume[Path][:PE[-PE]]...]
lvconvert --splitmirrors Images [--name SplitLogicalVolumeName] [--trackchanges] Mirror‐
LogicalVolume[Path] [--commandprofile ProfileName] [SplittablePhysicalVol‐
ume[Path][:PE[-PE]]...]
lvconvert --splitsnapshot [--commandprofile ProfileName] [-h|-?|--help] [--noudevsync]
[-v|--verbose] [--version] SnapshotLogicalVolume[Path]
lvconvert -s|--snapshot [-c|--chunksize ChunkSize[bBsSkK]] [-Z|--zero {y|n}] [--command‐
profile ProfileName] [-h|-?|--help] [--noudevsync] [-v|--verbose] [--version] OriginalLog‐
icalVolume[Path] SnapshotLogicalVolume[Path]
lvconvert --merge [-b|--background] [-i|--interval Seconds] [--commandprofile ProfileName]
[-h|-?|--help] [-v|--verbose] [--version] LogicalVolume[Path]...
lvconvert --repair [--stripes Stripes [-I|--stripesize StripeSize]] [--commandprofile Pro‐
fileName] [-h|-?|--help] [-v|--verbose] [--version] LogicalVolume[Path] [PhysicalVol‐
ume[Path]...]
lvconvert --replace PhysicalVolume [--commandprofile ProfileName] [-h|-?|--help]
[-v|--verbose] [--version] LogicalVolume[Path] [PhysicalVolume[Path]...]
lvconvert [{--type thin[-pool]|-T|--thin} [--originname NewExternalOriginVolumeName]]
[--thinpool ThinPoolLogicalVolume{Name|Path} [-c|--chunksize ChunkSize[bBsSkKmMgG]]
[--discards {ignore|nopassdown|passdown}] [{--poolmetadata ThinPoolMetadataLogicalVol‐
ume{Name|Path} | --poolmetadatasize ThinPoolMetadataSize[bBsSkKmMgG]}] [-r|--readahead
{ReadAheadSectors|auto|none}] [--stripes Stripes [-I|--stripesize StripeSize]]] [--pool‐
metadataspare {y|n}] [-Z|--zero {y|n}]] [[ExternalOrigin|ThinPool]LogicalVol‐
ume{Name|Path}] [PhysicalVolume[Path][:PE [-PE]]...] [--commandprofile ProfileName]
[-h|-?|--help] [-v|--verbose] [--version]
lvconvert [--type cache[-pool]|--cache] [--cachepool CachePoolLV{Name|Path}] [-c|--chunk‐
size ChunkSize[bBsSkKmMgG]] [--cachemode {writeback|writethrough}] [{--poolmetadata
CachePoolMetadataLogicalVolume{Name|Path} | --poolmetadatasize CachePoolMetadata‐
Size[bBsSkKmMgG]}] [--poolmetadataspare {y|n}] LogicalVolume{Name|Path} [PhysicalVol‐
ume[Path][:PE[-PE]]...] [--commandprofile ProfileName] [-h|-?|--help] [-v|--verbose]
[--version]
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), allocation 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 specified PhysicalVolumes.
OPTIONS
See lvm(8) for common options.
Exactly one of --cache, --corelog, --merge, --mirrorlog, --mirrors, --repair, --replace,
--splitsnapshot, --snapshot, --splitmirrors, --thin or --type arguments is required.
-b, --background
Run the daemon in the background.
--cache, --type cache
Converts logical volume to a cached LV with the use of cache pool specified with
--cachepool. For more information on cache pool LVs and cache LVs, see lvm‐
cache(8).
--cachepool CachePoolLV
This argument is necessary when converting a logical volume to a cache LV. For
more information on cache pool LVs and cache LVs, see lvmcache(8).
-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. There are two implementations of mirroring which cor‐
respond to the "raid1" and "mirror" segment types. The default mirroring segment
type is "raid1". If the legacy "mirror" segment type is desired, the --type argu‐
ment must be used to explicitly select the desired type. The --mirrorlog and
--corelog options below are only relevant to the legacy "mirror" segment type.
--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 mir‐
ror is regenerated 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.
--type SegmentType
Used to convert a logical volume to another segment type, like cache, cache-pool,
raid1, snapshot, thin, or thin-pool. When converting a logical volume to a cache
LV, the --cachepool argument is required. When converting a logical volume to a
thin LV, the --thinpool argument is required. See lvmcache(7) for more info about
caching support and lvmthin(7) for thin provisioning support.
-i, --interval Seconds
Report progress as a percentage at regular intervals.
--noudevsync
Disables udev synchronisation. The process will not wait for notification from
udev. It will continue irrespective of any possible udev processing in the back‐
ground. 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 Name
The name to apply to a logical volume which has been split off from a mirror logi‐
cal 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 detached device where the data changed get resynchronized.
Please note that this feature is only supported with the new md-based mirror imple‐
mentation and not with the original device-mapper mirror implementation.
--splitsnapshot
Separates SnapshotLogicalVolume from its origin. The volume that is split off con‐
tains the chunks that differ from the origin along with the metadata describing
them. This volume can be wiped and then destroyed with lvremove. The inverse of
--snapshot.
-s, --snapshot, --type snapshot
Recreates a snapshot from constituent logical volumes (or copies of them) after
having been separated using --splitsnapshot. For this to work correctly, no
changes may be made to the contents of either volume after the split.
-c, --chunksize ChunkSize[bBsSkKmMgG]
Gives the size of chunk for snapshot, cache pool and thin pool logical volumes.
Default unit is in kilobytes.
For snapshots the value must be power of 2 between 4KiB and 512KiB and the default
value is 4.
For cache pools the value must be between 32KiB and 1GiB and the default value is
64.
For thin pools the value must be between 64KiB and 1GiB and the default value
starts with 64 and scales up to fit the pool metadata size within 128MiB, if the
pool metadata size is not specified. The value must be a multiple of 64KiB.
(Early kernel support until thin target version 1.4 required the value to be a
power of 2. Discards weren't supported for non-power of 2 values until thin target
version 1.5.)
--discards {ignore|nopassdown|passdown}
Specifies whether or not discards will be processed by the thin layer in the kernel
and passed down to the Physical Volume. Default is passdown.
-Z, --zero {y|n}
Controls zeroing of the first 4KiB of data in the snapshot. If the volume is read-
only the snapshot will not be zeroed. For thin pool volumes it controls zeroing of
provisioned blocks. Note: Provisioning of large zeroed chunks negatively impacts
performance.
--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. Merg‐
ing 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 snapshot being merged. When the merge finishes, the merged
snapshot is removed. Multiple snapshots may be specified on the commandline or a
@tag may be used to specify multiple snapshots be merged to their respective ori‐
gin.
--originname NewExternalOriginVolumeName
The new name for original logical volume, which becomes external origin volume for
a thin logical volume that will use given --thinpool.
Without this option a default name of "lvol<n>" will be generated where <n> is the
LVM internal number of the logical volume. This volume will be read-only and can‐
not be further modified as long, as it is being used as the external origin.
--poolmetadata ThinPoolMetadataLogicalVolume{Name|Path}
Specifies cache or thin pool metadata logical volume. The size should be in
between 2MiB and 16GiB. Cache pool is specified with the option --cachepool. Thin
pool is specified with the option --thinpool. When the specified pool already
exists, the pool's metadata volume will be swapped with the given LV. Pool proper‐
ties (like chunk size, discards or zero) are preserved by default in this case. It
can be useful for pool metadata repair or its offline resize, since the metadata
volume is available as regular volume for a user with thin provisioning tools
cache_dump(8), cache_repair(8), cache_restore(8), thin_dump(8), thin_repair(8) and
thin_restore(8).
--poolmetadatasize ThinPoolMetadataSize[bBsSkKmMgG]
Sets the size of thin pool's metadata logical volume, if the pool metadata volume
is undefined. Thin pool is specified with the option --thinpool. Supported value
is in the range between 2MiB and 16GiB. The default value is estimated with this
formula (Pool_LV_size / Pool_LV_chunk_size * 64b). Default unit is megabytes.
--poolmetadataspare {y|n}
Controls creation and maintanence of pool metadata spare logical volume that will
be used for automated pool recovery. Only one such volume is maintained within a
volume group with the size of the biggest pool metadata volume. Default is yes.
-r, --readahead {ReadAheadSectors|auto|none}
Sets read ahead sector count of thin pool metadata logical volume. The default
value is "auto" which allows the kernel to choose a suitable value automatically.
"None" is equivalent to specifying zero.
--repair
Repair a mirror after suffering a disk failure or try to fix thin pool metadata.
The mirror will be brought back into a consistent state. By default, the original
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/mirror_device_fault_policy.
Thin pool repair automates the use of thin_repair(8) tool. Only inactive thin pool
volumes can be repaired. There is no validation of metadata between kernel and
lvm2. This requires further manual work. After successfull repair the old unmodi‐
fied metadata are still available in "<pool>_meta<n>" LV.
--replace PhysicalVolume
Remove the specified device (PhysicalVolume) and replace it with one that is avail‐
able in the volume group or from the specific list provided. This option is only
available to RAID segment types (e.g. raid1, raid5, etc).
--stripes Stripes
Gives the number of stripes. This is equal to the number of physical volumes to
scatter the logical volume. This does not apply to existing allocated space, only
newly allocated space can be striped.
-I, --stripesize StripeSize
Gives the number of kilobytes for the granularity of the stripes.
StripeSize must be 2^n (n = 2 to 9) for metadata in LVM1 format. For metadata in
LVM2 format, the stripe size may be a larger power of 2 but must not exceed the
physical extent size.
-T, --thin, --type thin
Converts the logical volume into a thin logical volume of the thin pool specified
with --thinpool. The original logical volume ExternalOriginLogicalVolume is renamed
into a new read-only logical volume. For the non-default name for this volume use
--originname. The volume cannot be further modified as long as it is used as an
external origin volume for unprovisioned areas of any thin logical volume.
--thinpool ThinPoolLogicalVolume{Name|Path}
Specifies or converts logical volume into a thin pool's data volume. Content of
converted volume is lost. Thin pool's metadata logical volume can be specified
with the option --poolmetadata or allocated with --poolmetadatasize. See
lvmthin(7) for more info about thin provisioning support.
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 logical 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 snap‐
shot 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 --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 (cre‐
ated 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 argu‐
ment 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, lvcon‐
vert would attempt to find a suitable device from those available in the volume group.
lvconvert --replace /dev/sdb1 vg00/my_raid1 /dev/sdf1
Convert the logical volume "vg00/lvpool" into a thin pool with chunk size 128KiB and con‐
vert "vg00/lv1" into a thin volume using this pool. Original "vg00/lv1" is used as an
external read-only origin, where all writes to such volume are stored in the
"vg00/lvpool".
lvconvert --type thin --thinpool vg00/lvpool -c 128 lv1
Convert the logical volume "vg00/origin" into a thin volume from the thin pool
"vg00/lvpool". This thin volume will use "vg00/origin" as an external origin volume for
unprovisioned areas in this volume. For the read-only external origin use the new name
"vg00/external".
lvconvert -T --thinpool vg00/lvpool --originname external vg00/origin
Convert an existing logical volume to a cache pool LV using the given cache metadata LV.
lvconvert --type cache-pool --poolmetadata vg00/lvx_meta vg00/lvx_data
lvrename vg00/lvx_data vg00/lvx_cachepool
Convert an existing logical volume to a cache LV using the given cache pool LV.
lvconvert --cache --cachepool vg00/lvx_cachepool vg00/lvx
SEE ALSO
lvm(8), lvm.conf(5), lvmcache(7), lvmthin(7), lvdisplay(8), lvextend(8), lvreduce(8),
lvremove(8), lvrename(8), lvscan(8), vgcreate(8), cache_dump(8), cache_repair(8),
cache_restore(8), thin_dump(8), thin_repair(8), thin_restore(8)
Red Hat, Inc LVM TOOLS 2.02.111(2) (2014-09-01) LVCONVERT(8)
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