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 --split [--commandprofile ProfileName] [-h|-?|--help] [--noudevsync] [-v|--verbose] SplitableLogicalVolume{Name|Path}

lvconvert --splitcache|--uncache [--commandprofile ProfileName] [-h|-?|--help] [--noudevsync] [-v|--verbose] [--version] CacheLogicalVolume{Name|Path}

lvconvert --splitmirrors Images [--name SplitLogicalVolumeName] [--trackchanges] MirrorLogicalVolume[Path] [--commandprofile ProfileName] [SplittablePhysicalVolume[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}] [--commandprofile ProfileName] [-h|-?|--help] [--noudevsync] [-v|--verbose] [--version] OriginalLogicalVolume[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 ProfileName] [-h|-?|--help] [-v|--verbose] [--version] LogicalVolume[Path] [PhysicalVolume[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 ThinPoolMetadataLogicalVolume{Name|Path} | --poolmetadatasize ThinPoolMetadataSize[bBsSkKmMgG]] [-r|--readahead {ReadAheadSectors|auto|none}] [--stripes Stripes [-I|--stripesize StripeSize]]] [--poolmetadataspare {y|n}] [-Z|--zero {y|n}]] [--commandprofile ProfileName] [-h|-?|--help] [-v|--verbose] [--version] [[ExternalOrigin|ThinPool]LogicalVolume{Name|Path}] [PhysicalVolume[Path][:PE [-PE]] ...

lvconvert --type cache[-pool]|-H|--cache [--cachepool CachePoolLogicalVolume{Name|Path}] [-c|--chunksize ChunkSize[bBsSkKmMgG]] [--cachemode {writeback|writethrough}] [--cachepolicy policy] [--cachesettings key=value] [--poolmetadata CachePoolMetadataLogicalVolume{Name|Path} | --poolmetadatasize CachePoolMetadataSize[bBsSkKmMgG]] [--poolmetadataspare {y|n}] [--commandprofile ProfileName] [-h|-?|--help] [-v|--verbose] [--version] LogicalVolume{Name|Path} [PhysicalVolume[Path][:PE[-PE]]...]

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, --snapshot, --split, --splitcache, --splitsnapshot, --splitmirrors, --thin, --type or --uncache arguments is required.

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

-H, --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 lvmcache(7).

--cachepolicy policy
    Only applicable to cached LVs; see also lvmcache(7). Sets the cache policy. mq is the basic policy name. smq is more advanced version available in newer kernels.

--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(7).

--cachesettings key=value
    Only applicable to cached LVs; see also lvmcache(7). Sets the cache tunable settings. In most use-cases, default values should be adequate. Special string value default switches setting back to its default kernel value and removes it from the list of settings stored in lvm2 metadata.

-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 correspond to the "raid1" and "mirror" segment types. The default mirroring segment type is "raid1". If the legacy "mirror" segment type is desired, the --type argument 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 mirror 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 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 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 detached 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.

--split
    Separates SplitableLogicalVolume. Option is agregating various split commands and tries to detect necessary split operation from its arguments.

--splitcache
    Separates CacheLogicalVolume from cache pool. Before the logical volume becomes uncached, cache is flushed. The cache pool volume is then left unused and could be used e.g. for caching another volume. See also the option --uncache for uncaching and removing cache pool with one command.

--splitsnapshot
    Separates SnapshotLogicalVolume from its origin. The volume that is split off contains 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. Options is currently supported only with thin pools. 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. 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 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 origin.

--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 cannot be further modified as long, as it is being used as the external origin.

--poolmetadata PoolMetadataLogicalVolume{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 properties (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 PoolMetadataSize[bBsSkKmMgG]
    Sets the size of cache or thin pool's metadata logical volume, if the pool metadata volume is undefined. Pool is specified with the option --cachepool or --thinpool. For thin pool 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 unmodified metadata are still available in "<pool>_meta<n>" LV.

--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).

--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.

--uncache
    Uncaches CacheLogicalVolume. Before the volume becomes uncached, cache is flushed. Unlike with --splitcache the cache pool volume is removed. This option could be seen as an inverse of --cache.

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 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 --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

Convert the logical volume "vg00/lvpool" into a thin pool with chunk size 128KiB and convert "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 and chunk size 128KiB.

lvconvert --cache --cachepool vg00/lvx_cachepool -c 128 vg00/lvx

Detach cache pool from an existing cached logical volume "vg00/lvol1" and leave cache pool unused.

lvconvert --splitcache vg00/lvol1

Drop cache pool from an existing cached logical volume "vg00/lvol1".

lvconvert --uncache vg00/lvol1

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)