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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  [--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|--ver‐
       bose] SplitableLogicalVolume{Name|Path}

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

       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] [--thin‐
       pool  ThinPoolLogicalVolume{Name|Path}  [-c|--chunksize ChunkSize[bBsSkKmMgG]] [--discards
       {ignore|nopassdown|passdown}] [--poolmetadata  ThinPoolMetadataLogicalVolume{Name|Path}  |
       --poolmetadatasize    ThinPoolMetadataSize[bBsSkKmMgG]]   [-r|--readahead   {ReadAheadSec‐
       tors|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}] [--cachepol‐
       icy   policy]  [--cachesettings  key=value]  [--poolmetadata  CachePoolMetadataLogicalVol‐
       ume{Name|Path} | --poolmetadatasize  CachePoolMetadataSize[bBsSkKmMgG]]  [--poolmetadatas‐
       pare {y|n}] [--commandprofile ProfileName] [-h|-?|--help] [-v|--verbose] [--version] Logi‐
       calVolume{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 lvm‐
              cache(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  set‐
              tings.  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 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.

       --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 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.  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.   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" will be generated where  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 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 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 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 unmodi‐
              fied metadata are still available in "_meta" 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.

       --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 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 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)

Red Hat, Inc                    LVM TOOLS 2.02.133(2) (2015-10-30)                   LVCONVERT(8)

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