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LVCONVERT(8)                System Manager's Manual               LVCONVERT(8)

NAME
       lvconvert - Change logical volume layout

SYNOPSIS
       lvconvert option_args position_args
           [ option_args ]
           [ position_args ]

           --alloc contiguous|cling|cling_by_tags|normal|anywhere|inherit
        -b|--background
        -H|--cache
           --cachemetadataformat auto|1|2
           --cachemode writethrough|writeback|passthrough
           --cachepolicy String
           --cachepool LV
           --cachesettings String
           --cachevol LV
        -c|--chunksize Size[k|UNIT]
           --commandprofile String
           --compression y|n
           --config String
        -d|--debug
           --deduplication y|n
           --discards passdown|nopassdown|ignore
           --driverloaded y|n
        -f|--force
        -h|--help
        -i|--interval Number
           --lockopt String
           --longhelp
           --merge
           --mergemirrors
           --mergesnapshot
           --mergethin
           --metadataprofile String
           --mirrorlog core|disk
        -m|--mirrors [+|-]Number
        -n|--name String
           --nolocking
           --noudevsync
           --originname LV
           --poolmetadata LV
           --poolmetadatasize Size[m|UNIT]
           --poolmetadataspare y|n
           --profile String
        -q|--quiet
        -r|--readahead auto|none|Number
        -R|--regionsize Size[m|UNIT]
           --repair
           --replace PV
        -s|--snapshot
           --splitcache
           --splitmirrors Number
           --splitsnapshot
           --startpoll
           --stripes Number
        -I|--stripesize Size[k|UNIT]
           --swapmetadata
        -t|--test
        -T|--thin
           --thinpool LV
           --trackchanges
           --type linear|striped|snapshot|mir-
       ror|raid|thin|cache|vdo|thin-pool|cache-pool|vdo-pool
           --uncache
           --usepolicies
           --vdopool LV
        -v|--verbose
           --version
        -V|--virtualsize Size[m|UNIT]
        -y|--yes
        -Z|--zero y|n

DESCRIPTION
       lvconvert changes the LV type and includes utilities for LV data  main-
       tenance.  The LV type controls data layout and redundancy.  The LV type
       is also called the segment type or segtype.

       To display the current LV type, run the command:

       lvs -o name,segtype LV

       In some cases, an LV is a single device mapper (dm) layer above  physi-
       cal  devices.   In other cases, hidden LVs (dm devices) are layered be-
       tween the visible LV and physical devices.  LVs in  the  middle  layers
       are  called  sub LVs.  A command run on a visible LV sometimes operates
       on a sub LV rather than the specified LV.  In other  cases,  a  sub  LV
       must be specified directly on the command line.

       Sub LVs can be displayed with the command:

       lvs -a

       The  linear  type is equivalent to the striped type when one stripe ex-
       ists.  In that case, the types can sometimes be used interchangably.

       In most cases, the mirror type is deprecated and the raid1 type  should
       be used.  They are both implementations of mirroring.

       Striped raid types are raid0/raid0_meta, raid5 (an alias for raid5_ls),
       raid6 (an alias for raid6_zr) and raid10 (an alias for raid10_near).

       As opposed to mirroring, raid5 and raid6 stripe data and calculate par-
       ity  blocks.  The  parity blocks can be used for data block recovery in
       case devices fail. A maximum number of one device in  a  raid5  LV  may
       fail, and two in case of raid6. Striped raid types typically rotate the
       parity and data blocks for  performance  reasons,  thus  avoiding  con-
       tention  on  a  single device. Specific arrangements of parity and data
       blocks (layouts) can be used to optimize I/O performance, or to convert
       between raid levels.  See lvmraid(7) for more information.

       Layouts  of  raid5  rotating  parity  blocks  can  be:  left-asymmetric
       (raid5_la), left-symmetric (raid5_ls with alias raid5),  right-asymmet-
       ric  (raid5_ra),  right-symmetric (raid5_rs) and raid5_n, which doesn't
       rotate parity blocks. Layouts of raid6 are: zero-restart (raid6_zr with
       alias raid6), next-restart (raid6_nr), and next-continue (raid6_nc).

       Layouts  including _n allow for conversion between raid levels (raid5_n
       to raid6 or raid5_n to striped/raid0/raid0_meta). Additionally, special
       raid6  layouts  for raid level conversions between raid5 and raid6 are:
       raid6_ls_6, raid6_rs_6, raid6_la_6 and raid6_ra_6. Those correspond  to
       their  raid5  counterparts  (e.g. raid5_rs can be directly converted to
       raid6_rs_6 and vice-versa).

       raid10 (an alias for raid10_near) is currently limited to one data copy
       and  even number of sub LVs. This is a mirror group layout, thus a sin-
       gle sub LV may fail per mirror group without data loss.

       Striped raid types support converting the layout, their stripesize  and
       their number of stripes.

       The  striped  raid  types combined with raid1 allow for conversion from
       linear-> striped/raid0/raid0_meta and vice-versa  by  e.g.  linear  <->
       raid1 <-> raid5_n (then adding stripes) <-> striped/raid0/raid0_meta.

USAGE
       Convert LV to linear.

       lvconvert --type linear LV
           [ COMMON_OPTIONS ]
           [ PV ... ]
       -

       Convert LV to striped.

       lvconvert --type striped LV
           [ -I|--stripesize Size[k|UNIT] ]
           [ -R|--regionsize Size[m|UNIT] ]
           [ -i|--interval Number ]
           [    --stripes Number ]
           [ COMMON_OPTIONS ]
           [ PV ... ]
       -

       Convert LV to type mirror (also see type raid1),

       lvconvert --type mirror LV
           [ -m|--mirrors [+|-]Number ]
           [ -I|--stripesize Size[k|UNIT] ]
           [ -R|--regionsize Size[m|UNIT] ]
           [ -i|--interval Number ]
           [    --stripes Number ]
           [    --mirrorlog core|disk ]
           [ COMMON_OPTIONS ]
           [ PV ... ]
       -

       Convert LV to raid or change raid layout
       (a specific raid level must be used, e.g. raid1).

       lvconvert --type raid LV
           [ -m|--mirrors [+|-]Number ]
           [ -I|--stripesize Size[k|UNIT] ]
           [ -R|--regionsize Size[m|UNIT] ]
           [ -i|--interval Number ]
           [    --stripes Number ]
           [ COMMON_OPTIONS ]
           [ PV ... ]
       -

       Convert LV to raid1 or mirror, or change number of mirror images.

       lvconvert -m|--mirrors [+|-]Number LV
           [ -R|--regionsize Size[m|UNIT] ]
           [ -i|--interval Number ]
           [    --mirrorlog core|disk ]
           [ COMMON_OPTIONS ]
           [ PV ... ]
       -

       Convert raid LV to change number of stripe images.

       lvconvert --stripes Number LV_raid
           [ -i|--interval Number ]
           [ -R|--regionsize Size[m|UNIT] ]
           [ -I|--stripesize Size[k|UNIT] ]
           [ COMMON_OPTIONS ]
           [ PV ... ]
       -

       Convert raid LV to change the stripe size.

       lvconvert -I|--stripesize Size[k|UNIT] LV_raid
           [ -i|--interval Number ]
           [ -R|--regionsize Size[m|UNIT] ]
           [ COMMON_OPTIONS ]
       -

       Split images from a raid1 or mirror LV and use them to create a new LV.

       lvconvert --splitmirrors Number -n|--name LV_new LV_cache_mirror_raid1
           [ COMMON_OPTIONS ]
           [ PV ... ]
       -

       Split  images  from  a  raid1  LV and track changes to origin for later
       merge.

       lvconvert --splitmirrors Number --trackchanges LV_cache_raid1
           [ COMMON_OPTIONS ]
           [ PV ... ]
       -

       Merge LV images that were split from a raid1 LV.

       lvconvert --mergemirrors VG|LV_linear_raid|Tag ...
           [ COMMON_OPTIONS ]
       -

       Convert LV to a thin LV, using the original LV as an external origin.

       lvconvert --type thin --thinpool LV LV_linear_striped_thin_cache_raid
           [ -T|--thin ]
           [ -r|--readahead auto|none|Number ]
           [ -c|--chunksize Size[k|UNIT] ]
           [ -Z|--zero y|n ]
           [    --originname LV_new ]
           [    --poolmetadata LV ]
           [    --poolmetadatasize Size[m|UNIT] ]
           [    --poolmetadataspare y|n ]
           [    --metadataprofile String ]
           [ COMMON_OPTIONS ]
       -

       Attach a cache pool to an LV, converts the LV to type cache.

       lvconvert   --type   cache   --cachepool   LV   LV_linear_striped_thin-
       pool_vdo_vdopool_vdopooldata_raid
           [ -H|--cache ]
           [ -Z|--zero y|n ]
           [ -r|--readahead auto|none|Number ]
           [ -c|--chunksize Size[k|UNIT] ]
           [    --cachemetadataformat auto|1|2 ]
           [    --cachemode writethrough|writeback|passthrough ]
           [    --cachepolicy String ]
           [    --cachesettings String ]
           [    --poolmetadata LV ]
           [    --poolmetadatasize Size[m|UNIT] ]
           [    --poolmetadataspare y|n ]
           [    --metadataprofile String ]
           [ COMMON_OPTIONS ]
       -

       Attach a writecache to an LV, converts the LV to type writecache.

       lvconvert --type writecache --cachevol LV LV_linear_striped_raid
           [    --cachesettings String ]
           [ COMMON_OPTIONS ]
       -

       Attach a cache to an LV, converts the LV to type cache.

       lvconvert --type cache --cachevol LV LV_linear_striped_thinpool_raid
           [ -H|--cache ]
           [ -Z|--zero y|n ]
           [ -c|--chunksize Size[k|UNIT] ]
           [    --cachemetadataformat auto|1|2 ]
           [    --cachemode writethrough|writeback|passthrough ]
           [    --cachepolicy String ]
           [    --cachesettings String ]
           [    --poolmetadatasize Size[m|UNIT] ]
           [ COMMON_OPTIONS ]
       -

       Convert LV to type thin-pool.

       lvconvert --type thin-pool LV_linear_striped_cache_raid
           [ -I|--stripesize Size[k|UNIT] ]
           [ -r|--readahead auto|none|Number ]
           [ -c|--chunksize Size[k|UNIT] ]
           [ -Z|--zero y|n ]
           [    --stripes Number ]
           [    --discards passdown|nopassdown|ignore ]
           [    --poolmetadata LV ]
           [    --poolmetadatasize Size[m|UNIT] ]
           [    --poolmetadataspare y|n ]
           [    --metadataprofile String ]
           [ COMMON_OPTIONS ]
           [ PV ... ]
       -

       Convert LV to type cache-pool.

       lvconvert --type cache-pool LV_linear_striped_raid
           [ -Z|--zero y|n ]
           [ -r|--readahead auto|none|Number ]
           [ -c|--chunksize Size[k|UNIT] ]
           [    --cachemetadataformat auto|1|2 ]
           [    --cachemode writethrough|writeback|passthrough ]
           [    --cachepolicy String ]
           [    --cachesettings String ]
           [    --poolmetadata LV ]
           [    --poolmetadatasize Size[m|UNIT] ]
           [    --poolmetadataspare y|n ]
           [    --metadataprofile String ]
           [ COMMON_OPTIONS ]
           [ PV ... ]
       -

       Convert LV to type vdopool.

       lvconvert --type vdo-pool LV_linear_striped_cache_raid
           [ -n|--name LV_new ]
           [ -V|--virtualsize Size[m|UNIT] ]
           [    --compression y|n ]
           [    --deduplication y|n ]
           [ COMMON_OPTIONS ]
       -

       Detach a cache from an LV.

       lvconvert --splitcache LV_thinpool_cache_cachepool_vdopool_writecache
           [ COMMON_OPTIONS ]
       -

       Merge thin LV into its origin LV.

       lvconvert --mergethin LV_thin ...
           [ COMMON_OPTIONS ]
       -

       Merge COW snapshot LV into its origin.

       lvconvert --mergesnapshot LV_snapshot ...
           [ -i|--interval Number ]
           [ COMMON_OPTIONS ]
       -

       Combine a former COW snapshot (second arg) with a former
       origin LV (first arg) to reverse a splitsnapshot command.

       lvconvert --type snapshot LV LV_linear_striped
           [ -s|--snapshot ]
           [ -c|--chunksize Size[k|UNIT] ]
           [ -Z|--zero y|n ]
           [ COMMON_OPTIONS ]
       -

       Replace failed PVs in a raid or mirror LV.
       Repair a thin pool.
       Repair a cache pool.

       lvconvert --repair LV_thinpool_cache_cachepool_mirror_raid
           [ -i|--interval Number ]
           [    --usepolicies ]
           [    --poolmetadataspare y|n ]
           [ COMMON_OPTIONS ]
           [ PV ... ]
       -

       Replace specific PV(s) in a raid LV with another PV.

       lvconvert --replace PV LV_raid
           [ COMMON_OPTIONS ]
           [ PV ... ]
       -

       Poll LV to continue conversion.

       lvconvert --startpoll LV_mirror_raid
           [ COMMON_OPTIONS ]
       -

       Common options for command:
           [ -b|--background ]
           [ -f|--force ]
           [    --alloc contiguous|cling|cling_by_tags|normal|anywhere|inherit
           ]
           [    --noudevsync ]

       Common options for lvm:
           [ -d|--debug ]
           [ -h|--help ]
           [ -q|--quiet ]
           [ -t|--test ]
           [ -v|--verbose ]
           [ -y|--yes ]
           [    --commandprofile String ]
           [    --config String ]
           [    --driverloaded y|n ]
           [    --lockopt String ]
           [    --longhelp ]
           [    --nolocking ]
           [    --profile String ]
           [    --version ]

OPTIONS
       --alloc contiguous|cling|cling_by_tags|normal|anywhere|inherit
              Determines the allocation policy when a command needs to allo-
              cate Physical Extents (PEs) from the VG. Each VG and LV has an
              allocation policy which can be changed with vgchange/lvchange,
              or overriden on the command line.  normal applies common sense
              rules such as not placing parallel stripes on the same PV.  in-
              herit applies the VG policy to an LV.  contiguous requires new
              PEs be placed adjacent to existing PEs.  cling places new PEs on
              the same PV as existing PEs in the same stripe of the LV.  If
              there are sufficient PEs for an allocation, but normal does not
              use them, anywhere will use them even if it reduces performance,
              e.g. by placing two stripes on the same PV.  Optional positional
              PV args on the command line can also be used to limit which PVs
              the command will use for allocation.  See lvm(8) for more infor-
              mation about allocation.

       -b|--background
              If the operation requires polling, this option causes the com-
              mand to return before the operation is complete, and polling is
              done in the background.

       -H|--cache
              Specifies the command is handling a cache LV or cache pool.  See
              --type cache and --type cache-pool.  See lvmcache(7) for more
              information about LVM caching.

       --cachemetadataformat auto|1|2
              Specifies the cache metadata format used by cache target.

       --cachemode writethrough|writeback|passthrough
              Specifies when writes to a cache LV should be considered com-
              plete.  writeback considers a write complete as soon as it is
              stored in the cache pool.  writethough considers a write com-
              plete only when it has been stored in both the cache pool and on
              the origin LV.  While writethrough may be slower for writes, it
              is more resilient if something should happen to a device associ-
              ated with the cache pool LV. With passthrough, all reads are
              served from the origin LV (all reads miss the cache) and all
              writes are forwarded to the origin LV; additionally, write hits
              cause cache block invalidates. See lvmcache(7) for more informa-
              tion.

       --cachepolicy String
              Specifies the cache policy for a cache LV.  See lvmcache(7) for
              more information.

       --cachepool LV
              The name of a cache pool.

       --cachesettings String
              Specifies tunable values for a cache LV in "Key = Value" form.
              Repeat this option to specify multiple values.  (The default
              values should usually be adequate.)  The special string value
              default switches settings back to their default kernel values
              and removes them from the list of settings stored in LVM meta-
              data.  See lvmcache(7) for more information.

       --cachevol LV
              The name of a cache volume.

       -c|--chunksize Size[k|UNIT]
              The size of chunks in a snapshot, cache pool or thin pool.  For
              snapshots, the value must be a power of 2 between 4KiB and
              512KiB and the default value is 4.  For a cache pool the value
              must be between 32KiB and 1GiB and the default value is 64.  For
              a thin pool the value must be between 64KiB and 1GiB and the de-
              fault value starts with 64 and scales up to fit the pool meta-
              data size within 128MiB, if the pool metadata size is not speci-
              fied.  The value must be a multiple of 64KiB.  See lvmthin(7)
              and lvmcache(7) for more information.

       --commandprofile String
              The command profile to use for command configuration.  See
              lvm.conf(5) for more information about profiles.

       --compression y|n
              Controls whether compression is enabled or disable for VDO vol-
              ume.  See lvmvdo(7) for more information about VDO usage.

       --config String
              Config settings for the command. These override lvm.conf set-
              tings.  The String arg uses the same format as lvm.conf, or may
              use section/field syntax.  See lvm.conf(5) for more information
              about config.

       -d|--debug ...
              Set debug level. Repeat from 1 to 6 times to increase the detail
              of messages sent to the log file and/or syslog (if configured).

       --deduplication y|n
              Controls whether deduplication is enabled or disable for VDO
              volume.  See lvmvdo(7) for more information about VDO usage.

       --discards passdown|nopassdown|ignore
              Specifies how the device-mapper thin pool layer in the kernel
              should handle discards.  ignore causes the thin pool to ignore
              discards.  nopassdown causes the thin pool to process discards
              itself to allow reuse of unneeded extents in the thin pool.
              passdown causes the thin pool to process discards itself (like
              nopassdown) and pass the discards to the underlying device.  See
              lvmthin(7) for more information.

       --driverloaded y|n
              If set to no, the command will not attempt to use device-mapper.
              For testing and debugging.

       -f|--force ...
              Override various checks, confirmations and protections.  Use
              with extreme caution.

       -h|--help
              Display help text.

       -i|--interval Number
              Report progress at regular intervals.

       --lockopt String
              Used to pass options for special cases to lvmlockd.  See lvm-
              lockd(8) for more information.

       --longhelp
              Display long help text.

       --merge
              An alias for --mergethin, --mergemirrors, or --mergesnapshot,
              depending on the type of LV.

       --mergemirrors
              Merge LV images that were split from a raid1 LV.  See --split-
              mirrors with --trackchanges.

       --mergesnapshot
              Merge COW snapshot LV into its origin.  When merging a snapshot,
              if both the origin and snapshot LVs are not open, the merge will
              start immediately. Otherwise, the merge will start the first
              time either the origin or snapshot LV 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 result-
              ing LV will have the origin's name, minor number and UUID. While
              the merge is in progress, reads or writes to the origin appear
              as being directed to the snapshot 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.

       --mergethin
              Merge thin LV into its origin LV.  The origin thin LV takes the
              content of the thin snapshot, and the thin snapshot LV is re-
              moved.  See lvmthin(7) for more information.

       --metadataprofile String
              The metadata profile to use for command configuration.  See
              lvm.conf(5) for more information about profiles.

       --mirrorlog core|disk
              Specifies the type of mirror log for LVs with the "mirror" type
              (does not apply to the "raid1" type.)  disk is a persistent log
              and requires a small amount of storage space, usually on a sepa-
              rate device from the data being mirrored.  core is not persis-
              tent; the log is kept only in memory.  In this case, the mirror
              must be synchronized (by copying LV data from the first device
              to others) each time the LV is activated, e.g. after reboot.
              mirrored is a persistent log that is itself mirrored, but should
              be avoided. Instead, use the raid1 type for log redundancy.

       -m|--mirrors [+|-]Number
              Specifies the number of mirror images in addition to the origi-
              nal LV image, e.g. --mirrors 1 means there are two images of the
              data, the original and one mirror image.  Optional positional PV
              args on the command line can specify the devices the images
              should be placed on.  There are two mirroring implementations:
              "raid1" and "mirror".  These are the names of the corresponding
              LV types, or "segment types".  Use the --type option to specify
              which to use (raid1 is default, and mirror is legacy) Use
              lvm.conf global/mirror_segtype_default and global/raid10_seg-
              type_default to configure the default types.  The plus prefix +
              can be used, in which case the number is added to the current
              number of images, or the minus prefix - can be used, in which
              case the number is subtracted from the current number of images.
              See lvmraid(7) for more information.

       -n|--name String
              Specifies the name of a new LV.  When unspecified, a default
              name of "lvol#" is generated, where # is a number generated by
              LVM.

       --nolocking
              Disable locking.

       --noudevsync
              Disables udev synchronisation. The process will not wait for no-
              tification from udev. It will continue irrespective of any pos-
              sible udev processing in the background. Only use this if udev
              is not running or has rules that ignore the devices LVM creates.

       --originname LV
              Specifies the name to use for the external origin LV when con-
              verting an LV to a thin LV. The LV being converted becomes a
              read-only external origin with this name.

       --poolmetadata LV
              The name of a an LV to use for storing pool metadata.

       --poolmetadatasize Size[m|UNIT]
              Specifies the size of the new pool metadata LV.

       --poolmetadataspare y|n
              Enable or disable the automatic creation and management of a
              spare pool metadata LV in the VG. A spare metadata LV is re-
              served space that can be used when repairing a pool.

       --profile String
              An alias for --commandprofile or --metadataprofile, depending on
              the command.

       -q|--quiet ...
              Suppress output and log messages. Overrides --debug and --ver-
              bose.  Repeat once to also suppress any prompts with answer
              'no'.

       -r|--readahead auto|none|Number
              Sets read ahead sector count of an LV.  auto is the default
              which allows the kernel to choose a suitable value automati-
              cally.  none is equivalent to zero.

       -R|--regionsize Size[m|UNIT]
              Size of each raid or mirror synchronization region.  lvm.conf
              activation/raid_region_size can be used to configure a default.

       --repair
              Replace failed PVs in a raid or mirror LV, or run a repair util-
              ity on a thin pool. See lvmraid(7) and lvmthin(7) for more in-
              formation.

       --replace PV
              Replace a specific PV in a raid LV with another PV.  The new PV
              to use can be optionally specified after the LV.  Multiple PVs
              can be replaced by repeating this option.  See lvmraid(7) for
              more information.

       -s|--snapshot
              Combine a former COW snapshot LV with a former origin LV to re-
              verse a previous --splitsnapshot command.

       --splitcache
              Separates a cache pool from a cache LV, and keeps the unused
              cache pool LV.  Before the separation, the cache is flushed.
              Also see --uncache.

       --splitmirrors Number
              Splits the specified number of images from a raid1 or mirror LV
              and uses them to create a new LV. If --trackchanges is also
              specified, changes to the raid1 LV are tracked while the split
              LV remains detached.  If --name is specified, then the images
              are permanently split from the original LV and changes are not
              tracked.

       --splitsnapshot
              Separates a COW snapshot from its origin LV. The LV that is
              split off contains the chunks that differ from the origin LV
              along with metadata describing them. This LV can be wiped and
              then destroyed with lvremove.

       --startpoll
              Start polling an LV to continue processing a conversion.

       --stripes Number
              Specifies the number of stripes in a striped LV. This is the
              number of PVs (devices) that a striped LV is spread across. Data
              that appears sequential in the LV is spread across multiple de-
              vices in units of the stripe size (see --stripesize). This does
              not apply to existing allocated space, only newly allocated
              space can be striped.

       -I|--stripesize Size[k|UNIT]
              The amount of data that is written to one device before moving
              to the next in a striped LV.

       --swapmetadata
              Extracts the metadata LV from a pool and replaces it with an-
              other specified LV.  The extracted LV is preserved and given the
              name of the LV that replaced it.  Use for repair only. When the
              metadata LV is swapped out of the pool, it can be activated di-
              rectly and used with thin provisioning tools: cache_dump(8),
              cache_repair(8), cache_restore(8), thin_dump(8), thin_repair(8),
              thin_restore(8).

       -t|--test
              Run in test mode. Commands will not update metadata.  This is
              implemented by disabling all metadata writing but nevertheless
              returning success to the calling function. This may lead to un-
              usual error messages in multi-stage operations if a tool relies
              on reading back metadata it believes has changed but hasn't.

       -T|--thin
              Specifies the command is handling a thin LV or thin pool.  See
              --type thin, --type thin-pool, and --virtualsize.  See
              lvmthin(7) for more information about LVM thin provisioning.

       --thinpool LV
              The name of a thin pool LV.

       --trackchanges
              Can be used with --splitmirrors on a raid1 LV. This causes
              changes to the original raid1 LV to be tracked while the split
              images remain detached. This is a temporary state that allows
              the read-only detached image to be merged efficiently back into
              the raid1 LV later.  Only the regions with changed data are
              resynchronized during merge.  While a raid1 LV is tracking
              changes, operations on it are limited to merging the split image
              (see --mergemirrors) or permanently splitting the image (see
              --splitmirrors with --name.

       --type linear|striped|snapshot|mir-
              ror|raid|thin|cache|vdo|thin-pool|cache-pool|vdo-pool
              The LV type, also known as "segment type" or "segtype".  See us-
              age descriptions for the specific ways to use these types.  For
              more information about redundancy and performance (raid<N>, mir-
              ror, striped, linear) see lvmraid(7).  For thin provisioning
              (thin, thin-pool) see lvmthin(7).  For performance caching
              (cache, cache-pool) see lvmcache(7).  For copy-on-write snap-
              shots (snapshot) see usage definitions.  For VDO (vdo) see
              lvmvdo(7).  Several commands omit an explicit type option be-
              cause the type is inferred from other options or shortcuts (e.g.
              --stripes, --mirrors, --snapshot, --virtualsize, --thin,
              --cache, --vdo).  Use inferred types with care because it can
              lead to unexpected results.

       --uncache
              Separates a cache pool from a cache LV, and deletes the unused
              cache pool LV.  Before the separation, the cache is flushed.
              Also see --splitcache.

       --usepolicies
              Perform an operation according to the policy configured in
              lvm.conf or a profile.

       --vdopool LV
              The name of a VDO pool LV.  See lvmvdo(7) for more information
              about VDO usage.

       -v|--verbose ...
              Set verbose level. Repeat from 1 to 4 times to increase the de-
              tail of messages sent to stdout and stderr.

       --version
              Display version information.

       -V|--virtualsize Size[m|UNIT]
              The virtual size of a new thin LV.  See lvmthin(7) for more in-
              formation about LVM thin provisioning.  Using virtual size (-V)
              and actual size (-L) together creates a sparse LV.  lvm.conf
              global/sparse_segtype_default determines the default segment
              type used to create a sparse LV.  Anything written to a sparse
              LV will be returned when reading from it.  Reading from other
              areas of the LV will return blocks of zeros.  When using a snap-
              shot to create a sparse LV, a hidden virtual device is created
              using the zero target, and the LV has the suffix _vorigin.
              Snapshots are less efficient than thin provisioning when creat-
              ing large sparse LVs (GiB).

       -y|--yes
              Do not prompt for confirmation interactively but always assume
              the answer yes. Use with extreme caution.  (For automatic no,
              see -qq.)

       -Z|--zero y|n
              For snapshots, this controls zeroing of the first 4KiB of data
              in the snapshot. If the LV is read-only, the snapshot will not
              be zeroed.  For thin pools, this controls zeroing of provisioned
              blocks.  Provisioning of large zeroed chunks negatively impacts
              performance.

VARIABLES
       VG
              Volume Group name.  See lvm(8) for valid names.

       LV
              Logical  Volume  name.  See lvm(8) for valid names.  An LV posi-
              tional arg generally includes the VG  name  and  LV  name,  e.g.
              VG/LV.  LV followed by _<type> indicates that an LV of the given
              type is required. (raid represents raid<N> type)

       PV
              Physical Volume name, a device path under  /dev.   For  commands
              managing physical extents, a PV positional arg generally accepts
              a suffix indicating a range (or multiple ranges) of physical ex-
              tents  (PEs).  When  the first PE is omitted, it defaults to the
              start of the device, and when the last PE is omitted it defaults
              to  end.   Start and end range (inclusive): PV[:PE-PE]...  Start
              and length range (counting from 0): PV[:PE+PE]...

       Tag
              Tag name.  See lvm(8) for information about tag names and  using
              tags in place of a VG, LV or PV.

       String
              See the option description for information about the string con-
              tent.

       Size[UNIT]
              Size is an input number that accepts an  optional  unit.   Input
              units are always treated as base two values, regardless of capi-
              talization, e.g. 'k' and 'K' both refer to  1024.   The  default
              input unit is specified by letter, followed by |UNIT.  UNIT rep-
              resents other possible input units:  bBsSkKmMgGtTpPeE.   b|B  is
              bytes,  s|S  is  sectors  of 512 bytes, k|K is kilobytes, m|M is
              megabytes, g|G is gigabytes, t|T is terabytes, p|P is petabytes,
              e|E  is  exabytes.  (This should not be confused with the output
              control --units, where capital letters mean multiple of 1000.)

ENVIRONMENT VARIABLES
       See lvm(8) for information about environment  variables  used  by  lvm.
       For example, LVM_VG_NAME can generally be substituted for a required VG
       parameter.

ADVANCED USAGE
       Alternate command forms, advanced command usage,  and  listing  of  all
       valid syntax for completeness.

       Change the region size of an LV.

       lvconvert -R|--regionsize Size[m|UNIT] LV_raid
           [ COMMON_OPTIONS ]
       -

       Change the type of mirror log used by a mirror LV.

       lvconvert --mirrorlog core|disk LV_mirror
           [ COMMON_OPTIONS ]
           [ PV ... ]
       -

       Convert LV to a thin LV, using the original LV as an external origin
       (infers --type thin).

       lvconvert -T|--thin --thinpool LV LV_linear_striped_thin_cache_raid
           [ -r|--readahead auto|none|Number ]
           [ -c|--chunksize Size[k|UNIT] ]
           [ -Z|--zero y|n ]
           [    --type thin ]
           [    --originname LV_new ]
           [    --poolmetadata LV ]
           [    --poolmetadatasize Size[m|UNIT] ]
           [    --poolmetadataspare y|n ]
           [    --metadataprofile String ]
           [ COMMON_OPTIONS ]
       -

       Attach a cache pool to an LV (infers --type cache).

       lvconvert    -H|--cache    --cachepool    LV    LV_linear_striped_thin-
       pool_vdo_vdopool_vdopooldata_raid
           [ -Z|--zero y|n ]
           [ -r|--readahead auto|none|Number ]
           [ -c|--chunksize Size[k|UNIT] ]
           [    --type cache ]
           [    --cachemetadataformat auto|1|2 ]
           [    --cachemode writethrough|writeback|passthrough ]
           [    --cachepolicy String ]
           [    --cachesettings String ]
           [    --poolmetadata LV ]
           [    --poolmetadatasize Size[m|UNIT] ]
           [    --poolmetadataspare y|n ]
           [    --metadataprofile String ]
           [ COMMON_OPTIONS ]
       -

       Attach a cache to an LV, converts the LV to type cache.

       lvconvert -H|--cache --cachevol LV LV_linear_striped_thinpool_raid
           [ -Z|--zero y|n ]
           [ -c|--chunksize Size[k|UNIT] ]
           [    --cachemetadataformat auto|1|2 ]
           [    --cachemode writethrough|writeback|passthrough ]
           [    --cachepolicy String ]
           [    --cachesettings String ]
           [    --poolmetadatasize Size[m|UNIT] ]
           [ COMMON_OPTIONS ]
       -

       Convert LV to type vdopool.

       lvconvert --vdopool LV_linear_striped_cache_raid
           [ -n|--name LV_new ]
           [ -V|--virtualsize Size[m|UNIT] ]
           [    --type vdo-pool ]
           [    --compression y|n ]
           [    --deduplication y|n ]
           [ COMMON_OPTIONS ]
       -

       Detach and delete a cache from an LV.

       lvconvert --uncache LV_thinpool_cache_vdopool_writecache
           [ COMMON_OPTIONS ]
       -

       Swap metadata LV in a thin pool or cache pool (for repair only).

       lvconvert --swapmetadata --poolmetadata LV LV_thinpool_cachepool
           [ -c|--chunksize Size[k|UNIT] ]
           [ COMMON_OPTIONS ]
       -

       Merge LV that was split from a mirror (variant, use --mergemirrors).
       Merge thin LV into its origin LV (variant, use --mergethin).
       Merge COW snapshot LV into its origin (variant, use --mergesnapshot).

       lvconvert --merge VG|LV_linear_striped_snapshot_thin_raid|Tag ...
           [ -i|--interval Number ]
           [ COMMON_OPTIONS ]
       -

       Separate a COW snapshot from its origin LV.

       lvconvert --splitsnapshot LV_snapshot
           [ COMMON_OPTIONS ]
       -

       Combine a former COW snapshot (second arg) with a former
       origin LV (first arg) to reverse a splitsnapshot command.

       lvconvert -s|--snapshot LV LV_linear_striped
           [ -c|--chunksize Size[k|UNIT] ]
           [ -Z|--zero y|n ]
           [    --type snapshot ]
           [ COMMON_OPTIONS ]
       -

       Poll LV to continue conversion (also see --startpoll)
       or waits till conversion/mirror syncing is finished

       lvconvert LV_mirror_raid
           [ COMMON_OPTIONS ]
       -

NOTES
       This previous command syntax would perform two different operations:
       lvconvert --thinpool LV1 --poolmetadata LV2
       If LV1 was not a thin pool, the command would convert  LV1  to  a  thin
       pool,  optionally  using  a specified LV for metadata.  But, if LV1 was
       already a thin pool, the command would swap  the  current  metadata  LV
       with LV2 (for repair purposes.)

       In the same way, this previous command syntax would perform two differ-
       ent operations:
       lvconvert --cachepool LV1 --poolmetadata LV2
       If LV1 was not a cache pool, the command would convert LV1 to  a  cache
       pool,  optionally  using  a specified LV for metadata.  But, if LV1 was
       already a cache pool, the command would swap the  current  metadata  LV
       with LV2 (for repair purposes.)

EXAMPLES
       Convert a linear LV to a two-way mirror LV.
       lvconvert --type mirror --mirrors 1 vg/lvol1

       Convert a linear LV to a two-way RAID1 LV.
       lvconvert --type raid1 --mirrors 1 vg/lvol1

       Convert a mirror LV to use an in-memory log.
       lvconvert --mirrorlog core vg/lvol1

       Convert a mirror LV to use a disk log.
       lvconvert --mirrorlog disk vg/lvol1

       Convert a mirror or raid1 LV to a linear LV.
       lvconvert --type linear vg/lvol1

       Convert a mirror LV to a raid1 LV with the same number of images.
       lvconvert --type raid1 vg/lvol1

       Convert a linear LV to a two-way mirror LV, allocating new extents from
       specific PV ranges.
       lvconvert --mirrors 1 vg/lvol1 /dev/sda:0-15 /dev/sdb:0-15

       Convert a mirror LV to a linear LV, freeing  physical  extents  from  a
       specific PV.
       lvconvert --type linear vg/lvol1 /dev/sda

       Split one image from a mirror or raid1 LV, making it a new LV.
       lvconvert --splitmirrors 1 --name lv_split vg/lvol1

       Split one image from a raid1 LV, and track changes made to the raid1 LV
       while the split image remains detached.
       lvconvert --splitmirrors 1 --trackchanges vg/lvol1

       Merge an image (that was previously  created  with  --splitmirrors  and
       --trackchanges) back into the original raid1 LV.
       lvconvert --mergemirrors vg/lvol1_rimage_1

       Replace PV /dev/sdb1 with PV /dev/sdf1 in a raid1/4/5/6/10 LV.
       lvconvert --replace /dev/sdb1 vg/lvol1 /dev/sdf1

       Replace 3 PVs /dev/sd[b-d]1 with PVs /dev/sd[f-h]1 in a raid1 LV.
       lvconvert --replace /dev/sdb1 --replace /dev/sdc1 --replace /dev/sdd1
              vg/lvol1 /dev/sd[fgh]1

       Replace  the  maximum  of 2 PVs /dev/sd[bc]1 with PVs /dev/sd[gh]1 in a
       raid6 LV.
       lvconvert --replace /dev/sdb1 --replace /dev/sdc1 vg/lvol1 /dev/sd[gh]1

       Convert an LV into a thin LV in the specified thin pool.  The  existing
       LV is used as an external read-only origin for the new thin LV.
       lvconvert --type thin --thinpool vg/tpool1 vg/lvol1

       Convert  an LV into a thin LV in the specified thin pool.  The existing
       LV is used as an external read-only origin for the new thin LV, and  is
       renamed "external".
       lvconvert --type thin --thinpool vg/tpool1
              --originname external vg/lvol1

       Convert  an  LV to a cache pool LV using another specified LV for cache
       pool metadata.
       lvconvert --type cache-pool --poolmetadata vg/poolmeta1 vg/lvol1

       Convert an LV to a cache LV using the specified cache  pool  and  chunk
       size.
       lvconvert --type cache --cachepool vg/cpool1 -c 128 vg/lvol1

       Detach and keep the cache pool from a cache LV.
       lvconvert --splitcache vg/lvol1

       Detach and remove the cache pool from a cache LV.
       lvconvert --uncache vg/lvol1

SEE ALSO
       lvm(8) lvm.conf(5) lvmconfig(8)

       pvchange(8)  pvck(8)  pvcreate(8)  pvdisplay(8)  pvmove(8)  pvremove(8)
       pvresize(8) pvs(8) pvscan(8)

       vgcfgbackup(8) vgcfgrestore(8) vgchange(8) vgck(8)  vgcreate(8)  vgcon-
       vert(8)  vgdisplay(8)  vgexport(8)  vgextend(8)  vgimport(8)  vgimport-
       clone(8) vgmerge(8) vgmknodes(8)  vgreduce(8)  vgremove(8)  vgrename(8)
       vgs(8) vgscan(8) vgsplit(8)

       lvcreate(8)  lvchange(8)  lvconvert(8)  lvdisplay(8)  lvextend(8) lvre-
       duce(8) lvremove(8) lvrename(8) lvresize(8) lvs(8) lvscan(8)

       lvm-fullreport(8) lvm-lvpoll(8) lvm2-activation-generator(8) blkdeacti-
       vate(8) lvmdump(8)

       dmeventd(8)  lvmpolld(8)  lvmlockd(8)  lvmlockctl(8)  cmirrord(8) lvmd-
       busd(8)

       lvmsystemid(7) lvmreport(7) lvmraid(7) lvmthin(7) lvmcache(7)

Red Hat, Inc.          LVM TOOLS 2.03.07(2) (2019-11-30)          LVCONVERT(8)

NAME | SYNOPSIS | DESCRIPTION | USAGE | OPTIONS | VARIABLES | ENVIRONMENT VARIABLES | ADVANCED USAGE | NOTES | EXAMPLES | SEE ALSO