Provided by: lvm2_2.02.176-4.1ubuntu3_amd64 bug

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
        -c|--chunksize Size[k|UNIT]
           --commandprofile String
           --config String
        -d|--debug
           --discards passdown|nopassdown|ignore
           --driverloaded y|n
        -f|--force
        -h|--help
        -i|--interval Number
           --longhelp
           --merge
           --mergemirrors
           --mergesnapshot
           --mergethin
           --metadataprofile String
           --mirrorlog core|disk
        -m|--mirrors [+|-]Number
        -n|--name String
           --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|mirror|raid|thin|cache|thin-pool|cache-pool
           --uncache
           --usepolicies
        -v|--verbose
           --version
        -y|--yes
        -Z|--zero y|n

DESCRIPTION

       lvconvert  changes the LV type and includes utilities for LV data maintenance. 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 physical devices.  In
       other cases, hidden LVs (dm devices) are layered  between  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 exists.  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  parity  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
       contention 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-asymmetric (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 single 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 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.

       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_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 ]
       -

       Convert LV to type cache.

       lvconvert --type cache --cachepool LV LV_linear_striped_thinpool_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 ]
       -

       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 ... ]
       -

       Separate and keep the cache pool from a cache LV.

       lvconvert --splitcache LV_thinpool_cache_cachepool
           [ 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
           [ -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 ]
           [    --longhelp ]
           [    --profile String ]
           [    --version ]

OPTIONS

       --alloc contiguous|cling|cling_by_tags|normal|anywhere|inherit
              Determines the allocation policy when a command needs to allocate 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.  inherit 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
              information about allocation.

       -b|--background
              If the operation requires polling, this option causes the command 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 complete.  writeback
              considers a write complete as soon as it is stored in the cache pool.  writethough
              considers a write complete 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 associated 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 information.

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

       --cachepool LV
              The name of a cache pool LV.

       --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 metadata.  See lvmcache(7)
              for more information.

       -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 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.  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.

       --config String
              Config settings for the command. These override lvm.conf settings.  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).

       --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.

       --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 --splitmirrors 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 resulting 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 removed.  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 separate device from the data being mirrored.  core is not
              persistent; 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 original 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_segtype_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.

       --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. 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 converting 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 reserved 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 --verbose.  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 automatically.  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 utility on a thin pool.
              See lvmraid(7) and lvmthin(7) for more information.

       --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 reverse 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.

       --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 devices 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 another 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 directly 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 unusual 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 allows the
              read-only detached image(s) to be merged efficiently back into the raid1 LV later.
              Only the regions with changed data are resynchronized during merge. (This option
              only applies when using the raid1 LV type.)

       --type linear|striped|snapshot|mirror|raid|thin|cache|thin-pool|cache-pool
              The LV type, also known as "segment type" or "segtype".  See usage descriptions for
              the specific ways to use these types.  For more information about redundancy and
              performance (raid<N>, mirror, 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 snapshots (snapshot) see usage
              definitions.  Several commands omit an explicit type option because the type is
              inferred from other options or shortcuts (e.g. --stripes, --mirrors, --snapshot,
              --virtualsize, --thin, --cache).  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.

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

       --version
              Display version information.

       -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 positional 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  extents  (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 content.

       Size[UNIT]
              Size  is  an  input  number  that accepts an optional unit.  Input units are always
              treated as base two values, regardless of capitalization, e.g.  'k'  and  'K'  both
              refer  to  1024.  The default input unit is specified by letter, followed by |UNIT.
              UNIT represents 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.

       Convert LV to type mirror (also see type raid1),
       (also see lvconvert --mirrors).

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

       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_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 ]
       -

       Convert LV to type cache (infers --type cache).

       lvconvert -H|--cache --cachepool LV LV_linear_striped_thinpool_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 ]
       -

       Separate and delete the cache pool from a cache LV.

       lvconvert --uncache LV_thinpool_cache
           [ 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
           [ -c|--chunksize Size[k|UNIT] ]
           [ -Z|--zero y|n ]
           [    --type snapshot ]
           [ COMMON_OPTIONS ]
       -

       Poll LV to continue conversion (also see --startpoll).

       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 different 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) vgconvert(8) vgdisplay(8)
       vgexport(8) vgextend(8) vgimport(8) vgimportclone(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)  lvreduce(8) lvremove(8)
       lvrename(8) lvresize(8) lvs(8) lvscan(8)

       lvm-fullreport(8) lvm-lvpoll(8) lvm2-activation-generator(8) blkdeactivate(8) lvmdump(8)

       dmeventd(8)  lvmetad(8)  lvmpolld(8)  lvmlockd(8)   lvmlockctl(8)   clvmd(8)   cmirrord(8)
       lvmdbusd(8)

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