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

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

NAME         top

       lvconvert - Change logical volume layout

SYNOPSIS         top

       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         top

       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         top

       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 ]
       -

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

       lvconvert --repair LV_thinpool_mirror_raid
           [ -i|--interval Number ]
           [    --usepolicies ]
           [ 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         top

       --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         top

       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         top

       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         top

       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 --type snapshot LV LV_linear
           [ -s|--snapshot ]
           [ -c|--chunksize Size[k|UNIT] ]
           [ -Z|--zero y|n ]
           [ 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         top

       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         top

       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         top

       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)

COLOPHON         top

       This page is part of the lvm2 (Logical Volume Manager 2) project.
       Information about the project can be found at 
       ⟨http://www.sourceware.org/lvm2/⟩.  If you have a bug report for this
       manual page, send it to linux-lvm@redhat.com.  This page was obtained
       from the project's upstream Git repository 
       ⟨git://sourceware.org/git/lvm2.git⟩ on 2017-07-05.  If you discover
       any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page, or
       you have corrections or improvements to the information in this
       COLOPHON (which is not part of the original manual page), send a mail
       to man-pages@man7.org

Red Hat, Inc.      LVM TOOLS 2.02.173(2)-git (2017-06-28)       LVCONVERT(8)

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