lvconvert(8) — Linux manual page

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
           --cachedevice PV
           --cachemetadataformat auto|1|2
           --cachemode writethrough|writeback|passthrough
           --cachepolicy String
           --cachepool LV
           --cachesettings String
           --cachesize Size[m|UNIT]
           --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
           --raidintegrity y|n
           --raidintegrityblocksize Number
           --raidintegritymode String
        -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|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         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 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_thinpool_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 ]
       -

       Add a writecache to an LV, using a specified cache device.

       lvconvert --type writecache --cachedevice PV
       LV_linear_striped_raid
           [    --cachesize Size[m|UNIT] ]
           [    --cachesettings String ]
           [ COMMON_OPTIONS ]
       -

       Add a cache to an LV, using a specified cache device.

       lvconvert --type cache --cachedevice PV
       LV_linear_striped_thinpool_raid
           [ -c|--chunksize Size[k|UNIT] ]
           [    --cachesize Size[m|UNIT] ]
           [    --cachesettings 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 ... ]
       -

       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
           [    --cachesettings String ]
           [ 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 ]
       -

       Add or remove data integrity checksums to raid images.

       lvconvert --raidintegrity y|n LV_raid
           [    --raidintegritymode String ]
           [    --raidintegrityblocksize Number ]
           [ COMMON_OPTIONS ]
           [ PV ... ]
       -

       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         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.

       --cachedevice PV
              The name of a device to use for a cache.

       --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.

       --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.

       --cachesize Size[m|UNIT]
              The size of cache to use.

       --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 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.

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

       --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).

       --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
              lvmlockd(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
              --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.

       --nolocking
              Disable locking.

       --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'.

       --raidintegrity y|n
              Enable or disable data integrity checksums for raid
              images.

       --raidintegrityblocksize Number
              The block size to use for dm-integrity on raid images.
              The integrity block size should usually match the device
              logical block size, or the file system block size.  It may
              be less than the file system block size, but not less than
              the device logical block size.  Possible values: 512,
              1024, 2048, 4096.

       --raidintegritymode String
              Use a journal (default) or bitmap for keeping integrity
              checksums consistent in case of a crash. The bitmap areas
              are recalculated after a crash, so corruption in those
              areas would not be detected. A journal does not have this
              problem.  The journal mode doubles writes to storage, but
              can improve performance for scattered writes packed into a
              single journal write.  bitmap mode can in theory achieve
              full write throughput of the device, but would not benefit
              from the potential scattered write optimization.

       -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.  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 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 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|mirror|raid|thin|cache|vdo|thin-pool|cache-pool|vdo-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.  For VDO (vdo) see lvmvdo(7).
              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, --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 detail 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 information 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
              snapshot 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 creating 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         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 KiB, m|M is MiB, g|G is GiB, t|T is TiB,
              p|P is PiB, e|E is EiB.  (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.

       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_thinpool_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
           [    --cachesettings String ]
           [ 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         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) lvmpolld(8) lvmlockd(8) lvmlockctl(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, see ⟨https://github.com/lvmteam/lvm2/issues⟩.
       This page was obtained from the tarball
       https://github.com/lvmteam/lvm2/archive/refs/tags/v2_03_11.tar.gz
       fetched from ⟨https://github.com/lvmteam/lvm2/releases⟩ on
       2021-04-01.  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 2.03.11(2) (2021-01-08)       LVCONVERT(8)

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