Provided by: lvm2_2.03.16-2ubuntu1_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
           --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
           --devices PV
           --devicesfile String
           --discards passdown|nopassdown|ignore
           --driverloaded y|n
           --errorwhenfull y|n
        -f|--force
        -h|--help
        -i|--interval Number
           --journal String
           --lockopt String
           --longhelp
           --merge
           --mergemirrors
           --mergesnapshot
           --mergethin
           --metadataprofile String
           --mirrorlog core|disk
        -m|--mirrors [+|-]Number
        -n|--name String
           --nohints
           --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|raid|mirror|thin|thin-pool|vdo|vdo-pool|cache|
       cache-pool|writecache
           --uncache
           --usepolicies
           --vdopool LV
           --vdosettings String
        -v|--verbose
           --version
        -V|--virtualsize Size[m|UNIT]
        -y|--yes
        -Z|--zero y|n

DESCRIPTION

       lvconvert changes the LV type and includes utilities for LV data 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 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 LV1
           [ -i|--interval Number ]
           [ -R|--regionsize Size[m|UNIT] ]
           [ -I|--stripesize Size[k|UNIT] ]
           [ COMMON_OPTIONS ]
           [ PV ... ]

           LV1 types: raid

       —

       Convert raid LV to change the stripe size.

       lvconvert -I|--stripesize Size[k|UNIT] LV1
           [ -i|--interval Number ]
           [ -R|--regionsize Size[m|UNIT] ]
           [ COMMON_OPTIONS ]

           LV1 types: raid

       —

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

       lvconvert --splitmirrors Number -n|--name LV_new LV1
           [ COMMON_OPTIONS ]
           [ PV ... ]

           LV1 types: cache mirror raid1

       —

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

       lvconvert --splitmirrors Number --trackchanges LV1
           [ COMMON_OPTIONS ]
           [ PV ... ]

           LV1 types: cache raid1

       —

       Merge LV images that were split from a raid1 LV.

       lvconvert --mergemirrors VG|LV1|Tag ...
           [ COMMON_OPTIONS ]

           LV1 types: linear raid

       —

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

       lvconvert --type thin --thinpool LV LV1
           [ -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 ]

           LV1 types: linear striped thin cache raid error zero

       —

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

       lvconvert --type cache --cachepool LV LV1
           [ -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 ]

           LV1 types: linear striped thinpool vdo vdopool vdopooldata raid

       —

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

       lvconvert --type writecache --cachevol LV LV1
           [    --cachesettings String ]
           [ COMMON_OPTIONS ]

           LV1 types: linear striped thinpool raid

       —

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

       lvconvert --type cache --cachevol LV LV1
           [ -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 ]

           LV1 types: linear striped thinpool raid

       —

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

       lvconvert --type writecache --cachedevice PV LV1
           [    --cachesize Size[m|UNIT] ]
           [    --cachesettings String ]
           [ COMMON_OPTIONS ]

           LV1 types: linear striped thinpool raid

       —

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

       lvconvert --type cache --cachedevice PV LV1
           [ -c|--chunksize Size[k|UNIT] ]
           [    --cachesize Size[m|UNIT] ]
           [    --cachesettings String ]
           [ COMMON_OPTIONS ]

           LV1 types: linear striped thinpool raid

       —

       Convert LV to type thin-pool.

       lvconvert --type thin-pool LV1
           [ -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 ]
           [    --errorwhenfull y|n ]
           [    --poolmetadata LV ]
           [    --poolmetadatasize Size[m|UNIT] ]
           [    --poolmetadataspare y|n ]
           [    --metadataprofile String ]
           [ COMMON_OPTIONS ]
           [ PV ... ]

           LV1 types: linear striped cache raid error zero writecache

       —

       Convert LV to type cache-pool.

       lvconvert --type cache-pool LV1
           [ -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 ... ]

           LV1 types: linear striped raid

       —

       Convert LV to type vdopool.

       lvconvert --type vdo-pool LV1
           [ -n|--name LV_new ]
           [ -V|--virtualsize Size[m|UNIT] ]
           [ -r|--readahead auto|none|Number ]
           [ -Z|--zero y|n ]
           [    --metadataprofile String ]
           [    --compression y|n ]
           [    --deduplication y|n ]
           [    --vdosettings String ]
           [ COMMON_OPTIONS ]

           LV1 types: linear striped cache raid

       —

       Detach a cache from an LV.

       lvconvert --splitcache LV1
           [    --cachesettings String ]
           [ COMMON_OPTIONS ]

           LV1 types: thinpool cache cachepool vdopool writecache

       —

       Merge thin LV into its origin LV.

       lvconvert --mergethin LV1 ...
           [ COMMON_OPTIONS ]

           LV1 types: thin

       —

       Merge COW snapshot LV into its origin.

       lvconvert --mergesnapshot LV1 ...
           [ -i|--interval Number ]
           [ COMMON_OPTIONS ]

           LV1 types: snapshot

       —

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

       lvconvert --type snapshot LV LV1
           [ -s|--snapshot ]
           [ -c|--chunksize Size[k|UNIT] ]
           [ -Z|--zero y|n ]
           [ COMMON_OPTIONS ]

           LV1 types: linear striped

       —

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

       lvconvert --repair LV1
           [ -i|--interval Number ]
           [    --usepolicies ]
           [    --poolmetadataspare y|n ]
           [ COMMON_OPTIONS ]
           [ PV ... ]

           LV1 types: thinpool cache cachepool mirror raid

       —

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

       lvconvert --replace PV LV1
           [ COMMON_OPTIONS ]
           [ PV ... ]

           LV1 types: raid

       —

       Poll LV to continue conversion.

       lvconvert --startpoll LV1
           [ COMMON_OPTIONS ]

           LV1 types: mirror raid

       —

       Add or remove data integrity checksums to raid images.

       lvconvert --raidintegrity y|n LV1
           [    --raidintegritymode String ]
           [    --raidintegrityblocksize Number ]
           [ COMMON_OPTIONS ]
           [ PV ... ]

           LV1 types: raid

       —

       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 ]
           [    --devices PV ]
           [    --devicesfile String ]
           [    --driverloaded y|n ]
           [    --journal String ]
           [    --lockopt String ]
           [    --longhelp ]
           [    --nohints ]
           [    --nolocking ]
           [    --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 overridden 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 kernel options for dm-cache or dm-writecache LVs.  Use  the  form
              'option=value' or 'option1=value option2=value', or repeat --cachesettings for each
              option being set.  These settings override the default kernel behaviors  which  are
              usually  adequate.  To  remove  cachesettings  and  revert  to  the  default kernel
              behaviors,  use  --cachesettings  'default'  for  dm-cache  or  an   empty   string
              --cachesettings '' for dm-writecache.  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(5) settings.  The String
              arg uses the same format as lvm.conf(5), 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.

       --devices PV
              Restricts  the devices that are visible and accessible to the command.  Devices not
              listed will appear to be missing. This option can be repeated, or accepts  a  comma
              separated list of devices. This overrides the devices file.

       --devicesfile String
              A   file   listing   devices   that  LVM  should  use.   The  file  must  exist  in
              /etc/lvm/devices/ and is managed with the lvmdevices(8)  command.   This  overrides
              the lvm.conf(5) devices/devicesfile and devices/use_devicesfile settings.

       --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.

       --errorwhenfull y|n
              Specifies thin pool behavior when data space is exhausted.  When yes, device-mapper
              will immediately return an error when a thin  pool  is  full  and  an  I/O  request
              requires  space.  When no, device-mapper will queue these I/O requests for a period
              of time to allow the thin pool to be extended.  Errors are returned if no space  is
              available   after  the  timeout.   (Also  see  dm-thin-pool  kernel  module  option
              no_space_timeout.)  See lvmthin(7) for more information.

       -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.

       --journal String
              Record information in the systemd journal.  This  information  is  in  addition  to
              information   enabled   by  the  lvm.conf  log/journal  setting.   command:  record
              information about the command.  output: record the default command output.   debug:
              record full command debugging.

       --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(5)       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.

       --nohints
              Do not use the hints file to locate devices  for  PVs.  A  command  may  read  more
              devices  to  find  PVs  when  hints  are  not  used. The command will still perform
              standard hint file invalidation where appropriate.

       --nolocking
              Disable locking. Use  with  caution,  concurrent  commands  may  produce  incorrect
              results.

       --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(5)
              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|raid|mirror|thin|thin-pool|vdo|vdo-pool|cache|cache-pool|
              writecache
              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(5) or a
              profile.

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

       --vdosettings String
              Specifies tunable VDO  options  for  VDO  LVs.   Use  the  form  'option=value'  or
              'option1=value  option2=value',  or repeat --vdosettings for each option being set.
              These settings override the default  VDO  behaviors.   To  remove  vdosettings  and
              revert  to  the  default VDO behaviors, use --vdosettings 'default'.  See lvmvdo(7)
              for more information.

       -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(5)  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

       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.  LV1 indicates the  LV  must  have  a
              specific  type,  where  the  accepted LV types are listed. (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: 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

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

ADVANCED USAGE

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

       Change the region size of an LV.

       lvconvert -R|--regionsize Size[m|UNIT] LV1
           [ COMMON_OPTIONS ]

           LV1 types: raid

       —

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

       lvconvert --mirrorlog core|disk LV1
           [ COMMON_OPTIONS ]
           [ PV ... ]

           LV1 types: mirror

       —

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

       lvconvert -T|--thin --thinpool LV LV1
           [ --type thin ] (implied)
           [ -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 ]

           LV1 types: linear striped thin cache raid error zero

       —

       Attach a cache pool to an LV.

       lvconvert -H|--cache --cachepool LV LV1
           [ --type cache ] (implied)
           [ -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 ]

           LV1 types: linear striped thinpool vdo vdopool vdopooldata raid

       —

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

       lvconvert -H|--cache --cachevol LV LV1
           [ -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 ]

           LV1 types: linear striped thinpool raid

       —

       Convert LV to type vdopool.

       lvconvert --vdopool LV
           [ --type vdo-pool ] (implied)
           [ -r|--readahead auto|none|Number ]
           [ -Z|--zero y|n ]
           [ -n|--name LV_new ]
           [ -V|--virtualsize Size[m|UNIT] ]
           [    --metadataprofile String ]
           [    --compression y|n ]
           [    --deduplication y|n ]
           [    --vdosettings String ]
           [ COMMON_OPTIONS ]

       —

       Detach and delete a cache from an LV.

       lvconvert --uncache LV1
           [    --cachesettings String ]
           [ COMMON_OPTIONS ]

           LV1 types: thinpool cache vdopool writecache

       —

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

       lvconvert --swapmetadata --poolmetadata LV LV1
           [ -c|--chunksize Size[k|UNIT] ]
           [ COMMON_OPTIONS ]

           LV1 types: thinpool cachepool

       —

       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|LV1|Tag ...
           [ -i|--interval Number ]
           [ COMMON_OPTIONS ]

           LV1 types: linear striped snapshot thin raid

       —

       Separate a COW snapshot from its origin LV.

       lvconvert --splitsnapshot LV1
           [ COMMON_OPTIONS ]

           LV1 types: snapshot

       —

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

       lvconvert -s|--snapshot LV LV1
           [ --type snapshot ] (implied)
           [ -c|--chunksize Size[k|UNIT] ]
           [ -Z|--zero y|n ]
           [ COMMON_OPTIONS ]

           LV1 types: linear striped

       —

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

       lvconvert LV1
           [ COMMON_OPTIONS ]

           LV1 types: mirror raid

       —

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), lvmdevices(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), vgimportdevices(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), blkdeactivate(8), lvmdump(8),

       dmeventd(8), lvmpolld(8), lvmlockd(8), lvmlockctl(8), cmirrord(8), lvmdbusd(8), fsadm(8),

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