# lvconvert

## 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_
            **-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 inter‐
           changeably.
    
           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 recov‐
           ery  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 rea‐
           sons, 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). Addi‐
           tionally, 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. lin‐
           ear   ↔   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 ori‐
           gin.
    
           **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**]
               [ 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.  **nor‐**
                  **mal** 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 ex‐
                  isting PEs in the same stripe of the LV.  If there are suf‐
                  ficient PEs for an allocation,  but  normal  does  not  use
                  them,  **anywhere** will  use  them even if it reduces perfor‐
                  mance, e.g. by placing two stripes on the same PV.  Option‐
                  al 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  in‐
                  validates. 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 de‐
                  fault kernel values and removes them from the list of  set‐
                  tings stored in LVM metadata.  See lvmcache(7) for more in‐
                  formation.
    
           **--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 us‐
                  age.
    
           **--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_
                  Devices that the command can use. This option  can  be  re‐
                  peated  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)  **de‐**
                  **vices/devicesfile** and **devices/use_devicesfile** settings.
    
           **--discards passdown** |**nopassdown** |**ignore**
                  Specifies how the device-mapper thin pool layer in the ker‐
                  nel 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  informa‐
                  tion.
    
           **--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.  Er‐
                  rors are returned if no space is available after the  time‐
                  out.    (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 informa‐
                  tion 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.  de‐
                  bug: 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 --mergesnap‐
                  shot, 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  filesys‐
                  tem,  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 be‐
                  ing directed to the snapshot being merged. When  the  merge
                  finishes,  the  merged snapshot is removed.  Multiple snap‐
                  shots may be specified on the command line or a @tag may be
                  used to specify multiple snapshots be merged to  their  re‐
                  spective 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 per‐
                  sistent 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 im‐
                  ages of the data, the original and one mirror  image.   Op‐
                  tional  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_de‐
                  fault to configure the default types.  The  plus  prefix  **+**
                  can  be used, in which case the number is added to the cur‐
                  rent 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  de‐
                  fault  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 com‐
                  mand may read more devices to find PVs when hints  are  not
                  used. The command will still perform standard hint file in‐
                  validation where appropriate.
    
           **--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 be‐
                  comes 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, depend‐
                  ing 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  logi‐
                  cal  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 ar‐
                  eas 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 automat‐
                  ically.  **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 con‐
                  figure 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  un‐
                  used  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  mir‐
                  ror  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 speci‐
                  fied, then the images are permanently split from the origi‐
                  nal 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 never‐
                  theless 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  provision‐
                  ing.
    
           **--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 effi‐
                  ciently 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  perma‐
                  nently 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 perfor‐
                  mance (**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 un‐
                  used  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 informa‐
                  tion 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(5)  **global/sparse_segtype_default** determines
                  the default segment type used to create a sparse LV.   Any‐
                  thing  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  tar‐
                  get,  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 as‐
                  sume  the answer yes. Use with extreme caution.  (For auto‐
                  matic 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 repre‐
                  sents raid<N> type).
    
           _PV_     Physical Volume name, a device path under /dev.  For com‐
                  mands managing physical extents, a PV positional arg gener‐
                  ally 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.  In‐
                  put 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 ori‐
           gin.
    
           **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**]
               [ 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  --mergemir‐
           rors).
           Merge thin LV into its origin LV (variant, use --mergethin).
           Merge  COW  snapshot LV into its origin (variant, use --mergesnap‐
           shot).
    
           **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  opera‐
           tions:
           **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 a thick LV into a thin-pool data volume and continue using
           this LV through thinLV and for the conversion set the pool metada‐
           ta size to 1GiB.
           **lvconvert --type thin --poolmetadatasize 1G vg/lvol1**
    
           Convert an LV into a thin-pool with VDO deduplication and compres‐
           sion for storing its data.
           **lvconvert --type thin-pool --pooldatavdo y vg/lvol1**
    
           Convert an LV into a thin LV in the specified thin pool.  The  ex‐
           isting 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 ex‐
           isting 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**
    


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