lvconvert(8) — Linux manual page

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

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

NAME         top

       lvconvert — Change logical volume layout

SYNOPSIS         top

       lvconvert option_args position_args
           [ option_args ]
           [ position_args ]

           --alloc contiguous|cling|cling_by_tags|normal|anywhere|
       inherit
        -b|--background
        -H|--cache
           --cachedevice PV
           --cachemetadataformat auto|1|2
           --cachemode writethrough|writeback|passthrough
           --cachepolicy String
           --cachepool LV
           --cachesettings String
           --cachesize Size[m|UNIT]
           --cachevol LV
        -c|--chunksize Size[k|UNIT]
           --commandprofile String
           --compression y|n
           --config String
        -d|--debug
           --deduplication y|n
           --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         top

       lvconvert  changes the LV type and includes utilities for LV data
       maintenance. The LV type controls  data  layout  and  redundancy.
       The LV type is also called the segment type or segtype.

       To display the current LV type, run the command:

       lvs -o name,segtype LV

       In  some  cases, an LV is a single device mapper (dm) layer above
       physical devices.  In other cases, hidden LVs  (dm  devices)  are
       layered  between the visible LV and physical devices.  LVs in the
       middle layers are called sub LVs.  A command run on a visible  LV
       sometimes  operates on a sub LV rather than the specified LV.  In
       other cases, a sub LV must be specified directly on  the  command
       line.

       Sub LVs can be displayed with the command:

       lvs -a

       The linear type is equivalent to the striped type when one stripe
       exists.   In  that  case,  the types can sometimes be used 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  calcu‐
       late  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 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  be‐
       tween 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 da‐
       ta copy and even number of sub LVs. This is a mirror  group  lay‐
       out,  thus a single sub LV may fail per mirror group without data
       loss.

       Striped raid types support converting the layout,  their  stripe‐
       size and their number of stripes.

       The  striped  raid types combined with raid1 allow for conversion
       from linear → striped/raid0/raid0_meta  and  vice-versa  by  e.g.
       linear    ↔   raid1   ↔   raid5_n   (then   adding   stripes)   ↔
       striped/raid0/raid0_meta.

USAGE         top

       Convert LV to linear.

       lvconvert --type linear LV
           [ COMMON_OPTIONS ]
           [ PV ... ]

       —

       Convert LV to striped.

       lvconvert --type striped LV
           [ -I|--stripesize Size[k|UNIT] ]
           [ -R|--regionsize Size[m|UNIT] ]
           [ -i|--interval Number ]
           [    --stripes Number ]
           [ COMMON_OPTIONS ]
           [ PV ... ]

       —

       Convert LV to type mirror (also see type raid1),

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

       —

       Convert LV to raid or change raid layout
       (a specific raid level must be used, e.g. raid1).

       lvconvert --type raid LV
           [ -m|--mirrors [+|-]Number ]
           [ -I|--stripesize Size[k|UNIT] ]
           [ -R|--regionsize Size[m|UNIT] ]
           [ -i|--interval Number ]
           [    --stripes Number ]
           [ COMMON_OPTIONS ]
           [ PV ... ]

       —

       Convert LV to raid1 or mirror, or change number of mirror images.

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

       —

       Convert raid LV to change number of stripe images.

       lvconvert --stripes Number 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 lat‐
       er 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 ]
           [ 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         top


       --alloc contiguous|cling|cling_by_tags|normal|anywhere|inherit
              Determines  the  allocation policy when a command needs to
              allocate Physical Extents (PEs) from the VG. Each  VG  and
              LV  has  an  allocation  policy  which can be changed with
              vgchange/lvchange, or  overridden  on  the  command  line.
              normal applies common sense rules such as not placing par‐
              allel stripes on the same PV.  inherit applies the VG pol‐
              icy to an LV.  contiguous requires new PEs be placed adja‐
              cent 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 per‐
              formance, e.g. by placing two stripes on the same PV.  Op‐
              tional positional PV args on the command line can also  be
              used  to  limit which PVs the command will use for alloca‐
              tion.  See lvm(8) for more information about allocation.

       -b|--background
              If the operation requires polling, this option causes  the
              command  to  return  before the operation is complete, and
              polling is done in the background.

       -H|--cache
              Specifies the command is handling  a  cache  LV  or  cache
              pool.   See  --type  cache  and  --type  cache-pool.   See
              lvmcache(7) for more information about LVM caching.

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

       --cachemetadataformat auto|1|2
              Specifies the cache metadata format used by cache  target.

       --cachemode writethrough|writeback|passthrough
              Specifies  when  writes to a cache LV should be considered
              complete.  writeback considers a write complete as soon as
              it is stored in the cache pool.  writethough  considers  a
              write  complete  only  when it has been stored in both the
              cache pool and on the origin LV.  While  writethrough  may
              be  slower  for  writes, it is more resilient if something
              should happen to a device associated with the  cache  pool
              LV. With passthrough, all reads are served from the origin
              LV (all reads miss the cache) and all writes are forwarded
              to  the  origin  LV;  additionally, write hits cause cache
              block invalidates. See lvmcache(7) for more information.

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

       --cachepool LV
              The name of a cache pool.

       --cachesettings String
              Specifies  tunable  values for a cache LV in "Key = Value"
              form.  Repeat this  option  to  specify  multiple  values.
              (The default values should usually be adequate.)  The spe‐
              cial  string value default switches settings back to their
              default kernel values and removes them from  the  list  of
              settings stored in LVM metadata.  See lvmcache(7) for more
              information.

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

       --cachevol LV
              The name of a cache volume.

       -c|--chunksize Size[k|UNIT]
              The size of chunks in a snapshot, cache pool or thin pool.
              For snapshots, the value must be a power of 2 between 4KiB
              and  512KiB  and the default value is 4.  For a cache pool
              the value must be between 32KiB and 1GiB and  the  default
              value  is  64.   For a thin pool the value must be between
              64KiB and 1GiB and the default value starts  with  64  and
              scales  up to fit the pool metadata size within 128MiB, if
              the pool metadata size is not specified.  The  value  must
              be  a  multiple  of 64KiB.  See lvmthin(7) and lvmcache(7)
              for more information.

       --commandprofile String
              The command profile to use for command configuration.  See
              lvm.conf(5) for more information about profiles.

       --compression y|n
              Controls whether compression is enabled or disable for VDO
              volume.  See lvmvdo(7) for more information about VDO  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
              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 ex‐
              tents 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  re‐
              quests  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  infor‐
              mation.

       -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.
              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  --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 snap‐
              shot LV are activated and both are closed. Merging a snap‐
              shot  into  an origin that cannot be closed, for example a
              root filesystem, is deferred until the next time the  ori‐
              gin  volume is activated. When merging starts, the result‐
              ing 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 com‐
              mand line or a @tag may be used to specify multiple  snap‐
              shots 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 snap‐
              shot 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.  In‐
              stead, 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 speci‐
              fy 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   glob‐
              al/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 in‐
              formation.

       -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
              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.

       --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,  de‐
              pending 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 im‐
              ages.

       --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 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  de‐
              fault  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 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 orig‐
              inal 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 ori‐
              gin 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 nev‐
              ertheless returning success to the calling function.  This
              may  lead  to unusual error messages in multi-stage opera‐
              tions if a tool relies on reading  back  metadata  it  be‐
              lieves 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 ef‐
              ficiently 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  lim‐
              ited  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 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
              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  infor‐
              mation 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 vir‐
              tual size (-V) and actual size  (-L)  together  creates  a
              sparse  LV.  lvm.conf(5) global/sparse_segtype_default de‐
              termines 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.  Snap‐
              shots are less efficient than thin provisioning when  cre‐
              ating large sparse LVs (GiB).

       -y|--yes
              Do  not  prompt  for confirmation interactively but always
              assume the answer yes. Use with extreme caution.  (For au‐
              tomatic no, see -qq.)

       -Z|--zero y|n
              For snapshots, this controls zeroing of the first 4KiB  of
              data in the snapshot. If the LV is read-only, the snapshot
              will not be zeroed.  For thin pools, this controls zeroing
              of  provisioned  blocks.   Provisioning  of  large  zeroed
              chunks negatively impacts performance.

VARIABLES         top

       VG     Volume Group name.  See lvm(8) for valid names.

       LV     Logical Volume name.  See lvm(8) for valid names.  An LV
              positional arg generally includes the VG name and LV name,
              e.g. VG/LV.  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 gen‐
              erally 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, regard‐
              less of capitalization, e.g. 'k' and 'K' both refer to
              1024.  The default input unit is specified by letter, fol‐
              lowed 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 con‐
              trol --units, where capital letters mean multiple of
              1000.)

ENVIRONMENT VARIABLES         top

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

ADVANCED USAGE         top

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

       Change the region size of an LV.

       lvconvert -R|--regionsize Size[m|UNIT] 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 ]
           [ 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         top

       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  cur‐
       rent metadata LV with LV2 (for repair purposes.)

EXAMPLES         top

       Convert a linear LV to a two-way mirror LV.
       lvconvert --type mirror --mirrors 1 vg/lvol1

       Convert a linear LV to a two-way RAID1 LV.
       lvconvert --type raid1 --mirrors 1 vg/lvol1

       Convert a mirror LV to use an in-memory log.
       lvconvert --mirrorlog core vg/lvol1

       Convert a mirror LV to use a disk log.
       lvconvert --mirrorlog disk vg/lvol1

       Convert a mirror or raid1 LV to a linear LV.
       lvconvert --type linear vg/lvol1

       Convert a mirror LV to a raid1 LV with the same number of images.
       lvconvert --type raid1 vg/lvol1

       Convert  a  linear  LV to a two-way mirror LV, allocating new ex‐
       tents 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 us‐
       ing this LV through thinLV and for the conversion  set  the  pool
       metadata size to 1GiB.
       lvconvert --type thin --poolmetadatasize 1G vg/lvol1

       Convert  an  LV  into a thin-pool with VDO deduplication and com‐
       pression 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

SEE ALSO         top

       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), lvmcache(7), lvmraid(7),
       lvmthin(7), lvmvdo(7), lvmautoactivation(7)

COLOPHON         top

       This page is part of the lvm2 (Logical Volume Manager 2) project.
       Information about the project can be found at 
       ⟨http://www.sourceware.org/lvm2/⟩.  If you have a bug report for
       this manual page, see ⟨https://github.com/lvmteam/lvm2/issues⟩.
       This page was obtained from the project's upstream Git repository
       ⟨git://sourceware.org/git/lvm2.git⟩ on 2024-06-14.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2024-06-11.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       [email protected]

Red Hat, Inc.     LVM TOOLS 2.03.25(2)-git (2024-05-16)     LVCONVERT(8)

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