.TH LVCONVERT 8 "LVM TOOLS #VERSION#" "Red Hat, Inc" \" -*- nroff -*-
.SH NAME
lvconvert \(em change LV type and other utilities
.
.SH SYNOPSIS

.B lvconvert
.RI [ OPTION ]...
.IR VolumeGroup / LogicalVolume

OPTIONS:
.br
.BR \-b ,
.BR \-\-background
.br
.BR \-\-cachepolicy
.IR Policy
.br
.BR \-\-cachepool
.IR CachePoolLogicalVolume { Name | Path }
.br
.BR \-\-cachesettings
.IB Key = Value
.br
.BR \-c ,
.BR \-\-chunksize
.BR \fIChunkSize [ b | B | s | S | k | K | m | M | g | G ]
.br
.BR \-\-corelog
.br
.BR \-\-discards
.RB { ignore | nopassdown | passdown }
.br
.BR \-i ,
.BR \-\-interval
.IR Seconds
.br
.BR \-\-merge
.br
.BR \-\-mirrorlog
.RB { disk | core | mirrored }
.br
.BR \-m ,
.BR \-\-mirrors
.IR Number
.br
.BR \-n ,
.BR \-\-name
.IR Name
.br
.BR \-\-noudevsync
.br
.BR \-\-originname
.IR NewExternalOriginVolumeName
.br
.BR \-\-poolmetadata
.IR PoolMetadataLogicalVolume { Name | Path }
.br
.BR \-\-poolmetadatasize
.BR \fIPoolMetadataSize [ b | B | s | S | k | K | m | M | g | G ]
.br
.BR \-\-poolmetadataspare
.RB { y | n }
.br
.BR \-r ,
.BR \-\-readahead
.RB { \fIReadAheadSectors | auto | none }
.br
.BR \-R ,
.BR \-\-regionsize
.IR MirrorLogRegionSize
.br
.BR \-\-repair
.br
.BR \-\-replace
.IR PhysicalVolume
.br
.BR \-\-splitcache
.br
.BR \-\-splitmirrors
.IR Number
.br
.BR \-\-splitsnapshot
.br
.BR \-\-stripes
.IR Number
.br
.BR \-I ,
.BR \-\-stripesize
.IR StripeSize
.br
.B \-\-type striped
.br
.B \-\-type snapshot
|
.B \-\-snapshot
|
.B \-s
.br
.B \-\-type mirror
.br
.B \-\-type raid*
.br
.B \-\-type thin
|
.B \-\-thin
|
.B \-T
.br
.B \-\-type cache
|
.B \-\-cache
|
.B \-H
.br
.B \-\-type thin\-pool
.br
.B \-\-type cache\-pool
.br
.BR \-\-thinpool
.IR ThinPoolLogicalVolume { Name | Path }
.br
.BR \-\-trackchanges
.br
.BR \-\-uncache
.br
.BR \-Z ,
.BR \-\-zero
.RB { y | n }
.br

Common options:
.br
.BR \-A ,
.BR \-\-alloc
.IR AllocationPolicy
.br
.BR \-f ,
.BR \-\-force
.br
.BR \-\-commandprofile
.IR ProfileName
.br
.BR \-h ,
.BR \-? ,
.BR \-\-help
.br
.BR \-v ,
.BR \-\-verbose
.br
.BR \-y ,
.BR \-\-yes
.br
.BR \-\-version




.SH DESCRIPTION

lvconvert changes the LV type and includes various LV utilities.

To display the current LV type, run the command:

.B lvs \-o name,segtype
.IR VG / LV

To change the LV type, run the command:

.B lvconvert \-\-type
.I NewType
.IR VG / LV

.SS LV types

The LV type is also called the "segment type" or "segtype".

LVs with the following types can be modified by lvconvert:
.B striped,
.B snapshot,
.B mirror,
.B raid*,
.B thin,
.B cache,
.B thin\-pool,
.B cache\-pool.

The specific operations available on each LV type are listed below.

The
.B linear
type is equivalent to the
.B striped
type when one stripe exists.
In that case, the types can sometimes be used interchangably.

In most cases, the
.B mirror
type is deprecated and the
.B raid1
type should be used.  They are both implementations of mirroring.

The
.B raid*
type refers to one of many raid levels, e.g.
.B raid1,
.B raid5.

.SS LV layers

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 sometimes
called sub LVs.

Changing the LV type will often change the composition of sub LVs.

Sub LVs can be displayed with the command
.B lvs -a.

A command run on a visible LV sometimes operates on a sub LV rather than
the specified LV.  These cases are noted below.

Sometimes a sub LV must be specified directly on the command line, but
this is a non-standard form.  These cases may change in the future to
avoid the direct use of hidden LVs.

.SH COMMANDS

.SS Operations on a StripedLV with type striped or linear:

\&

.B lvconvert \-\-merge
VG/StripedLV
./" FIXME: use --merge-mirror
.br
\[bu]
Merge StripedLV into an LV when it is a previously split mirror.
.br
\[bu]
Options \-\-background, \-\-interval.
.br
\[bu]
See corresponding operation --splitmirrors.

.B lvconvert \-\-type snapshot
VG/StripedLV VG/SnapshotLV
.br
\[bu]
Recombine StripedLV with SnapshotLV which was previously split.
.br
\[bu]
Options \-\-chunksize, \-\-zero.
.br
\[bu]
See corresponding operation --splitsnapshot.

.B lvconvert \-\-type thin
VG/StripedLV
.br
\[bu]
Convert StripedLV to type thin with an external origin.
.br
\[bu]
StripedLV becomes a read\-only external origin LV with a new name.
.br
\[bu]
Requires \-\-thinpool to specify the thin pool to use.
.br
\[bu]
Options \-\-originname.

.B lvconvert \-\-type cache
VG/StripedLV
.br
\[bu]
Convert StripedLV to type cache.
.br
\[bu]
Requires \-\-cachepool to specify the cache pool to use.
.br
\[bu]
Options \-\-cachepolicy, \-\-cachesettings.

.B lvconvert \-\-type thin\-pool
VG/StripedLV
.br
\[bu]
Convert StripedLV to type thin\-pool.
.br
\[bu]
The StripedLV is used for thin pool data.
.br
\[bu]
Options \-\-chunksize, \-\-discards, \-\-poolmetadata{size,spare},
.br
  \-\-readahead, \-\-zero.

.B lvconvert \-\-type cache\-pool
VG/StripedLV
.br
\[bu]
Convert StripedLV to type cache\-pool.
.br
\[bu]
Options \-\-chunksize, \-\-poolmetadata{size,spare}.

.B lvconvert \-\-type mirror
VG/StripedLV
.br
\[bu]
Convert StripedLV to type mirror.
.br
\[bu]
Requires \-\-mirrors to specify the number of mirrors to use.
.br
\[bu]
Options \-\-mirrorlog, \-\-regionsize.

.B lvconvert \-\-type raid*
VG/StripedLV
.br
\[bu]
Convert StripedLV to type raid*.
.br
\[bu]
Required options depend on the raid level.

.SS Operations on RaidLV with type raid*:

\&

.B lvconvert \-\-mirrors
Number
VG/RaidLV
.br
\[bu]
Change the number of images in raid1 RaidLV.

.B lvconvert \-\-splitmirrors
Number
VG/RaidLV
.br
\[bu]
Split images from raid1 RaidLV and use them to create a new LV.
.br
\[bu]
Requires \-\-name for the new LV, or the use of \-\-trackchanges.

.B lvconvert \-\-merge
VG/RaidLV
./" FIXME: use --merge-mirror
.br
\[bu]
Merge RaidLV into an LV when it is a previously split mirror.
.br
\[bu]
Options \-\-background, \-\-interval.
.br
\[bu]
See corresponding operation --splitmirrors.

.B lvconvert \-\-repair
VG/RaidLV
.br
\[bu]
Options \-\-background, \-\-interval.
.br
\[bu]
Replace failed PVs in RaidLV.

.B lvconvert \-\-replace
PV
VG/RaidLV
.br
\[bu]
Replace specific PV(s) in a raid* LV with another PV.
.br
\[bu]
The new PV(s) to use can be optionally specified after the LV.
.br
\[bu]
Repeat to replace multiple: \-\-replace PV1 \-\-replace PV2 ...

.B lvconvert \-\-type snapshot
VG/RaidLV
VG/SnapshotLV
.br
\[bu]
Combine RaidLV with SnapshotLV that was previously split.
.br
\[bu]
Options \-\-chunksize, \-\-zero.
.br
\[bu]
See corresponding operation \-\-splitsnapshot.

.B lvconvert \-\-type thin
VG/RaidLV
.br
\[bu]
Convert RaidLV to type thin with an external origin.
.br
\[bu]
RaidLV becomes a read\-only external origin LV with a new name.
.br
\[bu]
Requires \-\-thinpool to specify the thin pool to use.
.br
\[bu]
Options \-\-originname.

.B lvconvert \-\-type cache
VG/RaidLV
.br
\[bu]
Convert RaidLV to type cache.
.br
\[bu]
Requires \-\-cachepool to specify the cache pool to use.
.br
\[bu]
Options \-\-cachepolicy, \-\-cachesettings.

.B lvconvert \-\-type thin\-pool
VG/RaidLV
.br
\[bu]
Convert RaidLV to type thin\-pool.
.br
\[bu]
The RaidLV is used for thin pool data.
.br
\[bu]
Options \-\-chunksize, \-\-discards, \-\-poolmetadata{size,spare},
.br
  \-\-readahead, \-\-zero.

.B lvconvert \-\-type cache\-pool
VG/RaidLV
.br
\[bu]
Convert RaidLV to type cache\-pool.
.br
\[bu]
Options \-\-chunksize, \-\-poolmetadata{size,spare}.

.B lvconvert \-\-type raid*
VG/RaidLV
.br
\[bu]
Convert RaidLV to use a different raid level.
.br
\[bu]
Required options depend on the raid level.

.B lvconvert \-\-type mirror
VG/RaidLV
.br
\[bu]
Convert RaidLV to type mirror.

.B lvconvert \-\-type striped
VG/RaidLV
.br
\[bu]
Convert RaidLV to type striped.

.B lvconvert \-\-type linear
VG/RaidLV
.br
\[bu]
Convert RaidLV to type linear.

.SS Operations on MirrorLV with type mirror:

\&

.B lvconvert \-\-mirrors
Number
VG/MirrorLV
.br
\[bu]
Change the number of images in MirrorLV.

.B lvconvert \-\-splitmirrors
Number
VG/MirrorLV
.br
\[bu]
Split images from MirrorLV and use them to create a new LV.
.br
\[bu]
Requires \-\-name for the new LV.

.B lvconvert \-\-mirrorlog
LogType
VG/MirrorLV
.br
\[bu]
Change the type of log used by MirrorLV.

.B lvconvert \-\-repair
VG/MirrorLV
.br
\[bu]
Options \-\-background, \-\-interval.
.br
\[bu]
Replace failed PVs in MirrorLV.

.B lvconvert \-\-type linear
VG/MirrorLV
.br
\[bu]
Convert MirrorLV to type linear.

.B lvconvert \-\-type raid*
VG/MirrorLV
.br
\[bu]
Convert MirrorLV to type raid*.
.br
\[bu]
Required options depend on the raid level.

.SS Operations on CachePoolLV with type cache\-pool:

\&

.B lvconvert \-\-splitcache
VG/CachePoolLV
.br
\[bu]
Split the cache LV from CachePoolLV.
.br
\[bu]
Equivalent to --splitcache on CacheLV.

.SS Operations on CacheLV with type cache:

\&

.B lvconvert \-\-splitcache
VG/CacheLV
.br
\[bu]
Split and keep the cache pool from CacheLV.

.B lvconvert \-\-uncache
VG/CacheLV
.br
\[bu]
Split and remove the cache pool from CacheLV.

.B lvconvert \-\-splitmirrors
Number
VG/CacheLV
.br
\[bu]
Split images from the mirrored origin of CacheLV to create a new LV.
.br
\[bu]
Operates on mirror or raid1 sub LV.
.br
\[bu]
Requires \-\-name for the new LV, or the use of \-\-trackchanges.

.B lvconvert \-\-type thin\-pool
VG/CacheLV
.br
\[bu]
Convert CacheLV to type thin-pool.
.br
\[bu]
The CacheLV is used for thin pool data.
.br
\[bu]
Options \-\-chunksize, \-\-discards, \-\-poolmetadata{size,spare},
.br
  \-\-readahead, \-\-zero.


.SS Operations on ThinPoolLV with type thin\-pool:

\&

.B lvconvert \-\-splitcache
VG/ThinPoolLV
.br
\[bu]
Split and keep the cache pool from the data portion of ThinPoolLV.
.br
\[bu]
Operates on the data sub LV of the thin pool LV.
.br
\[bu]
The data sub LV of the thin pool must be a cache LV.

.B lvconvert \-\-uncache
VG/ThinPoolLV
.br
\[bu]
Split and remove the cache pool from the data portion of ThinPoolLV.
.br
\[bu]
Operates on the data sub LV of the thin pool LV.
.br
\[bu]
The data sub LV of the thin pool must be a cache LV.

.B lvconvert \-\-type cache
VG/ThinPoolLV
.br
\[bu]
Convert the data portion of ThinPoolLV to type cache.
.br
\[bu]
Requires \-\-cachepool to specify the cache pool to use.
.br
\[bu]
Operates on the data sub LV of the thin pool LV.
.br
\[bu]
Options \-\-cachepolicy, \-\-cachesettings.

.B lvconvert \-\-repair
VG/ThinPoolLV
.br
\[bu]
Repair ThinPoolLV.

.SS Operations on ThinLV with type thin:

\&

.B lvconvert \-\-merge
VG/ThinLV
./" FIXME: use --merge-snapshot
.br
\[bu]
Merge ThinLV into its origin LV.
.br
\[bu]
ThinLV must have been created as a snapshot of another thin LV.
.br
\[bu]
Options \-\-background, \-\-interval.

.SS Operations on SnapshotLV with type snapshot:

\&

.B lvconvert \-\-splitsnapshot
VG/SnapshotLV
.br
\[bu]
Separate COW snapshot SnapshotLV from its origin LV.

.B lvconvert \-\-merge
VG/SnapshotLV
./" FIXME: use --merge-snapshot
.br
\[bu]
Merge COW snapshot SnapshotLV into its origin.
.br
\[bu]
Options \-\-background, \-\-interval.

.SH OPTIONS
.
See \fBlvm\fP(8) for common options.
.br
.
.HP
.BR \-b ,
.BR \-\-background
.br
If the operation requires polling, this option causes the command to
return before the operation is complete, and polling is done in the
background.
.
.HP
.BR \-\-cachepolicy
.IR Policy
.br
Specifies the cache policy for a cache LV.  Also see
.BR lvmcache (7).
.
.HP
.BR \-\-cachepool
.IR CachePoolLogicalVolume { Name | Path }
.br
Specifies the cache pool to use when converting an LV to a cache LV.  If
CachePoolLogicalVolume is not yet a cache pool, the command will attempt
to convert it into a cache pool prior to the cache LV conversion.
Also see
.BR lvmcache (7).
.
.HP
.BR \-\-cachesettings
.IB Key = Value
.br
Specifies tunable values for a cache LV.  (The default values should
usually be adequate.)  The special string value \fBdefault\fP switches
settings back to their default kernel values and removes them from the
list of settings stored in LVM metadata.
Also see
.BR lvmcache (7).
.
.HP
.BR \-c ,
.BR \-\-chunksize
.BR \fIChunkSize [ b | B | s | S | k | K | m | M | g | G ]
.br
Sets the chunk size for a snapshot, cache pool or thin pool.
The default unit is in kilobytes.
.sp
For snapshots, the value must be a power of 2 between 4KiB and 512KiB
and the default value is 4.
.sp
For a cache pool the value must be between 32KiB and 1GiB and
the default value is 64.
.sp
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.
(Early kernel support until thin target version 1.4 required the value
to be a power of 2.  Discards were not supported for non-power of 2 values
until thin target version 1.5.)
.
.HP
.BR \-\-corelog
.br
Specifies or changes the log type for a mirror LV.
It is an alias for \fB\-\-mirrorlog core\fP.
(This option does not apply to the \fBraid1\fP LV type.)
.
.HP
.BR \-\-discards
.RB { ignore | nopassdown | passdown }
.br
Specifies if discards will be processed by the thin layer in the
kernel and passed down to the Physical Volume.  This applies only
to thin pools.  The default is \fBpassdown\fP.
Also see
.BR lvmthin (7).
.
.HP
.BR \-H ,
.BR \-\-cache
.br
Alias for
.B \-\-type cache.
See COMMANDS description for
.br
.B lvconvert \-\-type cache.
.
.HP
.BR \-i ,
.BR \-\-interval
.IR Seconds
.br
Report progress as a percentage at regular intervals.
.
.HP
.BR \-\-merge
.br
Merges a snapshot that was split from an origin LV using
\fB\-\-splitsnapshot\fP, back into the origin LV.

Merges a raid1 image that was split from a raid1 LV using
\fB\-\-splitsnapshot\fP and \fB\-\-trackchanges\fP, back into
the original raid1 LV.

To check if the kernel supports the snapshot merge feature, look for
"snapshot\-merge" in the output of \fBdmsetup targets\fP.

When merging a snapshot, if both the origin and snapshot LVs are not open,
the merge will start immediately.  Otherwise, the merge will start the
first time either the origin or snapshot LV are activated and both are
closed.  Merging a snapshot into an origin that cannot be closed, for
example a root filesystem, is deferred until the next time the origin
volume is activated.  When merging starts, the resulting LV will have the
origin's name, minor number and UUID.  While the merge is in progress,
reads or writes to the origin appear as being directed to the snapshot
being merged.  When the merge finishes, the merged snapshot is removed.
Multiple snapshots may be specified on the command line or a @tag may be
used to specify multiple snapshots be merged to their respective origin.
.
.HP
.BR \-\-mirrorlog
.RB { disk | core | mirrored }
.br
Specifies or changes the log type for a mirror LV.
The default is \fBdisk\fP, which is persistent and requires
a small amount of storage space, usually on a separate device
from the data being mirrored.
\fBCore\fP may be useful for short-lived mirrors.  It means the mirror is
regenerated by copying the data from the first device again every
time the device is activated - e.g. possibly after every reboot.
Using \fBmirrored\fP will create a persistent log that is itself mirrored.
(This option does not apply to the \fBraid1\fP LV type.)
.
.HP
.BR \-m ,
.BR \-\-mirrors
.IR Number
.br
Specifies the number mirror images in addition to the original LV image,
e.g. \fB\-\-mirrors 1\fP means two copies of the data, the original and
one mirror image.

The current maximum is 9 providing 10 raid1 images.

This option is required when converting an LV to a \fBraid1\fP or
\fBmirror\fP LV.

This option can be used alone to change the number of mirror images in an
existing \fBraid1\fP or \fBmirror\fP LV.

The special case \fB\-\-mirrors 0\fP has been used historically to
indicate a linear LV with no mirror images.
.
.HP
.BR \-n ,
.BR \-\-name
.IR Name
.br
Specifies the name to use when the command is creating a new LV, e.g.
.B \-\-splitmirrors.
.
.HP
.BR \-\-noudevsync
.br
Disables udev synchronisation. The process will not wait for notification
from udev.  It will continue irrespective of any possible udev processing
in the background.  You should only use this if udev is not running or has
rules that ignore the devices LVM creates.
.
.HP
.BR \-\-originname
.IR NewExternalOriginVolumeName
.br
Specifies the name to use for the external origin LV when converting an LV
to a thin LV.  The LV being converted becomes a read\-only external origin
with this name.
.br
Without this option, the default name of "lvol<n>" will be generated where
<n> is the LVM internal number of the LV.
.br
.
.\" .HP
.\" .BR \-\-pooldatasize
.\" .IR PoolDataVolumeSize [ \fBbBsSkKmMgGtTpPeE ]
.\" .br
.\" Sets the size of pool's data logical volume.
.\" The option \fB\-\-size\fP could be still used with thin pools.
.
.HP
.BR \-\-poolmetadata
.IR PoolMetadataLogicalVolume { Name | Path }
.br
Specifies the LV to use for thin pool metadata when converting an LV to a
thin pool LV.
.br
Specifies the LV to use for cache pool metadata when converting an LV to a
cache pool LV.
.br
The size should be between 2MiB and 16GiB.
.br
(This option can also be used when a thin pool or cache pool are created
as an auxiliary operation within a different command.)
Also see
.BR lvmthin (7),
and
.BR lvmcache (7).
.
.HP
.BR \-\-poolmetadatasize
.BR \fIPoolMetadataSize [ b | B | s | S | k | K | m | M | g | G ]
.br
Specifies the size of a cache pool metadata LV or a thin pool metadata LV.
This is used if a command creates a pool metadata LV automatically as part
of the operation.  This option is not used when an existing LV is
specified as the pool metadata LV, i.e. \fB\-\-poolmetadata\fP.
The default unit is megabytes.
Also see
.BR lvmthin (7),
and
.BR lvmcache (7).
.
.HP
.BR \-\-poolmetadataspare
.RB { y | n }
.br
Specifies if a spare pool metadata LV should be created.
A spare pool metadata LV will be used for pool repair.
Only one spare pool metadata LV is maintained within a VG, with the size
of the largest existing pool metadata LV.
The default is \fBy\fPes.
.
.HP
.BR \-r ,
.BR \-\-readahead
.RB { \fIReadAheadSectors | auto | none }
.br
Specifies the read ahead sector count of a thin pool metadata LV.
The default value is \fBauto\fP which allows the kernel to choose
a suitable value automatically.
\fBNone\fP is equivalent to specifying zero.
.
.HP
.BR \-R ,
.BR \-\-regionsize
.IR MirrorLogRegionSize
.br
A mirror LV is divided into regions of this size (in MB), and the mirror
log uses this granularity to track which regions are in sync.
(This option does not apply to the \fBraid1\fP LV type.)
.
.HP
.BR \-\-repair
.br
Replaces failed PVs in a raid1 or mirror LV with other PVs available in
the VG.  By default, the original number of mirror images will be restored
if possible.  Specify \fB\-y\fP on the command line to skip the prompts.
Use \fB\-f\fP if you do not want any replacement.  You may use
\fB\-\-use\-policies\fP to use the device replacement policy specified in
\fBlvm.conf\fP(5), see \fBactivation/mirror_log_fault_policy\fP or
\fBactivation/mirror_device_fault_policy\fP.

When used with a thin pool LV, this option automates the use of the
\fBthin_repair\fP(8) tool on the thin pool.  This repairs a very limitted
number of problems.  Only inactive thin pools can be repaired.  There is
no validation of metadata between kernel and LVM.  This requires further
manual work.  After successfull repair the old unmodified metadata are
still available in "<pool>_meta<n>" LV.
Also see
.BR lvmthin (7).
.
.HP
.BR \-\-replace
.IR PhysicalVolume
.br
Remove the specified device \fIPhysicalVolume\fP and replace it with one
that is available in the VG, or from a specific list of PVs specified on
the command line following the LV name. This option may be repeated multiple
times depending on the RaidLV type.
.
.HP
.BR \-s ,
.BR \-\-snapshot
.br
Alias for
.B \-\-type snapshot.
See COMMANDS description for
.br
.B lvconvert \-\-type snapshot.
.HP
.BR \-\-split
.br
Separates \fISplitableLogicalVolume\fP.
This option tries to detect the necessary split operation from its arguments.
Avoid using this option and use one of the following instead:
.B \-\-splitcache, \-\-splitmirrors, \-\-splitsnapshot.
.
.HP
.BR \-\-splitcache
.br
Separates a cache pool from a cache LV, and keeps the unused cache pool
LV.  Before the separation, the cache is flushed.  See similar option
.B \-\-uncache.
Also see
.BR lvmcache (7).
.
.HP
.BR \-\-splitmirrors
.IR Number
.br
Splits the specified number of images from a \fBraid1\fP or \fBmirror\fP
LV and uses them to create a new LV.

If \fB\-\-trackchanges\fP is also specified, changes to the raid1 LV are
tracked while the split LV remains detached.
.B lvconvert \-\-merge
can be used to recombine the split images with the original raid1 LV.

A name can be specified for the new LV with \fB\-\-name\fP (a name is
required without \fB\-\-trackchanges\fP).
.
.HP
.BR \-\-splitsnapshot
.br
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.
See corresponding operation
.B lvconvert \-\-type snapshot.
.
.HP
.BR \-\-stripes
.IR Number
.br
Specifies the number of stripes in a striped LV.  This is the number of
physical volumes (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 \fB\-\-stripesize\fP).  This does not apply to
existing allocated space, only newly allocated space can be striped.
.
.HP
.BR \-I ,
.BR \-\-stripesize
.IR StripeSize
.br
Specifies the stripe size in kilobytes for a striped LV.  The stripe size
is the number of kilobytes written to each stripe, i.e. to one device,
before writing to the next stripe/device.  StripeSize must be a power of 2
and cannot exceed the VG physical extent (PE) size.
.
.HP
.BR \-\-type
.IR SegmentType
.br
Converts an LV from one segment type to another.
See COMMANDS section for a description of converting between each type.
.
.HP
.BR \-\-thinpool
.IR ThinPoolLogicalVolume { Name | Path }
.br
Specifies the thin pool to use when converting an LV to a thin LV.  If
ThinPoolLogicalVolume is not yet a thin pool, the command will attempt to
convert it to a thin pool prior to the thin LV conversion.
Also see
.BR lvmthin (7).
.
.HP
.BR \-\-trackchanges
.br
Can be used with \fB\-\-splitmirrors\fP on a raid1 LV.  This causes
changes to the original raid1 LV to be tracked while the split images
remain detached.  This allows the read\-only detached image(s) to be
merged efficiently back into the raid1 LV later.  Only the regions with
changed data are resynchronized during merge.  (This option only applies
to the \fBraid1\fP LV type.)
.
.HP
.BR \-T ,
.BR \-\-thin
.br
Alias for
.B \-\-type thin.
See COMMANDS description for
.br
.B lvconvert \-\-type thin.
.
.HP
.BR \-\-uncache
.br
Separates a cache pool from a cache LV, and removes the unused cache pool
LV.  Before the separation, the cache is flushed.  See similar option
.B \-\-splitcache.
Also see
.BR lvmcache (7).
.
.HP
.BR \-Z ,
.BR \-\-zero
.RB { y | n }
.br
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.
Also see
.BR lvmthin (7).
.

.SH Examples
.
Convert a linear LV to a two-way mirror LV:
.br
.B lvconvert \-\-type mirror \-\-mirrors 1 vg/lvol1

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

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

Convert a mirror LV to use a disk log:
.br
.B lvconvert \-\-mirrorlog disk vg/lvol1

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

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

./" Split and merge a COW snapshot:
./" TODO
Convert a linear LV to a two-way mirror LV, allocating new extents from specific
PV ranges:
.br
.B 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:
.br
.B lvconvert \-\-type linear vg/lvol1 /dev/sda

Split one image from a mirror or raid1 LV, making it a new LV:
.br
.B 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:
.br
.B lvconvert \-\-splitmirrors 1 \-\-trackchanges vg/lvol1

Merge an image (that was previously created with \-\-splitmirrors and
\-\-trackchanges) back into the original raid1 LV:
.br
.B lvconvert \-\-merge vg/lvol1_rimage_1
./" FIXME: use merge-mirror

Replace PV /dev/sdb1 with PV /dev/sdf1 in a raid1/4/5/6/10 LV:
.br
.B 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:
.br
.B lvconvert \-\-replace /dev/sdb1 \-\-replace /dev/sdc1 \-\-replace /dev/sdd1
.RS
.B vg/lvol1 /dev/sd[fgh]1
.RE

Replace the maximum of 2 PVs /dev/sd[bc]1 with PVs /dev/sd[gh]1 in a raid6 LV:
.br
.B lvconvert \-\-replace /dev/sdb1 \-\-replace /dev/sdc1 vg/lvol1 /dev/sd[gh]1

Convert an LV into a thin LV in the specified thin pool.  The existing LV
is used as an external read\-only origin for the new thin LV.
.br
.B lvconvert \-\-type thin \-\-thinpool vg/tpool1 vg/lvol1

Convert an LV into a thin LV in the specified thin pool.  The existing LV
is used as an external read\-only origin for the new thin LV, and is
renamed "external":
.br
.B lvconvert \-\-type thin \-\-thinpool vg/tpool1
.RS
.B \-\-originname external vg/lvol1
.RE

Convert an LV to a cache pool LV using another specified LV for cache pool
metadata:
.br
.B lvconvert \-\-type cache-pool \-\-poolmetadata vg/poolmeta1 vg/lvol1

Convert an LV to a cache LV using the specified cache pool and chunk size:
.br
.B lvconvert \-\-type cache \-\-cachepool vg/cpool1 \-c 128 vg/lvol1

Detach and keep the cache pool from a cache LV:
.br
.B lvconvert \-\-splitcache vg/lvol1

Detach and remove the cache pool from a cache LV:
.br
.B lvconvert \-\-uncache vg/lvol1

.SH SEE ALSO
.BR lvm (8),
.BR lvm.conf (5),
.BR lvmcache (7),
.BR lvmthin (7),
.BR lvdisplay (8),
.BR lvextend (8),
.BR lvreduce (8),
.BR lvremove (8),
.BR lvrename (8),
.BR lvscan (8),
.BR vgcreate (8),
.BR cache_dump (8),
.BR cache_repair (8),
.BR cache_restore (8),
.BR thin_dump (8),
.BR thin_repair (8),
.BR thin_restore (8)
