LVCONVERT(8) System Manager's Manual LVCONVERT(8)
NAME
lvconvert -- Change logical volume layout
SYNOPSIS
lvconvert option_args position_args
[ option_args ]
[ position_args ]
--alloc contiguous|cling|cling_by_tags|normal|anywhere|inherit
-b|--background
-H|--cache
--cachedevice PV
--cachemetadataformat auto|1|2
--cachemode writethrough|writeback|passthrough
--cachepolicy String
--cachepool LV
--cachesettings String
--cachesize Size[m|UNIT]
--cachevol LV
-c|--chunksize Size[k|UNIT]
--commandprofile String
--compression y|n
--config String
-d|--debug
--deduplication y|n
--devices PV
--devicesfile String
--discards passdown|nopassdown|ignore
--driverloaded y|n
--errorwhenfull y|n
-f|--force
-h|--help
-i|--interval Number
--journal String
--lockopt String
--longhelp
--merge
--mergemirrors
--mergesnapshot
--mergethin
--metadataprofile String
--mirrorlog core|disk
-m|--mirrors [+|-]Number
-n|--name String
--nohints
--nolocking
--noudevsync
--originname LV
--poolmetadata LV
--poolmetadatasize Size[m|UNIT]
--poolmetadataspare y|n
--profile String
-q|--quiet
--raidintegrity y|n
--raidintegrityblocksize Number
--raidintegritymode String
-r|--readahead auto|none|Number
-R|--regionsize Size[m|UNIT]
--repair
--replace PV
-s|--snapshot
--splitcache
--splitmirrors Number
--splitsnapshot
--startpoll
--stripes Number
-I|--stripesize Size[k|UNIT]
--swapmetadata
-t|--test
-T|--thin
--thinpool LV
--trackchanges
--type linear|striped|snapshot|raid|mirror|thin|thin-pool|vdo|
vdo-pool|cache|cache-pool|writecache
--uncache
--usepolicies
--vdopool LV
--vdosettings String
-v|--verbose
--version
-V|--virtualsize Size[m|UNIT]
-y|--yes
-Z|--zero y|n
DESCRIPTION
lvconvert changes the LV type and includes utilities for LV data main-
tenance. 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 physi-
cal devices. In other cases, hidden LVs (dm devices) are layered be-
tween 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 ex-
ists. In that case, the types can sometimes be used interchangeably.
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 par-
ity blocks. The parity blocks can be used for data block recovery in
case devices fail. A maximum number of one device in a raid5 LV may
fail, and two in case of raid6. Striped raid types typically rotate the
parity and data blocks for performance reasons, thus avoiding con-
tention 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-asymmet-
ric (raid5_ra), right-symmetric (raid5_rs) and raid5_n, which doesn't
rotate parity blocks. Layouts of raid6 are: zero-restart (raid6_zr with
alias raid6), next-restart (raid6_nr), and next-continue (raid6_nc).
Layouts including _n allow for conversion between raid levels (raid5_n
to raid6 or raid5_n to striped/raid0/raid0_meta). Additionally, special
raid6 layouts for raid level conversions between raid5 and raid6 are:
raid6_ls_6, raid6_rs_6, raid6_la_6 and raid6_ra_6. Those correspond to
their raid5 counterparts (e.g. raid5_rs can be directly converted to
raid6_rs_6 and vice-versa).
raid10 (an alias for raid10_near) is currently limited to one data copy
and even number of sub LVs. This is a mirror group layout, thus a sin-
gle sub LV may fail per mirror group without data loss.
Striped raid types support converting the layout, their stripesize and
their number of stripes.
The striped raid types combined with raid1 allow for conversion from
linear -> striped/raid0/raid0_meta and vice-versa by e.g. linear <->
raid1 <-> raid5_n (then adding stripes) <-> striped/raid0/raid0_meta.
USAGE
Convert LV to linear.
lvconvert --type linear LV
[ COMMON_OPTIONS ]
[ PV ... ]
--
Convert LV to striped.
lvconvert --type striped LV
[ -I|--stripesize Size[k|UNIT] ]
[ -R|--regionsize Size[m|UNIT] ]
[ -i|--interval Number ]
[ --stripes Number ]
[ COMMON_OPTIONS ]
[ PV ... ]
--
Convert LV to type mirror (also see type raid1),
lvconvert --type mirror LV
[ -m|--mirrors [+|-]Number ]
[ -I|--stripesize Size[k|UNIT] ]
[ -R|--regionsize Size[m|UNIT] ]
[ -i|--interval Number ]
[ --stripes Number ]
[ --mirrorlog core|disk ]
[ COMMON_OPTIONS ]
[ PV ... ]
--
Convert LV to raid or change raid layout
(a specific raid level must be used, e.g. raid1).
lvconvert --type raid LV
[ -m|--mirrors [+|-]Number ]
[ -I|--stripesize Size[k|UNIT] ]
[ -R|--regionsize Size[m|UNIT] ]
[ -i|--interval Number ]
[ --stripes Number ]
[ COMMON_OPTIONS ]
[ PV ... ]
--
Convert LV to raid1 or mirror, or change number of mirror images.
lvconvert -m|--mirrors [+|-]Number LV
[ -R|--regionsize Size[m|UNIT] ]
[ -i|--interval Number ]
[ --mirrorlog core|disk ]
[ COMMON_OPTIONS ]
[ PV ... ]
--
Convert raid LV to change number of stripe images.
lvconvert --stripes Number LV1
[ -i|--interval Number ]
[ -R|--regionsize Size[m|UNIT] ]
[ -I|--stripesize Size[k|UNIT] ]
[ COMMON_OPTIONS ]
[ PV ... ]
LV1 types: raid
--
Convert raid LV to change the stripe size.
lvconvert -I|--stripesize Size[k|UNIT] LV1
[ -i|--interval Number ]
[ -R|--regionsize Size[m|UNIT] ]
[ COMMON_OPTIONS ]
LV1 types: raid
--
Split images from a raid1 or mirror LV and use them to create a new LV.
lvconvert --splitmirrors Number -n|--name LV_new LV1
[ COMMON_OPTIONS ]
[ PV ... ]
LV1 types: cache mirror raid1
--
Split images from a raid1 LV and track changes to origin for later
merge.
lvconvert --splitmirrors Number --trackchanges LV1
[ COMMON_OPTIONS ]
[ PV ... ]
LV1 types: cache raid1
--
Merge LV images that were split from a raid1 LV.
lvconvert --mergemirrors VG|LV1|Tag ...
[ COMMON_OPTIONS ]
LV1 types: linear raid
--
Convert LV to a thin LV, using the original LV as an external origin.
lvconvert --type thin --thinpool LV LV1
[ -T|--thin ]
[ -r|--readahead auto|none|Number ]
[ -c|--chunksize Size[k|UNIT] ]
[ -Z|--zero y|n ]
[ --originname LV_new ]
[ --poolmetadata LV ]
[ --poolmetadatasize Size[m|UNIT] ]
[ --poolmetadataspare y|n ]
[ --metadataprofile String ]
[ COMMON_OPTIONS ]
LV1 types: linear striped thin cache raid error zero
--
Attach a cache pool to an LV, converts the LV to type cache.
lvconvert --type cache --cachepool LV LV1
[ -H|--cache ]
[ -Z|--zero y|n ]
[ -r|--readahead auto|none|Number ]
[ -c|--chunksize Size[k|UNIT] ]
[ --cachemetadataformat auto|1|2 ]
[ --cachemode writethrough|writeback|passthrough ]
[ --cachepolicy String ]
[ --cachesettings String ]
[ --poolmetadata LV ]
[ --poolmetadatasize Size[m|UNIT] ]
[ --poolmetadataspare y|n ]
[ --metadataprofile String ]
[ COMMON_OPTIONS ]
LV1 types: linear striped thinpool vdo vdopool vdopooldata raid
--
Attach a writecache to an LV, converts the LV to type writecache.
lvconvert --type writecache --cachevol LV LV1
[ --cachesettings String ]
[ COMMON_OPTIONS ]
LV1 types: linear striped thinpool raid
--
Attach a cache to an LV, converts the LV to type cache.
lvconvert --type cache --cachevol LV LV1
[ -H|--cache ]
[ -Z|--zero y|n ]
[ -c|--chunksize Size[k|UNIT] ]
[ --cachemetadataformat auto|1|2 ]
[ --cachemode writethrough|writeback|passthrough ]
[ --cachepolicy String ]
[ --cachesettings String ]
[ --poolmetadatasize Size[m|UNIT] ]
[ COMMON_OPTIONS ]
LV1 types: linear striped thinpool raid
--
Add a writecache to an LV, using a specified cache device.
lvconvert --type writecache --cachedevice PV LV1
[ --cachesize Size[m|UNIT] ]
[ --cachesettings String ]
[ COMMON_OPTIONS ]
LV1 types: linear striped thinpool raid
--
Add a cache to an LV, using a specified cache device.
lvconvert --type cache --cachedevice PV LV1
[ -c|--chunksize Size[k|UNIT] ]
[ --cachesize Size[m|UNIT] ]
[ --cachesettings String ]
[ COMMON_OPTIONS ]
LV1 types: linear striped thinpool raid
--
Convert LV to type thin-pool.
lvconvert --type thin-pool LV1
[ -I|--stripesize Size[k|UNIT] ]
[ -r|--readahead auto|none|Number ]
[ -c|--chunksize Size[k|UNIT] ]
[ -Z|--zero y|n ]
[ --stripes Number ]
[ --discards passdown|nopassdown|ignore ]
[ --errorwhenfull y|n ]
[ --poolmetadata LV ]
[ --poolmetadatasize Size[m|UNIT] ]
[ --poolmetadataspare y|n ]
[ --metadataprofile String ]
[ COMMON_OPTIONS ]
[ PV ... ]
LV1 types: linear striped cache raid error zero writecache
--
Convert LV to type cache-pool.
lvconvert --type cache-pool LV1
[ -Z|--zero y|n ]
[ -r|--readahead auto|none|Number ]
[ -c|--chunksize Size[k|UNIT] ]
[ --cachemetadataformat auto|1|2 ]
[ --cachemode writethrough|writeback|passthrough ]
[ --cachepolicy String ]
[ --cachesettings String ]
[ --poolmetadata LV ]
[ --poolmetadatasize Size[m|UNIT] ]
[ --poolmetadataspare y|n ]
[ --metadataprofile String ]
[ COMMON_OPTIONS ]
[ PV ... ]
LV1 types: linear striped raid
--
Convert LV to type vdopool.
lvconvert --type vdo-pool LV1
[ -n|--name LV_new ]
[ -V|--virtualsize Size[m|UNIT] ]
[ -r|--readahead auto|none|Number ]
[ -Z|--zero y|n ]
[ --metadataprofile String ]
[ --compression y|n ]
[ --deduplication y|n ]
[ --vdosettings String ]
[ COMMON_OPTIONS ]
LV1 types: linear striped cache raid
--
Detach a cache from an LV.
lvconvert --splitcache LV1
[ --cachesettings String ]
[ COMMON_OPTIONS ]
LV1 types: thinpool cache cachepool vdopool writecache
--
Merge thin LV into its origin LV.
lvconvert --mergethin LV1 ...
[ COMMON_OPTIONS ]
LV1 types: thin
--
Merge COW snapshot LV into its origin.
lvconvert --mergesnapshot LV1 ...
[ -i|--interval Number ]
[ COMMON_OPTIONS ]
LV1 types: snapshot
--
Combine a former COW snapshot (second arg) with a former
origin LV (first arg) to reverse a splitsnapshot command.
lvconvert --type snapshot LV LV1
[ -s|--snapshot ]
[ -c|--chunksize Size[k|UNIT] ]
[ -Z|--zero y|n ]
[ COMMON_OPTIONS ]
LV1 types: linear striped
--
Replace failed PVs in a raid or mirror LV.
Repair a thin pool.
Repair a cache pool.
lvconvert --repair LV1
[ -i|--interval Number ]
[ --usepolicies ]
[ --poolmetadataspare y|n ]
[ COMMON_OPTIONS ]
[ PV ... ]
LV1 types: thinpool cache cachepool mirror raid
--
Replace specific PV(s) in a raid LV with another PV.
lvconvert --replace PV LV1
[ COMMON_OPTIONS ]
[ PV ... ]
LV1 types: raid
--
Poll LV to continue conversion.
lvconvert --startpoll LV1
[ COMMON_OPTIONS ]
LV1 types: mirror raid
--
Add or remove data integrity checksums to raid images.
lvconvert --raidintegrity y|n LV1
[ --raidintegritymode String ]
[ --raidintegrityblocksize Number ]
[ COMMON_OPTIONS ]
[ PV ... ]
LV1 types: raid
--
Common options for command:
[ -b|--background ]
[ -f|--force ]
[ --alloc contiguous|cling|cling_by_tags|normal|anywhere|inherit
]
[ --noudevsync ]
Common options for lvm:
[ -d|--debug ]
[ -h|--help ]
[ -q|--quiet ]
[ -t|--test ]
[ -v|--verbose ]
[ -y|--yes ]
[ --commandprofile String ]
[ --config String ]
[ --devices PV ]
[ --devicesfile String ]
[ --driverloaded y|n ]
[ --journal String ]
[ --lockopt String ]
[ --longhelp ]
[ --nohints ]
[ --nolocking ]
[ --profile String ]
[ --version ]
OPTIONS
--alloc contiguous|cling|cling_by_tags|normal|anywhere|inherit
Determines the allocation policy when a command needs to allo-
cate Physical Extents (PEs) from the VG. Each VG and LV has an
allocation policy which can be changed with vgchange/lvchange,
or overridden on the command line. normal applies common sense
rules such as not placing parallel stripes on the same PV. in-
herit applies the VG policy to an LV. contiguous requires new
PEs be placed adjacent to existing PEs. cling places new PEs on
the same PV as existing PEs in the same stripe of the LV. If
there are sufficient PEs for an allocation, but normal does not
use them, anywhere will use them even if it reduces performance,
e.g. by placing two stripes on the same PV. Optional positional
PV args on the command line can also be used to limit which PVs
the command will use for allocation. See lvm(8) for more infor-
mation about allocation.
-b|--background
If the operation requires polling, this option causes the com-
mand 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 com-
plete. writeback considers a write complete as soon as it is
stored in the cache pool. writethough considers a write com-
plete 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 associ-
ated 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 informa-
tion.
--cachepolicy String
Specifies the cache policy for a cache LV. See lvmcache(7) for
more information.
--cachepool LV
The name of a cache pool.
--cachesettings String
Specifies tunable values for a cache LV in "Key = Value" form.
Repeat this option to specify multiple values. (The default
values should usually be adequate.) The special string value
default switches settings back to their default kernel values
and removes them from the list of settings stored in LVM metada-
ta. 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 de-
fault value starts with 64 and scales up to fit the pool metada-
ta size within 128MiB, if the pool metadata size is not speci-
fied. 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 vol-
ume. See lvmvdo(7) for more information about VDO usage.
--config String
Config settings for the command. These override lvm.conf(5) set-
tings. The String arg uses the same format as lvm.conf(5), or
may use section/field syntax. See lvm.conf(5) for more informa-
tion about config.
-d|--debug ...
Set debug level. Repeat from 1 to 6 times to increase the detail
of messages sent to the log file and/or syslog (if configured).
--deduplication y|n
Controls whether deduplication is enabled or disable for VDO
volume. See lvmvdo(7) for more information about VDO usage.
--devices PV
Restricts the devices that are visible and accessible to the
command. Devices not listed will appear to be missing. This op-
tion can be repeated, or accepts a comma separated list of de-
vices. 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) com-
mand. This overrides the lvm.conf(5) devices/devicesfile and
devices/use_devicesfile settings.
--discards passdown|nopassdown|ignore
Specifies how the device-mapper thin pool layer in the kernel
should handle discards. ignore causes the thin pool to ignore
discards. nopassdown causes the thin pool to process discards
itself to allow reuse of unneeded extents in the thin pool.
passdown causes the thin pool to process discards itself (like
nopassdown) and pass the discards to the underlying device. See
lvmthin(7) for more information.
--driverloaded y|n
If set to no, the command will not attempt to use device-mapper.
For testing and debugging.
--errorwhenfull y|n
Specifies thin pool behavior when data space is exhausted. When
yes, device-mapper will immediately return an error when a thin
pool is full and an I/O request requires space. When no, de-
vice-mapper will queue these I/O requests for a period of time
to allow the thin pool to be extended. Errors are returned if
no space is available after the timeout. (Also see dm-thin-pool
kernel module option no_space_timeout.) See lvmthin(7) for more
information.
-f|--force ...
Override various checks, confirmations and protections. Use
with extreme caution.
-h|--help
Display help text.
-i|--interval Number
Report progress at regular intervals.
--journal String
Record information in the systemd journal. This information is
in addition to information enabled by the lvm.conf log/journal
setting. command: record information about the command. out-
put: record the default command output. debug: record full com-
mand debugging.
--lockopt String
Used to pass options for special cases to lvmlockd. See lvm-
lockd(8) for more information.
--longhelp
Display long help text.
--merge
An alias for --mergethin, --mergemirrors, or --mergesnapshot,
depending on the type of LV.
--mergemirrors
Merge LV images that were split from a raid1 LV. See --split-
mirrors with --trackchanges.
--mergesnapshot
Merge COW snapshot LV into its origin. When merging a snapshot,
if both the origin and snapshot LVs are not open, the merge will
start immediately. Otherwise, the merge will start the first
time either the origin or snapshot LV are activated and both are
closed. Merging a snapshot into an origin that cannot be closed,
for example a root filesystem, is deferred until the next time
the origin volume is activated. When merging starts, the 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 command line or a @tag may be used to
specify multiple snapshots be merged to their respective origin.
--mergethin
Merge thin LV into its origin LV. The origin thin LV takes the
content of the thin snapshot, and the thin snapshot LV is re-
moved. See lvmthin(7) for more information.
--metadataprofile String
The metadata profile to use for command configuration. See
lvm.conf(5) for more information about profiles.
--mirrorlog core|disk
Specifies the type of mirror log for LVs with the "mirror" type
(does not apply to the "raid1" type.) disk is a persistent log
and requires a small amount of storage space, usually on a sepa-
rate device from the data being mirrored. core is not persis-
tent; 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 origi-
nal LV image, e.g. --mirrors 1 means there are two images of the
data, the original and one mirror image. Optional positional PV
args on the command line can specify the devices the images
should be placed on. There are two mirroring implementations:
"raid1" and "mirror". These are the names of the corresponding
LV types, or "segment types". Use the --type option to specify
which to use (raid1 is default, and mirror is legacy) Use
lvm.conf(5) global/mirror_segtype_default and global/raid10_seg-
type_default to configure the default types. The plus prefix +
can be used, in which case the number is added to the current
number of images, or the minus prefix - can be used, in which
case the number is subtracted from the current number of images.
See lvmraid(7) for more information.
-n|--name String
Specifies the name of a new LV. When unspecified, a default
name of "lvol#" is generated, where # is a number generated by
LVM.
--nohints
Do not use the hints file to locate devices for PVs. A command
may read more devices to find PVs when hints are not used. The
command will still perform standard hint file invalidation where
appropriate.
--nolocking
Disable locking.
--noudevsync
Disables udev synchronisation. The process will not wait for no-
tification from udev. It will continue irrespective of any pos-
sible 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 con-
verting an LV to a thin LV. The LV being converted becomes a
read-only external origin with this name.
--poolmetadata LV
The name of a an LV to use for storing pool metadata.
--poolmetadatasize Size[m|UNIT]
Specifies the size of the new pool metadata LV.
--poolmetadataspare y|n
Enable or disable the automatic creation and management of a
spare pool metadata LV in the VG. A spare metadata LV is re-
served space that can be used when repairing a pool.
--profile String
An alias for --commandprofile or --metadataprofile, depending on
the command.
-q|--quiet ...
Suppress output and log messages. Overrides --debug and --ver-
bose. 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 in-
tegrity 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 check-
sums consistent in case of a crash. The bitmap areas are recal-
culated after a crash, so corruption in those areas would not be
detected. A journal does not have this problem. The journal
mode doubles writes to storage, but can improve performance for
scattered writes packed into a single journal write. bitmap
mode can in theory achieve full write throughput of the device,
but would not benefit from the potential scattered write opti-
mization.
-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 automatical-
ly. 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 util-
ity on a thin pool. See lvmraid(7) and lvmthin(7) for more in-
formation.
--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 re-
verse a previous --splitsnapshot command.
--splitcache
Separates a cache pool from a cache LV, and keeps the unused
cache pool LV. Before the separation, the cache is flushed. Al-
so see --uncache.
--splitmirrors Number
Splits the specified number of images from a raid1 or mirror LV
and uses them to create a new LV. If --trackchanges is also
specified, changes to the raid1 LV are tracked while the split
LV remains detached. If --name is specified, then the images
are permanently split from the original LV and changes are not
tracked.
--splitsnapshot
Separates a COW snapshot from its origin LV. The LV that is
split off contains the chunks that differ from the origin LV
along with metadata describing them. This LV can be wiped and
then destroyed with lvremove.
--startpoll
Start polling an LV to continue processing a conversion.
--stripes Number
Specifies the number of stripes in a striped LV. This is the
number of PVs (devices) that a striped LV is spread across. Data
that appears sequential in the LV is spread across multiple de-
vices 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 anoth-
er 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 di-
rectly and used with thin provisioning tools: cache_dump(8),
cache_repair(8), cache_restore(8), thin_dump(8), thin_repair(8),
thin_restore(8).
-t|--test
Run in test mode. Commands will not update metadata. This is
implemented by disabling all metadata writing but nevertheless
returning success to the calling function. This may lead to un-
usual error messages in multi-stage operations if a tool relies
on reading back metadata it believes has changed but hasn't.
-T|--thin
Specifies the command is handling a thin LV or thin pool. See
--type thin, --type thin-pool, and --virtualsize. See
lvmthin(7) for more information about LVM thin provisioning.
--thinpool LV
The name of a thin pool LV.
--trackchanges
Can be used with --splitmirrors on a raid1 LV. This causes
changes to the original raid1 LV to be tracked while the split
images remain detached. This is a temporary state that allows
the read-only detached image to be merged efficiently back into
the raid1 LV later. Only the regions with changed data are
resynchronized during merge. While a raid1 LV is tracking
changes, operations on it are limited to merging the split image
(see --mergemirrors) or permanently splitting the image (see
--splitmirrors with --name.
--type linear|striped|snapshot|raid|mirror|thin|thin-pool|vdo|vdo-pool|
cache|cache-pool|writecache
The LV type, also known as "segment type" or "segtype". See us-
age descriptions for the specific ways to use these types. For
more information about redundancy and performance (raid<N>, mir-
ror, 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 snap-
shots (snapshot) see usage definitions. For VDO (vdo) see lvmv-
do(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. Al-
so see --splitcache.
--usepolicies
Perform an operation according to the policy configured in
lvm.conf(5) or a profile.
--vdopool LV
The name of a VDO pool LV. See lvmvdo(7) for more information
about VDO usage.
--vdosettings String
Specifies tunable VDO options for VDO LVs. Use the form 'op-
tion=value' or 'option1=value option2=value', or repeat
--vdosettings for each option being set. These settings over-
ride the default VDO behaviors. To remove vdosettings and re-
vert to the default VDO behaviors, use --vdosettings 'default'.
See lvmvdo(7) for more information.
-v|--verbose ...
Set verbose level. Repeat from 1 to 4 times to increase the de-
tail 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 in-
formation about LVM thin provisioning. Using virtual size (-V)
and actual size (-L) together creates a sparse LV. lvm.conf(5)
global/sparse_segtype_default determines the default segment
type used to create a sparse LV. Anything written to a sparse
LV will be returned when reading from it. Reading from other
areas of the LV will return blocks of zeros. When using a snap-
shot to create a sparse LV, a hidden virtual device is created
using the zero target, and the LV has the suffix _vorigin.
Snapshots are less efficient than thin provisioning when creat-
ing large sparse LVs (GiB).
-y|--yes
Do not prompt for confirmation interactively but always assume
the answer yes. Use with extreme caution. (For automatic no,
see -qq.)
-Z|--zero y|n
For snapshots, this controls zeroing of the first 4KiB of data
in the snapshot. If the LV is read-only, the snapshot will not
be zeroed. For thin pools, this controls zeroing of provisioned
blocks. Provisioning of large zeroed chunks negatively impacts
performance.
VARIABLES
VG Volume Group name. See lvm(8) for valid names.
LV Logical Volume name. See lvm(8) for valid names. An LV posi-
tional arg generally includes the VG name and LV name, e.g.
VG/LV. LV1 indicates the LV must have a specific type, where
the accepted LV types are listed. (raid represents raid<N>
type).
PV Physical Volume name, a device path under /dev. For commands
managing physical extents, a PV positional arg generally accepts
a suffix indicating a range (or multiple ranges) of physical ex-
tents (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 con-
tent.
Size[UNIT]
Size is an input number that accepts an optional unit. Input
units are always treated as base two values, regardless of capi-
talization, e.g. 'k' and 'K' both refer to 1024. The default
input unit is specified by letter, followed by |UNIT. UNIT rep-
resents other possible input units: b|B is bytes, s|S is sectors
of 512 bytes, k|K is KiB, m|M is MiB, g|G is GiB, t|T is TiB,
p|P is PiB, e|E is EiB. (This should not be confused with the
output control --units, where capital letters mean multiple of
1000.)
ENVIRONMENT VARIABLES
See lvm(8) for information about environment variables used by lvm.
For example, LVM_VG_NAME can generally be substituted for a required VG
parameter.
ADVANCED USAGE
Alternate command forms, advanced command usage, and listing of all
valid syntax for completeness.
Change the region size of an LV.
lvconvert -R|--regionsize Size[m|UNIT] LV1
[ COMMON_OPTIONS ]
LV1 types: raid
--
Change the type of mirror log used by a mirror LV.
lvconvert --mirrorlog core|disk LV1
[ COMMON_OPTIONS ]
[ PV ... ]
LV1 types: mirror
--
Convert LV to a thin LV, using the original LV as an external origin.
lvconvert -T|--thin --thinpool LV LV1
[ --type thin ] (implied)
[ -r|--readahead auto|none|Number ]
[ -c|--chunksize Size[k|UNIT] ]
[ -Z|--zero y|n ]
[ --originname LV_new ]
[ --poolmetadata LV ]
[ --poolmetadatasize Size[m|UNIT] ]
[ --poolmetadataspare y|n ]
[ --metadataprofile String ]
[ COMMON_OPTIONS ]
LV1 types: linear striped thin cache raid error zero
--
Attach a cache pool to an LV.
lvconvert -H|--cache --cachepool LV LV1
[ --type cache ] (implied)
[ -Z|--zero y|n ]
[ -r|--readahead auto|none|Number ]
[ -c|--chunksize Size[k|UNIT] ]
[ --cachemetadataformat auto|1|2 ]
[ --cachemode writethrough|writeback|passthrough ]
[ --cachepolicy String ]
[ --cachesettings String ]
[ --poolmetadata LV ]
[ --poolmetadatasize Size[m|UNIT] ]
[ --poolmetadataspare y|n ]
[ --metadataprofile String ]
[ COMMON_OPTIONS ]
LV1 types: linear striped thinpool vdo vdopool vdopooldata raid
--
Attach a cache to an LV, converts the LV to type cache.
lvconvert -H|--cache --cachevol LV LV1
[ -Z|--zero y|n ]
[ -c|--chunksize Size[k|UNIT] ]
[ --cachemetadataformat auto|1|2 ]
[ --cachemode writethrough|writeback|passthrough ]
[ --cachepolicy String ]
[ --cachesettings String ]
[ --poolmetadatasize Size[m|UNIT] ]
[ COMMON_OPTIONS ]
LV1 types: linear striped thinpool raid
--
Convert LV to type vdopool.
lvconvert --vdopool LV
[ --type vdo-pool ] (implied)
[ -r|--readahead auto|none|Number ]
[ -Z|--zero y|n ]
[ -n|--name LV_new ]
[ -V|--virtualsize Size[m|UNIT] ]
[ --metadataprofile String ]
[ --compression y|n ]
[ --deduplication y|n ]
[ --vdosettings String ]
[ COMMON_OPTIONS ]
--
Detach and delete a cache from an LV.
lvconvert --uncache LV1
[ --cachesettings String ]
[ COMMON_OPTIONS ]
LV1 types: thinpool cache vdopool writecache
--
Swap metadata LV in a thin pool or cache pool (for repair only).
lvconvert --swapmetadata --poolmetadata LV LV1
[ -c|--chunksize Size[k|UNIT] ]
[ COMMON_OPTIONS ]
LV1 types: thinpool cachepool
--
Merge LV that was split from a mirror (variant, use --mergemirrors).
Merge thin LV into its origin LV (variant, use --mergethin).
Merge COW snapshot LV into its origin (variant, use --mergesnapshot).
lvconvert --merge VG|LV1|Tag ...
[ -i|--interval Number ]
[ COMMON_OPTIONS ]
LV1 types: linear striped snapshot thin raid
--
Separate a COW snapshot from its origin LV.
lvconvert --splitsnapshot LV1
[ COMMON_OPTIONS ]
LV1 types: snapshot
--
Combine a former COW snapshot (second arg) with a former
origin LV (first arg) to reverse a splitsnapshot command.
lvconvert -s|--snapshot LV LV1
[ --type snapshot ] (implied)
[ -c|--chunksize Size[k|UNIT] ]
[ -Z|--zero y|n ]
[ COMMON_OPTIONS ]
LV1 types: linear striped
--
Poll LV to continue conversion (also see --startpoll)
or waits till conversion/mirror syncing is finished
lvconvert LV1
[ COMMON_OPTIONS ]
LV1 types: mirror raid
--
NOTES
This previous command syntax would perform two different operations:
lvconvert --thinpool LV1 --poolmetadata LV2
If LV1 was not a thin pool, the command would convert LV1 to a thin
pool, optionally using a specified LV for metadata. But, if LV1 was
already a thin pool, the command would swap the current metadata LV
with LV2 (for repair purposes.)
In the same way, this previous command syntax would perform two differ-
ent operations:
lvconvert --cachepool LV1 --poolmetadata LV2
If LV1 was not a cache pool, the command would convert LV1 to a cache
pool, optionally using a specified LV for metadata. But, if LV1 was
already a cache pool, the command would swap the current metadata LV
with LV2 (for repair purposes.)
EXAMPLES
Convert a linear LV to a two-way mirror LV.
lvconvert --type mirror --mirrors 1 vg/lvol1
Convert a linear LV to a two-way RAID1 LV.
lvconvert --type raid1 --mirrors 1 vg/lvol1
Convert a mirror LV to use an in-memory log.
lvconvert --mirrorlog core vg/lvol1
Convert a mirror LV to use a disk log.
lvconvert --mirrorlog disk vg/lvol1
Convert a mirror or raid1 LV to a linear LV.
lvconvert --type linear vg/lvol1
Convert a mirror LV to a raid1 LV with the same number of images.
lvconvert --type raid1 vg/lvol1
Convert a linear LV to a two-way mirror LV, allocating new extents from
specific PV ranges.
lvconvert --mirrors 1 vg/lvol1 /dev/sda:0-15 /dev/sdb:0-15
Convert a mirror LV to a linear LV, freeing physical extents from a
specific PV.
lvconvert --type linear vg/lvol1 /dev/sda
Split one image from a mirror or raid1 LV, making it a new LV.
lvconvert --splitmirrors 1 --name lv_split vg/lvol1
Split one image from a raid1 LV, and track changes made to the raid1 LV
while the split image remains detached.
lvconvert --splitmirrors 1 --trackchanges vg/lvol1
Merge an image (that was previously created with --splitmirrors and
--trackchanges) back into the original raid1 LV.
lvconvert --mergemirrors vg/lvol1_rimage_1
Replace PV /dev/sdb1 with PV /dev/sdf1 in a raid1/4/5/6/10 LV.
lvconvert --replace /dev/sdb1 vg/lvol1 /dev/sdf1
Replace 3 PVs /dev/sd[b-d]1 with PVs /dev/sd[f-h]1 in a raid1 LV.
lvconvert --replace /dev/sdb1 --replace /dev/sdc1 --replace /dev/sdd1
vg/lvol1 /dev/sd[fgh]1
Replace the maximum of 2 PVs /dev/sd[bc]1 with PVs /dev/sd[gh]1 in a
raid6 LV.
lvconvert --replace /dev/sdb1 --replace /dev/sdc1 vg/lvol1 /dev/sd[gh]1
Convert an LV into a thin LV in the specified thin pool. The existing
LV is used as an external read-only origin for the new thin LV.
lvconvert --type thin --thinpool vg/tpool1 vg/lvol1
Convert an LV into a thin LV in the specified thin pool. The existing
LV is used as an external read-only origin for the new thin LV, and is
renamed "external".
lvconvert --type thin --thinpool vg/tpool1
--originname external vg/lvol1
Convert an LV to a cache pool LV using another specified LV for cache
pool metadata.
lvconvert --type cache-pool --poolmetadata vg/poolmeta1 vg/lvol1
Convert an LV to a cache LV using the specified cache pool and chunk
size.
lvconvert --type cache --cachepool vg/cpool1 -c 128 vg/lvol1
Detach and keep the cache pool from a cache LV.
lvconvert --splitcache vg/lvol1
Detach and remove the cache pool from a cache LV.
lvconvert --uncache vg/lvol1
SEE ALSO
lvm(8), lvm.conf(5), lvmconfig(8), lvmdevices(8),
pvchange(8), pvck(8), pvcreate(8), pvdisplay(8), pvmove(8),
pvremove(8), pvresize(8), pvs(8), pvscan(8),
vgcfgbackup(8), vgcfgrestore(8), vgchange(8), vgck(8), vgcreate(8),
vgconvert(8), vgdisplay(8), vgexport(8), vgextend(8), vgimport(8),
vgimportclone(8), vgimportdevices(8), vgmerge(8), vgmknodes(8),
vgreduce(8), vgremove(8), vgrename(8), vgs(8), vgscan(8), vgsplit(8),
lvcreate(8), lvchange(8), lvconvert(8), lvdisplay(8), lvextend(8),
lvreduce(8), lvremove(8), lvrename(8), lvresize(8), lvs(8), lvscan(8),
lvm-fullreport(8), lvm-lvpoll(8), lvm2-activation-generator(8),
blkdeactivate(8), lvmdump(8),
dmeventd(8), lvmpolld(8), lvmlockd(8), lvmlockctl(8), cmirrord(8),
lvmdbusd(8), fsadm(8),
lvmsystemid(7), lvmreport(7), lvmraid(7), lvmthin(7), lvmcache(7)
Red Hat, Inc. LVM TOOLS 2.03.14(2)-RHEL8 (2021-10-20) LVCONVERT(8)
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