LVMTHIN(7)LVMTHIN(7)NAMElvmthin - LVM thin provisioning
DESCRIPTION
Blocks in a standard logical volume are allocated when the LV is cre‐
ated, but blocks in a thin provisioned logical volume are allocated as
they are written. Because of this, a thin provisioned LV is given a
virtual size, and can then be much larger than physically available
storage. The amount of physical storage provided for thin provisioned
LVs can be increased later as the need arises.
Blocks in a standard LV are allocated (during creation) from the VG,
but blocks in a thin LV are allocated (during use) from a special "thin
pool LV". The thin pool LV contains blocks of physical storage, and
blocks in thin LVs just reference blocks in the thin pool LV.
A thin pool LV must be created before thin LVs can be created within
it. A thin pool LV is created by combining two standard LVs: a large
data LV that will hold blocks for thin LVs, and a metadata LV that will
hold metadata. The metadata tracks which data blocks belong to each
thin LV.
Snapshots of thin LVs are efficient because the data blocks common to a
thin LV and its snapshot are shared. Snapshots may be taken of thin
LVs or of other thin snapshots. Blocks common to recursive snapshots
are also shared in the thin pool. There is no limit to or degradation
from sequences of snapshots.
As thin LVs or snapshot LVs are written to, they consume data blocks in
the thin pool. As free data blocks in the pool decrease, more free
blocks may need to be supplied. This is done by extending the thin
pool data LV with additional physical space from the VG. Removing thin
LVs or snapshots from the thin pool can also free blocks in the thin
pool. However, removing LVs is not always an effective way of freeing
space in a thin pool because the amount is limited to the number of
blocks not shared with other LVs in the pool.
Incremental block allocation from thin pools can cause thin LVs to
become fragmented. Standard LVs generally avoid this problem by allo‐
cating all the blocks at once during creation.
Thin Terms
ThinDataLV
thin data LV
large LV created in a VG
used by thin pool to store ThinLV blocks
ThinMetaLV
thin metadata LV
small LV created in a VG
used by thin pool to track data block usage
ThinPoolLV
thin pool LV
combination of ThinDataLV and ThinMetaLV
contains ThinLVs and SnapLVs
ThinLV
thin LV
created from ThinPoolLV
appears blank after creation
SnapLV
snapshot LV
created from ThinPoolLV
appears as a snapshot of another LV after creation
Thin Usage
The primary method for using lvm thin provisioning:
1. create ThinDataLV
Create an LV that will hold thin pool data.
Command
lvcreate -n ThinDataLV -L LargeSize VG
Example
# lvcreate -n pool0 -L 100G vg
2. create ThinMetaLV
Create an LV that will hold thin pool metadata.
Command
lvcreate -n ThinMetaLV -L SmallSize VG
Example
# lvcreate -n pool0meta -L 1G vg
# lvs
pool0 vg -wi-a----- 10.00g
pool0meta vg -wi-a----- 1.00g
3. create ThinPoolLV
Combine the data and metadata LVs into a thin pool LV.
ThinDataLV is renamed to hidden ThinPoolLV_tdata.
ThinMetaLV is renamed to hidden ThinPoolLV_tmeta.
The new ThinPoolLV takes the previous name of ThinDataLV.
Command
lvconvert --thinpool VG/ThinDataLV --poolmetadata VG/ThinMetaLV
Example
# lvconvert --thinpool vg/pool0 --poolmetadata vg/pool0meta
# lvs vg/pool0
LV VG Attr LSize Pool Origin Data%
pool0 vg twi-a-tz-- 10.00g 0.00
# lvs -a
pool0 vg twi-a-tz-- 10.00g
[pool0_tdata] vg Twi-ao---- 10.00g
[pool0_tmeta] vg ewi-ao---- 1.00g
4. create ThinLV
Create a new thin LV from the thin pool LV.
The thin LV is created with a virtual size.
Multiple new thin LVs may be created in the thin pool.
Thin LV names must be unique in the VG.
The thinpool argument specifies which thin pool will
contain the ThinLV.
Command
lvcreate --type thin -n ThinLV -V VirtualSize --thinpool VG/ThinPoolLV
Example
Create a thin LV in a thin pool:
# lvcreate --type thin -n thin1 -V 1T --thinpool vg/pool0
Create another thin LV in the same thin pool:
# lvcreate --type thin -n thin2 -V 1T --thinpool vg/pool0
# lvs vg/thin1 vg/thin2
LV VG Attr LSize Pool Origin Data%
thin1 vg Vwi-a-tz-- 1.00t pool0 0.00
thin2 vg Vwi-a-tz-- 1.00t pool0 0.00
5. create SnapLV
Create snapshots of an existing ThinLV or SnapLV.
Command
lvcreate --type thin -n SnapLV -s ThinLV --thinpool VG/ThinPoolLV
lvcreate --type thin -n SnapLV -s PrevSnapLV --thinpool VG/ThinPoolLV
Example
Create first snapshot of an existing ThinLV:
# lvcreate --type thin -n thin1s1 -s thin1 --thinpool vg/pool0
Create second snapshot of the same ThinLV:
# lvcreate --type thin -n thin1s2 -s thin1 --thinpool vg/pool0
Create a snapshot of the first snapshot:
# lvcreate --type thin -n thin1s1s1 -s thin1s1 --thinpool vg/pool0
# lvs vg/thin1s1 vg/thin1s2 vg/thin1s1s1
LV VG Attr LSize Pool Origin
thin1s1 vg Vwi---tz-k 1.00t pool0 thin1
thin1s2 vg Vwi---tz-k 1.00t pool0 thin1
thin1s1s1 vg Vwi---tz-k 1.00t pool0 thin1s1
6. activate SnapLV
Thin snapshots are created with the persistent "activation skip"
flag, indicated by the "k" attribute. Use -K with lvchange
or vgchange to activate thin snapshots with the "k" attribute.
Command
lvchange -ay -K VG/SnapLV
Example
# lvchange -ay -K vg/thin1s1
# lvs vg/thin1s1
thin1s1 vg Vwi-a-tz-k 1.00t pool0 thin1
Thin Topics
Specify devices for data and metadata LVs
Tolerate device failures using raid
Spare metadata LV
Metadata check and repair
Automatic pool metadata LV
Activation of thin snapshots
Removing thin pool LVs, thin LVs and snapshots
Manually manage free data space of thin pool LV
Manually manage free metadata space of a thin pool LV
Using fstrim to increase free space in a thin pool LV
Automatically extend thin pool LV
Data space exhaustion
Metadata space exhaustion
Zeroing
Discard
Chunk size
Size of pool metadata LV
Create a thin snapshot of an external, read only LV
Convert a standard LV to a thin LV with an external origin
Single step thin pool LV creation
Single step thin pool LV and thin LV creation
Specify devices for data and metadata LVs
The data and metadata LVs in a thin pool are best created on separate
physical devices. To do that, specify the device name(s) at the end of
the lvcreate line. It can be especially helpful to use fast devices
for the metadata LV.
lvcreate -n ThinDataLV -L LargeSize VG LargePV
lvcreate -n ThinMetaLV -L SmallSize VG SmallPV
lvconvert --thinpool VG/ThinDataLV --poolmetadata VG/ThinMetaLV
Example
# lvcreate -n pool0 -L 100G vg /dev/sdA
# lvcreate -n pool0meta -L 1G vg /dev/sdB
# lvconvert --thinpool vg/pool0 --poolmetadata vg/pool0meta
lvm.conf(5) thin_pool_metadata_require_separate_pvs
controls the default PV usage for thin pool creation.
Tolerate device failures using raid
To tolerate device failures, use raid for the pool data LV and pool
metadata LV. This is especially recommended for pool metadata LVs.
lvcreate --type raid1 -m 1 -n ThinMetaLV -L SmallSize VG PVA PVB
lvcreate --type raid1 -m 1 -n ThinDataLV -L LargeSize VG PVC PVD
lvconvert --thinpool VG/ThinDataLV --poolmetadata VG/ThinMetaLV
Example
# lvcreate --type raid1 -m 1 -n pool0 -L 100G vg /dev/sdA /dev/sdB
# lvcreate --type raid1 -m 1 -n pool0meta -L 1G vg /dev/sdC /dev/sdD
# lvconvert --thinpool vg/pool0 --poolmetadata vg/pool0meta
Spare metadata LV
The first time a thin pool LV is created, lvm will create a spare meta‐
data LV in the VG. This behavior can be controlled with the option
--poolmetadataspare y|n. (Future thin pool creations will also attempt
to create the pmspare LV if none exists.)
To create the pmspare ("pool metadata spare") LV, lvm first creates an
LV with a default name, e.g. lvol0, and then converts this LV to a hid‐
den LV with the _pmspare suffix, e.g. lvol0_pmspare.
One pmspare LV is kept in a VG to be used for any thin pool.
The pmspare LV cannot be created explicitly, but may be removed explic‐
itly.
Example
# lvcreate -n pool0 -L 10G vg
# lvcreate -n pool0meta -L 10G vg
# lvconvert --thinpool vg/pool0 --poolmetadata vg/pool0meta
# lvs -a
[lvol0_pmspare] vg ewi------- 10.00g
pool0 vg twi---tz-- 10.00g
[pool0_tdata] vg Twi------- 10.00g
[pool0_tmeta] vg ewi------- 1.00g
The "Metadata check and repair" section describes the use of the pms‐
pare LV.
Metadata check and repair
If thin pool metadata is damaged, it may be repairable. Checking and
repairing thin pool metadata is analagous to running fsck on a file
system.
When a thin pool LV is activated, lvm runs the thin_check command to
check the correctness of the metadata on the pool metadata LV.
lvm.conf(5) thin_check_executable
can be set to an empty string ("") to disable the thin_check step.
This is not recommended.
lvm.conf(5) thin_check_options
controls the command options used for the thin_check command.
If the thin_check command finds a problem with the metadata, the thin
pool LV is not activated, and the thin pool metadata should be
repaired.
Command to repair a thin pool:
lvconvert --repair VG/ThinPoolLV
Repair performs the following steps:
1. Creates a new, repaired copy of the metadata.
lvconvert runs the thin_repair command to read damaged metadata from
the existing pool metadata LV, and writes a new repaired copy to the
VG's pmspare LV.
2. Replaces the thin pool metadata LV.
If step 1 is successful, the thin pool metadata LV is replaced with the
pmspare LV containing the corrected metadata. The previous thin pool
metadata LV, containing the damaged metadata, becomes visible with the
new name ThinPoolLV_tmetaN (where N is 0,1,...).
If the repair works, the thin pool LV and its thin LVs can be acti‐
vated, and the LV containing the damaged thin pool metadata can be
removed. It may be useful to move the new metadata LV (previously pms‐
pare) to a better PV.
If the repair does not work, the thin pool LV and its thin LVs are
lost.
If metadata is manually restored with thin_repair directly, the pool
metadata LV can be manually swapped with another LV containing new
metadata:
lvconvert --thinpool VG/ThinPoolLV --poolmetadata VG/NewThinMetaLV
Automatic pool metadata LV
A thin data LV can be converted to a thin pool LV without specifying a
thin pool metadata LV. LVM will automatically create a metadata LV
from the same VG.
lvcreate -n ThinDataLV -L LargeSize VG
lvconvert --thinpool VG/ThinDataLV
Example
# lvcreate -n pool0 -L 10G vg
# lvconvert --thinpool vg/pool0
# lvs -a
pool0 vg twi-a-tz-- 10.00g
[pool0_tdata] vg Twi-ao---- 10.00g
[pool0_tmeta] vg ewi-ao---- 16.00m
Activation of thin snapshots
When a thin snapshot LV is created, it is by default given the "activa‐
tion skip" flag. This flag is indicated by the "k" attribute displayed
by lvs:
# lvs vg/thin1s1
LV VG Attr LSize Pool Origin
thin1s1 vg Vwi---tz-k 1.00t pool0 thin1
This flag causes the snapshot LV to be skipped, i.e. not activated, by
normal activation commands. The skipping behavior does not apply to
deactivation commands.
A snapshot LV with the "k" attribute can be activated using the -K (or
--ignoreactivationskip) option in addition to the standard -ay (or
--activate y) option.
Command to activate a thin snapshot LV:
lvchange -ay -K VG/SnapLV
The persistent "activation skip" flag can be turned off during lvcre‐
ate, or later with lvchange using the -kn (or --setactivationskip n)
option. It can be turned on again with -ky (or --setactivationskip y).
When the "activation skip" flag is removed, normal activation commands
will activate the LV, and the -K activation option is not needed.
Command to create snapshot LV without the activation skip flag:
lvcreate --type thin -n SnapLV -kn -s ThinLV --thinpool VG/ThinPoolLV
Command to remove the activation skip flag from a snapshot LV:
lvchange -kn VG/SnapLV
lvm.conf(5) auto_set_activation_skip
controls the default activation skip setting used by lvcreate.
Removing thin pool LVs, thin LVs and snapshots
Removing a thin LV and its related snapshots returns the blocks it used
to the thin pool LV. These blocks will be reused for other thin LVs
and snapshots.
Removing a thin pool LV removes both the data LV and metadata LV and
returns the space to the VG.
lvremove of thin pool LVs, thin LVs and snapshots cannot be reversed
with vgcfgrestore.
vgcfgbackup does not back up thin pool metadata.
Manually manage free data space of thin pool LV
The available free space in a thin pool LV can be displayed with the
lvs command. Free space can be added by extending the thin pool LV.
Command to extend thin pool data space:
lvextend -L Size VG/ThinPoolLV
Example
1. A thin pool LV is using 26.96% of its data blocks.
# lvs
LV VG Attr LSize Pool Origin Data%
pool0 vg twi-a-tz-- 10.00g 26.96
2. Double the amount of physical space in the thin pool LV.
# lvextend -L+10G vg/pool0
3. The percentage of used data blocks is half the previous value.
# lvs
LV VG Attr LSize Pool Origin Data%
pool0 vg twi-a-tz-- 20.00g 13.48
Other methods of increasing free data space in a thin pool LV include
removing a thin LV and its related snapsots, or running fstrim on the
file system using a thin LV.
Manually manage free metadata space of a thin pool LV
The available metadata space in a thin pool LV can be displayed with
the lvs -o+metadata_percent command.
Command to extend thin pool metadata space:
lvextend -L Size VG/ThinPoolLV_tmeta
Example
1. A thin pool LV is using 12.40% of its metadata blocks.
# lvs -oname,size,data_percent,metadata_percent vg/pool0
LV LSize Data% Meta%
pool0 20.00g 13.48 12.40
2. Display a thin pool LV with its component thin data LV and thin
metadata LV.
# lvs -a -oname,attr,size vg
LV Attr LSize
pool0 twi-a-tz-- 20.00g
[pool0_tdata] Twi-ao---- 20.00g
[pool0_tmeta] ewi-ao---- 12.00m
3. Double the amount of physical space in the thin metadata LV.
# lvextend -L+12M vg/pool0_tmeta
4. The percentage of used metadata blocks is half the previous value.
# lvs -a -oname,size,data_percent,metadata_percent vg
LV LSize Data% Meta%
pool0 20.00g 13.48 6.20
[pool0_tdata] 20.00g
[pool0_tmeta] 24.00m
Using fstrim to increase free space in a thin pool LV
Removing files in a file system on top of a thin LV does not generally
add free space back to the thin pool. Manually running the fstrim com‐
mand can return space back to the thin pool that had been used by
removed files. fstrim uses discards and will not work if the thin pool
LV has discards mode set to ignore.
Example
A thin pool has 10G of physical data space, and a thin LV has a virtual
size of 100G. Writing a 1G file to the file system reduces the free
space in the thin pool by 10% and increases the virtual usage of the
file system by 1%. Removing the 1G file restores the virtual 1% to the
file system, but does not restore the physical 10% to the thin pool.
The fstrim command restores the physical space to the thin pool.
# lvs -a -oname,attr,size,pool_lv,origin,data_percent,metadata_percent vg
LV Attr LSize Pool Origin Data% Meta%
pool0 twi-a-tz-- 10.00g 47.01 21.03
thin1 Vwi-aotz-- 100.00g pool0 2.70
# df -h /mnt/X
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg-thin1 99G 1.1G 93G 2% /mnt/X
# dd if=/dev/zero of=/mnt/X/1Gfile bs=4096 count=262144; sync
# lvs
pool0 vg twi-a-tz-- 10.00g 57.01 25.26
thin1 vg Vwi-aotz-- 100.00g pool0 3.70
# df -h /mnt/X
/dev/mapper/vg-thin1 99G 2.1G 92G 3% /mnt/X
# rm /mnt/X/1Gfile
# lvs
pool0 vg twi-a-tz-- 10.00g 57.01 25.26
thin1 vg Vwi-aotz-- 100.00g pool0 3.70
# df -h /mnt/X
/dev/mapper/vg-thin1 99G 1.1G 93G 2% /mnt/X
# fstrim -v /mnt/X
# lvs
pool0 vg twi-a-tz-- 10.00g 47.01 21.03
thin1 vg Vwi-aotz-- 100.00g pool0 2.70
Automatically extend thin pool LV
An lvm daemon (dmeventd) will by default monitor the data usage of thin
pool LVs and extend them when the usage reaches a certain level. The
necessary free space must exist in the VG to extend the thin pool LVs.
Command to enable or disable the monitoring and automatic extension of
an existing thin pool LV:
lvchange --monitor {y|n} VG/ThinPoolLV
lvm.conf(5) thin_pool_autoextend_threshold thin_pool_autoextend_percent
control the default autoextend behavior.
thin_pool_autoextend_threshold is a percentage value that defines when
the thin pool LV should be extended. Setting this to 100 disables
automatic extention. The minimum value is 50.
thin_pool_autoextend_percent defines how much extra data space should
be added to the thin pool, in percent of its current size.
Warnings are emitted through syslog when the use of a pool reaches 80%,
85%, 90% and 95%.
Example
If thin_pool_autoextend_threshold is 70 and thin_pool_autoextend_per‐
cent is 20, whenever a pool exceeds 70% usage, it will be extended by
another 20%. For a 1G pool, using 700M will trigger a resize to 1.2G.
When the usage exceeds 840M, the pool will be extended to 1.44G, and so
on.
Data space exhaustion
If thin pool data space is exhausted, writes to thin LVs will be queued
until the the data space is extended. Reading is still possible.
When data space is exhausted, the lvs command displays 100 under Data%
for the thin pool LV:
# lvs vg/pool0
LV VG Attr LSize Pool Origin Data%
pool0 vg twi-a-tz-- 512.00m 100.00
A thin pool can run out of data blocks for any of the following rea‐
sons:
1. Automatic extension of the thin pool is disabled, and the thin pool
is not manually extended. (Disabling automatic extension is not recom‐
mended.)
2. The dmeventd daemon is not running and the thin pool is not manually
extended. (Disabling dmeventd is not recommended.)
3. Automatic extension of the thin pool is too slow given the rate of
writes to thin LVs in the pool. (This can be addressed by tuning the
thin_pool_autoextend_threshold and thin_pool_autoextend_percent.)
4. The VG does have enough free blocks to extend the thin pool.
The response to data space exhaustion is to extend the thin pool. This
is described in the section "Manually manage free data space of thin
pool LV".
Metadata space exhaustion
If thin pool metadata space is exhausted (or a thin pool metadata oper‐
ation fails), errors will be returned for IO operations on thin LVs.
When metadata space is exhausted, the lvs command displays 100 under
Meta% for the thin pool LV:
# lvs -o lv_name,size,data_percent,metadata_percent vg/pool0
LV LSize Data% Meta%
pool0 100.00
The same reasons for thin pool data space exhaustion apply to thin pool
metadata space.
Metadata space exhaustion can lead to inconsistent thin pool metadata
and inconsistent file systems, so the response requires offline check‐
ing and repair.
1. Deactivate the thin pool LV, or reboot the system if this is not
possible.
2. Repair thin pool with lvconvert --repair.
See "Metadata check and repair".
3. Extend pool metadata space with lvextend VG/ThinPoolLV_tmeta.
See "Manually manage free metadata space of a thin pool LV".
4. Check and repair file system with fsck.
Zeroing
When a thin pool provisions a new data block for a thin LV, the new
block is first overwritten with zeros. The zeroing mode is indicated
by the "z" attribute displayed by lvs. The option -Z (or --zero) can
be added to commands to specify the zeroing mode.
Command to set the zeroing mode when creating a thin pool LV:
lvconvert -Z{y|n} --thinpool VG/ThinDataLV --poolmetadata VG/ThinMetaLV
Command to change the zeroing mode of an existing thin pool LV:
lvchange -Z{y|n} VG/ThinPoolLV
If zeroing mode is changed from "n" to "y", previously provisioned
blocks are not zeroed.
Provisioning of large zeroed chunks impacts performance.
lvm.conf(5) thin_pool_zero
controls the default zeroing mode used when creating a thin pool.
Discard
The discard behavior of a thin pool LV determines how discard requests
are handled. Possible discard behaviors:
ignore: Ignore any discards that are received.
nopassdown: Process any discards in the thin pool itself and allow the
no longer needed extends to be overwritten by new data.
passdown: Process discards in the thin pool (as with nopassdown), and
pass the discards down the the underlying device. This is the default
mode.
Command to display the current discard mode of a thin pool LV:
lvs -o+discards VG/ThinPoolLV
Command to set the discard mode when creating a thin pool LV:
lvconvert --discards {ignore|nopassdown|passdown}
--thinpool VG/ThinDataLV --poolmetadata VG/ThinMetaLV
Command to change the discard mode of an existing thin pool LV:
lvchange --discards {ignore|nopassdown|passdown} VG/ThinPoolLV
Example
# lvs -o name,discards vg/pool0
pool0 passdown
# lvchange --discards ignore vg/pool0
lvm.conf(5) thin_pool_discards
controls the default discards mode used when creating a thin pool.
Chunk size
The size of data blocks managed by a thin pool can be specified with
the --chunksize option when the thin pool LV is created. The default
unit is kilobytes and the default value is 64KiB. The value must be a
power of two between 4KiB and 1GiB.
When a thin pool is used primarily for the thin provisioning feature, a
larger value is optimal. To optimize for a lot of snapshotting, a
smaller value reduces copying time and consumes less space.
Command to display the thin pool LV chunk size:
lvs -o+chunksize VG/ThinPoolLV
Example
# lvs -o name,chunksize
pool0 64.00k
lvm.conf(5) thin_pool_chunk_size
controls the default chunk size used when creating a thin pool.
Size of pool metadata LV
The amount of thin metadata depends on how many blocks are shared
between thin LVs (i.e. through snapshots). A thin pool with many snap‐
shots may need a larger metadata LV.
The range of supported metadata LV sizes is 2MiB to 16GiB.
The default size is estimated with the formula:
ThinPoolLVSize / ThinPoolLVChunkSize * 64b.
When creating a thin metadata LV explicitly, the size is specified in
the lvcreate command. When a command automatically creates a thin
metadata LV, the --poolmetadatasize option can be used specify a non-
default size. The default unit is megabytes.
Create a thin snapshot of an external, read only LV
Thin snapshots are typically taken of other thin LVs or other thin
snapshot LVs within the same thin pool. It is also possible to take
thin snapshots of external, read only LVs. Writes to the snapshot are
stored in the thin pool, and the external LV is used to read unwritten
parts of the thin snapshot.
lvcreate --type thin -n SnapLV -s VG/ExternalOriginLV
--thinpool VG/ThinPoolLV
Example
# lvchange -an vg/lve
# lvchange --permission r vg/lve
# lvcreate --type thin -n snaplve -s vg/lve --thinpool vg/pool0
# lvs vg/lve vg/snaplve
LV VG Attr LSize Pool Origin Data%
lve vg ori------- 10.00g
snaplve vg Vwi-a-tz-- 10.00g pool0 lve 0.00
Convert a standard LV to a thin LV with an external origin
A new thin LV can be created and given the name of an existing standard
LV. At the same time, the existing LV is converted to a read only
external LV with a new name. Unwritten portions of the thin LV are
read from the external LV. The new name given to the existing LV can
be specified with --originname, otherwise the existing LV will be given
a default name, e.g. lvol#.
Convert ExampleLV into a read only external LV with the new name NewEx‐
ternalOriginLV, and create a new thin LV that is given the previous
name of ExampleLV.
lvconvert --type thin --thinpool VG/ThinPoolLV
--originname NewExternalOriginLV --thin VG/ExampleLV
Example
# lvcreate -n lv_example -L 10G vg
# lvs
lv_example vg -wi-a----- 10.00g
# lvconvert --type thin --thinpool vg/pool0
--originname lv_external --thin vg/lv_example
# lvs
LV VG Attr LSize Pool Origin
lv_example vg Vwi-a-tz-- 10.00g pool0 lv_external
lv_external vg ori------- 10.00g
Single step thin pool LV creation
A thin pool LV can be created with a single lvcreate command, rather
than using lvconvert on existing LVs. This one command creates a thin
data LV, a thin metadata LV, and combines the two into a thin pool LV.
lvcreate -L LargeSize --thinpool VG/ThinPoolLV
Example
# lvcreate -l1 --thinpool vg/pool0
# lvs vg/pool0
LV VG Attr LSize Pool Origin Data%
pool0 vg twi-a-tz-- 8.00m 0.00
# lvs -a
pool0 vg twi-a-tz-- 8.00m
[pool0_tdata] vg Twi-ao---- 8.00m
[pool0_tmeta] vg ewi-ao---- 8.00m
Single step thin pool LV and thin LV creation
A thin pool LV and a thin LV can be created with a single lvcreate com‐
mand. This one command creates a thin data LV, a thin metadata LV,
combines the two into a thin pool LV, and creates a thin LV in the new
pool.
-L LargeSize specifies the physical size of the thin pool LV.
-V VirtualSize specifies the virtual size of the thin LV.
lvcreate -L LargeSize -V VirtualSize -n ThinLV --thinpool VG/ThinPoolLV
Equivalent to:
lvcreate -L LargeSize --thinpool VG/ThinPoolLV
lvcreate --type thin -n ThinLV -V VirtualSize --thinpool VG/ThinPoolLV
Example
# lvcreate -L8M -V2G -n thin1 --thinpool vg/pool0
# lvs -a
pool0 vg twi-a-tz-- 8.00m
[pool0_tdata] vg Twi-ao---- 8.00m
[pool0_tmeta] vg ewi-ao---- 8.00m
thin1 vg Vwi-a-tz-- 2.00g pool0
SEE ALSOlvm(8), lvm.conf(5), lvcreate(8), lvconvert(8), lvchange(8), lvex‐
tend(8), lvremove(8), lvs(8), thin_dump(8), thin_repair(8)thin_restore(8)Red Hat, Inc LVM TOOLS 2.02.106(2) (2014-04-10) LVMTHIN(7)
