Provided by: lvm2_2.02.98-6ubuntu2_amd64 
NAME
lvcreate - create a logical volume in an existing volume group
SYNOPSIS
lvcreate [--addtag Tag] [--alloc AllocationPolicy] [-a|--activate [a|e|l]{y|n}]
[-A|--autobackup {y|n}] [-C|--contiguous {y|n}] [-d|--debug] [-h|-?|--help] [--noudevsync]
[--ignoremonitoring] [--monitor {y|n}] [-i|--stripes Stripes [-I|--stripesize StripeSize]]
{[-l|--extents LogicalExtentsNumber[%{VG|PVS|FREE}] | -L|--size
LogicalVolumeSize[bBsSkKmMgGtTpPeE]] | -V|--virtualsize VirtualSize[bBsSkKmMgGtTpPeE]}
[-M|--persistent {y|n}] [--minor minor] [-m|--mirrors Mirrors [--nosync] [--mirrorlog
{disk|core|mirrored} | --corelog] [-R|--regionsize MirrorLogRegionSize]] [-n|--name
LogicalVolume{Name|Path}] [-p|--permission {r|rw}] [-r|--readahead
{ReadAheadSectors|auto|none}] [-t|--test] [-T|--thin [-c|--chunksize ChunkSize]
[--discards {ignore|nopassdown|passdown}] [--poolmetadatasize MetadataSize[bBsSkKmMgG]]]
[--thinpool ThinPoolLogicalVolume{Name|Path}] [--type SegmentType] [-v|--verbose]
[-Z|--zero {y|n}] VolumeGroup{Name|Path}[/ThinPoolLogicalVolumeName]
[PhysicalVolumePath[:PE[-PE]]...]
lvcreate [-l|--extents LogicalExtentsNumber[%{VG|FREE|ORIGIN}] | -L|--size
LogicalVolumeSize[bBsSkKmMgGtTpPeE]] [-c|--chunksize ChunkSize] [--noudevsync]
[--ignoremonitoring] [--monitor {y|n}] [-n|--name SnapshotLogicalVolume{Name|Path}]
-s|--snapshot {[VolumeGroup{Name|Path}/]OriginalLogicalVolumeName -V|--virtualsize
VirtualSize[bBsSkKmMgGtTpPeE]}
DESCRIPTION
lvcreate creates a new logical volume in a volume group (see vgcreate(8), vgchange(8)) by
allocating logical extents from the free physical extent pool of that volume group. If
there are not enough free physical extents then the volume group can be extended (see
vgextend(8)) with other physical volumes or by reducing existing logical volumes of this
volume group in size (see lvreduce(8)). If you specify one or more PhysicalVolumes,
allocation of physical extents will be restricted to these volumes.
The second form supports the creation of snapshot logical volumes which keep the contents
of the original logical volume for backup purposes.
OPTIONS
See lvm(8) for common options.
-a, --activate {y|ay|n|ey|en|ly|ln}
Controls the availability of the Logical Volumes for immediate use after the
command finishes running. By default, new Logical Volumes are activated (-ay). If
it is possible technically, -an will leave the new Logical Volume inactive. But for
example, snapshots can only be created in the active state so -an cannot be used
with --snapshot. Normally the --zero n argument has to be supplied too because
zeroing (the default behaviour) also requires activation. If autoactivation option
is used (-aay), the logical volume is activated only if it matches an item in the
activation/auto_activation_volume_list set in lvm.conf. For autoactivated logical
volumes, --zero n is always assumed and it can't be overridden. If clustered
locking is enabled, -aey will activate exclusively on one node and -aly will
activate only on the local node.
-c, --chunksize ChunkSize
Gives the size of chunk for snapshot and thin pool logical volumes. For snapshots
the value must be power of 2 between 4KiB and 512KiB and the default value is 4.
For thin pools the value must be between 64KiB and 1048576KiB and the default value
starts with 64 and scales up to fit the pool metadata size within 128MB, if the
poolmetadata size is not specified. Older dm thin pool target version (<1.4)
requires the value to be power of 2. The newer version requires to be the multiple
of 64KiB, however discard is not supported for non power of 2 values. Default unit
is in kilobytes.
-C, --contiguous {y|n}
Sets or resets the contiguous allocation policy for logical volumes. Default is no
contiguous allocation based on a next free principle.
--discards {ignore|nopassdown|passdown}
Set discards behavior. Default is passdown.
-i, --stripes Stripes
Gives the number of stripes. This is equal to the number of physical volumes to
scatter the logical volume.
-I, --stripesize StripeSize
Gives the number of kilobytes for the granularity of the stripes.
StripeSize must be 2^n (n = 2 to 9) for metadata in LVM1 format. For metadata in
LVM2 format, the stripe size may be a larger power of 2 but must not exceed the
physical extent size.
-l, --extents LogicalExtentsNumber[%{VG|PVS|FREE|ORIGIN}]
Gives the number of logical extents to allocate for the new logical volume. The
number can also be expressed as a percentage of the total space in the Volume Group
with the suffix %VG, as a percentage of the remaining free space in the Volume
Group with the suffix %FREE, as a percentage of the remaining free space for the
specified PhysicalVolume(s) with the suffix %PVS, or (for a snapshot) as a
percentage of the total space in the Origin Logical Volume with the suffix %ORIGIN.
-L, --size LogicalVolumeSize[bBsSkKmMgGtTpPeE]
Gives the size to allocate for the new logical volume. A size suffix of K for
kilobytes, M for megabytes, G for gigabytes, T for terabytes, P for petabytes or E
for exabytes is optional.
Default unit is megabytes.
--minor minor
Set the minor number.
-M, --persistent {y|n}
Set to y to make the minor number specified persistent.
-m, --mirrors Mirrors
Creates a mirrored logical volume with Mirrors copies. For example, specifying "-m
1" would result in a mirror with two-sides; that is, a linear volume plus one copy.
Specifying the optional argument --nosync will cause the creation of the mirror to
skip the initial resynchronization. Any data written afterwards will be mirrored,
but the original contents will not be copied. This is useful for skipping a
potentially long and resource intensive initial sync of an empty device.
The optional argument --mirrorlog specifies the type of log to be used. The
default is disk, which is persistent and requires a small amount of storage space,
usually on a separate device from the data being mirrored. Using core means the
mirror is regenerated by copying the data from the first device again each time the
device is activated, for example, after every reboot. Using "mirrored" will create
a persistent log that is itself mirrored.
The optional argument --corelog is equivalent to --mirrorlog core.
-n, --name LogicalVolume{Name|Path}
The name for the new logical volume.
Without this option a default names of "lvol#" will be generated where # is the LVM
internal number of the logical volume.
--noudevsync
Disable 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 LVM2 creates.
--monitor {y|n}
Start or avoid monitoring a mirrored or snapshot logical volume with dmeventd, if
it is installed. If a device used by a monitored mirror reports an I/O error, the
failure is handled according to mirror_image_fault_policy and
mirror_log_fault_policy set in lvm.conf.
--ignoremonitoring
Make no attempt to interact with dmeventd unless --monitor is specified.
-p, --permission {r|rw}
Set access permissions to read only or read and write.
Default is read and write.
--poolmetadatasize MetadataSize[bBsSkKmMgG]
Set the size of thin pool's metadata logical volume. Supported value is in range
between 2MiB and 16GiB. Default value is (Pool_LV_size / Pool_LV_chunk_size *
64b). Default unit is megabytes.
-r, --readahead {ReadAheadSectors|auto|none}
Set read ahead sector count of this logical volume. For volume groups with
metadata in lvm1 format, this must be a value between 2 and 120. The default value
is "auto" which allows the kernel to choose a suitable value automatically. "None"
is equivalent to specifying zero.
-R, --regionsize MirrorLogRegionSize
A mirror is divided into regions of this size (in MB), and the mirror log uses this
granularity to track which regions are in sync.
-s, --snapshot OriginalLogicalVolume{Name|Path}
Create a snapshot logical volume (or snapshot) for an existing, so called original
logical volume (or origin). Snapshots provide a 'frozen image' of the contents of
the origin while the origin can still be updated. They enable consistent backups
and online recovery of removed/overwritten data/files. Thin snapshot is created
when the origin is a thin volume and the size is not specified. Thin snapshot
shares same blocks within the thin pool volume. The snapshot with the specified
size does not need the same amount of storage the origin has. In a typical
scenario, 15-20% might be enough. In case the snapshot runs out of storage, use
lvextend(8) to grow it. Shrinking a snapshot is supported by lvreduce(8) as well.
Run lvdisplay(8) on the snapshot in order to check how much data is allocated to
it. Note that a small amount of the space you allocate to the snapshot is used to
track the locations of the chunks of data, so you should allocate slightly more
space than you actually need and monitor the rate at which the snapshot data is
growing so you can avoid running out of space.
-T, --thin, --thinpool ThinPoolLogicalVolume{Name|Path}
Creates thin pool or thin logical volume or both. Specifying the optional argument
--size will cause the creation of the thin pool logical volume. Specifying the
optional argument --virtualsize will cause the creation of the thin logical volume
from given thin pool volume. Specifying both arguments will cause the creation of
both thin pool and thin volume using this pool. Requires device mapper kernel
driver for thin provisioning from kernel 3.2 or newer.
--type SegmentType
Create a logical volume that uses the specified segment type (e.g. "raid5",
"mirror", "snapshot", "thin", "thin-pool"). Many segment types have a commandline
switch alias that will enable their use (-s is an alias for --type snapshot).
However, this argument must be used when no existing commandline switch alias is
available for the desired type, as is the case with error, zero, raid1, raid4,
raid5 or raid6.
-V, --virtualsize VirtualSize[bBsSkKmMgGtTpPeE]
Create a sparse device of the given size (in MB by default) using a snapshot or
thinly provisioned device when thin pool is specified. Anything written to the
device will be returned when reading from it. Reading from other areas of the
device will return blocks of zeros. Virtual snapshot is implemented by creating a
hidden virtual device of the requested size using the zero target. A suffix of
_vorigin is used for this device.
-Z, --zero {y|n}
Controls zeroing of the first KB of data in the new logical volume.
Default is yes.
Volume will not be zeroed if read only flag is set.
Snapshot volumes are zeroed always.
Warning: trying to mount an unzeroed logical volume can cause the system to hang.
Examples
Creates a striped logical volume with 3 stripes, a stripesize of 8KB and a size of 100MB
in the volume group named vg00. The logical volume name will be chosen by lvcreate:
lvcreate -i 3 -I 8 -L 100M vg00
Creates a mirror logical volume with 2 sides with a useable size of 500 MiB. This
operation would require 3 devices (or option --alloc anywhere) - two for the mirror
devices and one for the disk log:
lvcreate -m1 -L 500M vg00
Creates a mirror logical volume with 2 sides with a useable size of 500 MiB. This
operation would require 2 devices - the log is "in-memory":
lvcreate -m1 --mirrorlog core -L 500M vg00
Creates a snapshot logical volume named /dev/vg00/snap which has access to the contents of
the original logical volume named /dev/vg00/lvol1 at snapshot logical volume creation
time. If the original logical volume contains a file system, you can mount the snapshot
logical volume on an arbitrary directory in order to access the contents of the filesystem
to run a backup while the original filesystem continues to get updated:
lvcreate --size 100m --snapshot --name snap /dev/vg00/lvol1
Creates a sparse device named /dev/vg1/sparse of size 1TiB with space for just under
100MiB of actual data on it:
lvcreate --virtualsize 1T --size 100M --snapshot --name sparse vg1
Creates a linear logical volume "vg00/lvol1" using physical extents /dev/sda:0-7 and
/dev/sdb:0-7 for allocation of extents:
lvcreate -L 64M -n lvol1 vg00 /dev/sda:0-7 /dev/sdb:0-7
Creates a 5GiB RAID5 logical volume "vg00/my_lv", with 3 stripes (plus a parity drive for
a total of 4 devices) and a stripesize of 64KiB:
lvcreate --type raid5 -L 5G -i 3 -I 64 -n my_lv vg00
Creates 100MiB pool logical volume for thin provisioning build with 2 stripes 64KiB and
chunk size 128KiB together with 1TiB thin provisioned logical volume "vg00/thin_lv":
lvcreate -i 2 -I 64 -c 256 -L100M -T vg00/pool -V 1T --name thin_lv
SEE ALSO
lvm(8), vgcreate(8), lvchange(8), lvremove(8), lvrename(8) lvextend(8), lvreduce(8),
lvdisplay(8), lvscan(8)