lvcreate(8) -- Linux man page

 

NAME

lvcreate - create a logical volume in an existing volume group  

SYNOPSIS

lvcreate [--addtag Tag] [--alloc AllocationPolicy] [-A/--autobackup y/n] [-C/--contiguous y/n] [-d/--debug] [-h/-?/--help] [-i/--stripes Stripes [-I/--stripesize StripeSize]] {-l/--extents LogicalExtentsNumber |
 -L/--size LogicalVolumeSize[kKmMgGtT]} [-M/--persistent y/n] [--minor minor] [-n/--name LogicalVolumeName] [-p/--permission r/rw] [-r/--readahead ReadAheadSectors] [-t/--test] [-v/--verbose] [-Z/--zero y/n] VolumeGroupName [PhysicalVolumePath...]


lvcreate {-l/--extents LogicalExtentsNumber |
 -L/--size LogicalVolumeSize[kKmMgGtT]} [-c/--chunksize ChunkSize] -s/--snapshot -n/--name SnapshotLogicalVolumeName OriginalLogicalVolumePath  

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) ).
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 for common options.
-c, --chunksize ChunkSize
Power of 2 chunk size for the snapshot logical volume between 4k and 512k.
-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.
-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)
-l, --extents LogicalExtentsNumber
Gives the number of logical extents to allocate for the new logical volume.
-L, --size LogicalVolumeSize[kKmMgGtT]
Gives the size to allocate for the new logical volume. A size suffix of K for kilobytes, M for megabytes, G for gigabytes or T for terabytes 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.
-n, --name LogicalVolumeName
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.
-p, --permission r/w
Set access permissions to read only or read and write.
Default is read and write.
-r, --readahead ReadAheadSectors
Set read ahead sector count of this logical volume to a value between 2 and 120. Ignored by device-mapper.
-s, --snapshot
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. The snapshot 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.
-Z, --zero y/n
Controls zeroing of the first KB of data in the new logical volume.
Default is yes.


Warning: trying to mount an unzeroed logical volume can cause the system to hang.

 

Examples

"lvcreate -i 3 -I 8 -L 100 vg00" tries to create 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 --size 100m --snapshot --name snap /dev/vg00/lvol1"
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.

 

SEE ALSO

lvm(8), vgcreate(8), lvremove(8), lvrename(8) lvextend(8), lvreduce(8), lvdisplay(8), lvscan(8)