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LVCREATE(8)                 System Manager's Manual                LVCREATE(8)



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[%{VG|PVS|FREE}] |
        -L|--size LogicalVolumeSize[kKmMgGtT]} [-M|--persistent y|n]
       [--minor minor] [-m|--mirrors Mirrors [--nosync] [--mirrorlog
       {disk|core}] [--corelog] [-R|--regionsize MirrorLogRegionSize]]
       [-n|--name LogicalVolumeName] [-p|--permission r|rw] [-r|--readahead
       ReadAheadSectors|auto|none] [-t|--test] [-v|--verbose] [-Z|--zero y|n]
       VolumeGroupName [PhysicalVolumePath...]

       lvcreate {-l|--extents LogicalExtentsNumber[%{VG|FREE}] |
        -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) 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}]
              Gives the number of logical extents to allocate for the new
              logical volume.  This can also be expressed as a percentage of
              the total space in the Volume Group with the suffix %VG, of the
              remaining free space in the Volume Group with the suffix %FREE,
              or of the remaining free space for the specified
              PhysicalVolume(s) with the suffix %PVS,

       -L, --size LogicalVolumeSize[kKmMgGtTpPeE]
              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.

              The optional argument --corelog is equivalent to --mirrorlog
              core.


       -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|rw
              Set access permissions to read only or read and write.
              Default is read and write.

       -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
              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.
              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
       "lvcreate -i 3 -I 8 -L 100M 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 -m1 -L 500M vg00" tries to create a mirror logical volume
       with 2 sides with a useable size of 500 MiB.  This operation would
       require 3 devices - two for the mirror devices and one for the disk
       log.

       "lvcreate -m1 --mirrorlog core -L 500M vg00" tries to create 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 --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)



Sistina Software UK    LVM TOOLS 2.02.44-cvs (02-17-09)            LVCREATE(8)