Visit Our UNIX and Linux User Community

Linux and UNIX Man Pages

Test Your Knowledge in Computers #564
Difficulty: Medium
The negation operator is a null task operator not a unary operator.
True or False?
Linux & Unix Commands - Search Man Pages

lvcreate(8) [bsd man page]

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|--available	{y|n|ey|en|ly|ln}] [-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  Virtual-
       Size[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 {ReadAhead-
       Sectors|auto|none}] [-t|--test] [-T|--thin [-c|--chunksize ChunkSize] [--poolmetadatasize MetadataSize[bBsSkKmMgG]]] [--thinpool  ThinPool-
       LogicalVolume{Name|Path}]  [--type SegmentType] [-v|--verbose] [-Z|--zero {y|n}] VolumeGroup{Name|Path}[/ThinPoolLogicalVolumeName] [Physi-
       calVolumePath[: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   {[Vol-
       umeGroup{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 physi-
       cal  extent  pool  of  that  volume group.  If there are not enough free physical extents then the volume group can be extended ( see vgex-
       tend(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 pur-
       poses.

OPTIONS
       See lvm(8) for common options.

       -a, --available {y|n|ey|en|ly|ln}
	      Controls the availability of the Logical Volumes for immediate use after the command finishes running.  By default, new Logical Vol-
	      umes  are  activated  automatically  (-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 clustered locking is enabled, -aey will
	      activate exclusively on one node and -aly will activate only on the local node.

       -c, --chunksize ChunkSize
	      Power of 2 chunk size in sector units (512b).  For snapshot logical volume the value must be between 8 (4KB) and	1024  (512KB)  and
	      the  default  value is 8.  For thin pool logical volume the value must be between 128 (64KB) and 2097152 (1MB) and the default value
	      is 128.

       -C, --contiguous {y|n}
	      Sets or resets the contiguous allocation policy for logical volumes. Default is no contiguous allocation based on a next free  prin-
	      ciple.

       -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  regener-
	      ated  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 cre-
	      ates.

       --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 recov-
	      ery  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  grow-
	      ing 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  seg-
	      ment  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 speci-
	      fied.  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  vol-
       ume 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-mem-
       ory".

       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 1TB with space for just under 100MB 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  provi-
       sioned 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), lvremove(8), lvrename(8) lvextend(8), lvreduce(8), lvdisplay(8), lvscan(8)

Sistina Software UK					 LVM TOOLS 2.02.95(2) (2012-03-06)					       LVCREATE(8)

Featured Tech Videos