unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (HP-UX-11.11)
Page:
Section:
Apropos / Subsearch:
optional field



 lvcreate(1M)							lvcreate(1M)




 NAME
      lvcreate - create logical volume in LVM volume group

 SYNOPSIS
      /usr/sbin/lvcreate [-A autobackup] [-c mirror_consistency]
	   [-C contiguous] [-d schedule] [-D distributed]
	   [-i stripes -I stripe_size] [-l le_number | -L lv_size]
	   [-m mirror_copies] [-M mirror_write_cache] [-n lv_name]
	   [-p permission] [-r relocate] [-s strict] vg_name

    Remarks
      Mirrored disk operations require the installation of the optional HP
      MirrorDisk/UX software, which is not included in the standard HP-UX
      operating system.

      lvcreate cannot be performed if the volume group is activated in shared
      mode.

      Logical volumes that were created using the striped option are not
      supported in shared mode.

 DESCRIPTION
      The lvcreate command creates a new logical volume within the volume
      group specified by vg_name.  Up to 255 logical volumes can be created
      in one volume group.

      If you specify the -n lv_name option, a new logical volume is created
      with that name.  Otherwise, a system-generated name of the form lvolN
      is created, where N is the decimal equivalent of the two least
      significant bytes of the minor number of the new logical volume, in
      the range 1 to 255 (see lvm(7)).	Two device files are created in
      vg_name: a block device file named lv_name or lvolN, and a character
      (raw) device file named rlv_name or rlvolN.

      If you omit the -l and -L options, the logical volume is created with
      zero length.  This permits you to choose its physical volume location
      when you allocate logical extents with the lvextend command (see
      lvextend(1M)).  If you specify -l or -L, the location is determined
      automatically.

      The default settings provide the most commonly used characteristics.
      Use the options to tailor the logical volume to the requirements of
      the system.  Once a logical volume is created, some of its
      characteristics can be changed with the lvchange, lvextend, and
      lvreduce commands (see lvchange(1M), lvextend(1M), and lvreduce(1M)).

    Options and Arguments
      The -c, -d, -m, -M, and -s options are only meaningful if the optional
      HP MirrorDisk/UX software has been installed on the system.





 Hewlett-Packard Company	    - 1 -   HP-UX Release 11i: November 2000






 lvcreate(1M)							lvcreate(1M)




      lvcreate recognizes the following options and arguments:

	   vg_name		    The path name of a volume group.

	   -A autobackup	    Set automatic backup for this invocation
				    of this command.  autobackup can have
				    one of the following values:

				    y	 Automatically back up configuration
					 changes made to the logical volume.
					 This is the default.

					 After this command executes, the
					 vgcfgbackup command (see
					 vgcfgbackup(1M)) is executed for
					 the volume group to which the
					 logical volume belongs.

				    n	 Do not back up configuration
					 changes this time.

	   -c mirror_consistency    Set mirror consistency recovery.  This
				    option is effective only when -M n is
				    specified.	It is ignored for -M y.
				    mirror_consistency can have one of the
				    following values:

				    y	 Set mirror consistency recovery on.
					 This is the default.

					 LVM achieves mirror consistency
					 during volume group activation by
					 going through all logical extents
					 and copying data from a nonstale
					 copy to the other mirror copies.

				    n	 Set mirror consistency recovery
					 off.  LVM does not perform mirror
					 consistency recovery on this
					 logical volume when the volume
					 group is activated.

	   -C contiguous	    Set the contiguous allocation policy.  A
				    contiguous logical volume has three
				    characteristics:

				    +	 Physical extents are allocated in
					 ascending order,
				    +	 No gap is allowed between physical
					 extents within a mirror copy,




 Hewlett-Packard Company	    - 2 -   HP-UX Release 11i: November 2000






 lvcreate(1M)							lvcreate(1M)




				    +	 Physical extents of any mirror copy
					 all reside on a single physical
					 volume.

				    Use the strict (-s) and contiguous (-C)
				    options together to form various
				    combined allocation policies on a
				    logical volume.  For example, -s y -C y
				    defines a logical volume such that each
				    mirror copy is contiguous, yet mirror
				    copies of a logical extent cannot share
				    the same physical volume.

				    contiguous can have one of the following
				    values:

				    y	 Set a contiguous allocation policy.

				    n	 Do not set a contiguous allocation
					 policy.  This is the default.

	   -d schedule		    Set the scheduling policy when a logical
				    extent with more than one mirror is
				    written.  (The scheduling policy of a
				    striped logical volume is striped and
				    cannot be changed.) schedule can have
				    one of the following values:

				    p	 Establish a parallel scheduling
					 policy.  This is the default.

				    s	 Establish a sequential scheduling
					 policy.  Use this value with care,
					 because it leads to performance
					 loss in most cases.

	   -D distributed	    Set the distributed allocation policy.
				    distributed can have one of the
				    following values:

				    y	 Turn on distributed allocation.

				    n	 Turn off distributed allocation.
					 This is the default.

				    When the distributed allocation policy
				    is turned on, only one free extent is
				    allocated from the first available
				    physical volume.  The next free extent
				    is allocated from the next available
				    physical volume.  Allocation of free



 Hewlett-Packard Company	    - 3 -   HP-UX Release 11i: November 2000






 lvcreate(1M)							lvcreate(1M)




				    extents proceeds in round-robin order on
				    the list of available physical volumes.

				    When the distributed allocation policy
				    is turned off, all available free
				    extents are allocated from each
				    available physical volume before
				    proceeding to the next available
				    physical volume.  This is the default.

				    The distributed allocation policy
				    REQUIRES the PVG-strict allocation
				    policy ( -s g ) to ensure that mirrors
				    of distributed extents do not overlap
				    (for maximum availability).

				    lvcreate(1M) will obtain the list of
				    available physical volumes from
				    /etc/lvmpvg.  See vgextend(1M) for more
				    information on physical volume groups
				    and /etc/lvmpvg.

				    When a logical volume with distributed
				    extents is mirrored, the resulting
				    layout is commonly referred to as
				    EXTENT-BASED MIRRORED STRIPES.

				    Note that EXTENT-BASED MIRRORED STRIPES
				    can be created without the distributed
				    allocation policy by adding one extent
				    at a time to the desired physical
				    volumes through lvextend(1M).

				    The distributed allocation policy is
				    incompatible with the striped scheduling
				    policy ( -i stripes ) and the contiguous
				    allocation policy ( -C y ).

				    The lvchange(1M) command can be used to
				    assign the distributed allocation policy
				    to an existing logical volume.

				    See lvdisplay(1M) for display values.

				    See EXAMPLES.

	   -i stripes		    Set the number of disks to stripe
				    across.  stripes must be in the range 2
				    to the number of disks in the current
				    volume group.  -i and -I must be
				    specified together.



 Hewlett-Packard Company	    - 4 -   HP-UX Release 11i: November 2000






 lvcreate(1M)							lvcreate(1M)




	   -I stripe_size	    Set the size in kilobytes of the stripe.
				    stripe_size should be a power of 2 in
				    the range 4 to 32768.  -i and -I must be
				    specified together.

	   -l le_number		    Allocate space to the logical volume,
				    specified in logical extents.  le_number
				    is a decimal value in the range 1 to
				    65535 (the implementation limit).  The
				    default is described above.

				    Either -l or -L can be specified, but
				    not both.

	   -L lv_size		    Allocate space to the logical volume,
				    specified in megabytes.  lv_size is a
				    decimal value in the range 1 to 16777216
				    (the implementation limit).	 lv_size is
				    rounded up to the nearest multiple of
				    the logical extent size, equivalent to
				    the physical extent size defined for the
				    volume group by the vgcreate command
				    (see vgcreate(1M)).	 The default is
				    described above.

				    Either the -l or the -L option can be
				    specified, but not both.

	   -m mirror_copies	    Set the number of mirror copies
				    allocated for each logical extent.	A
				    mirror copy contains the same data as
				    the original.  mirror_copies can have
				    the value 1 or 2.  The default value is
				    0 (no mirror copies).

	   -M mirror_write_cache    Set the Mirror Write Cache flag.
				    mirror_write_cache can have one of the
				    following values:

				    y	 Set Mirror Write Cache on.  This is
					 the default.

					 Every write to a mirror copy is
					 recorded in the Mirror Write Cache.
					 The Mirror Consistency Record in
					 the Volume Group Reserved Area on
					 the disk is updated whenever there
					 is a write to a logical track group
					 that is not already recorded in the
					 cache.	 This allows LVM to
					 determine whether all the mirror



 Hewlett-Packard Company	    - 5 -   HP-UX Release 11i: November 2000






 lvcreate(1M)							lvcreate(1M)




					 copies are identical, even across
					 system crashes.  When the volume
					 group is activated, the Mirror
					 Consistency Record is used to
					 perform mirror consistency
					 recovery.

				    n	 Set Mirror Write Cache to off.
					 Mirror write does not incur an
					 additional write to the Mirror
					 Consistency Record.

	   -n lv_name		    Set the name of the new logical volume
				    to lv_name, where lv_name is a simple
				    file name, not a path name.	 The default
				    is described above.

	   -p permission	    Set the access permission.	permission
				    can have one of the following values:

				    w	 Set the access permission to read-
					 write.	 This is the default.

				    r	 Set the access permission to read-
					 only.

	   -r relocate		    Set the bad block relocation policy.
				    relocate can have one of the following
				    values:

				    y	 Allow bad block relocation.  Upon a
					 media failure (detection of a bad
					 block of data on disk), LVM will
					 mark the failed block in the Bad
					 Block Directory, and attempt to
					 relocate the block to a new
					 location on disk.  If relocation is
					 successful then no error will be
					 returned, and future I/O requests
					 which contain the bad block will be
					 directed to the new location.	If
					 relocation is unsuccessful, an I/O
					 error will be returned, and
					 subsequent I/O requests containing
					 the bad block will again attempt
					 relocation.  This is the default.

				    n	 Prevent bad block relocation.	Upon
					 a media failure, LVM will mark the
					 failed block as bad in the Bad
					 Block Directory, but will NOT



 Hewlett-Packard Company	    - 6 -   HP-UX Release 11i: November 2000






 lvcreate(1M)							lvcreate(1M)




					 attempt to relocate the bad block
					 to a new location on disk. Future
					 I/O requests which contain the bad
					 block will return with an I/O
					 error.	 No attempt will be made to
					 access the bad block.

				    N	 Disable bad block relocation and
					 the Bad Block Directory.  Upon a
					 media failure, LVM will NOT attempt
					 to relocate the bad block. In
					 addition it will NOT enter the
					 block in the Bad Block Directory.
					 LVM will have no record of the
					 block being bad, and will attempt
					 to access it on future I/O
					 requests.

	   -s strict		    Set the strict allocation policy.
				    Mirror copies of a logical extent can be
				    allocated to share or not share the same
				    physical volume or physical volume
				    group.  strict can have one of the
				    following values:

				    y	 Set a strict allocation policy.
					 Mirrors of a logical extent cannot
					 share the same physical volume.
					 This is the default.

				    g	 Set a PVG-strict allocation policy.
					 Mirrors of a logical extent cannot
					 share the same physical volume
					 group.	 A PVG-strict allocation
					 policy cannot be set on a logical
					 volume in a volume group that does
					 not have a physical volume group
					 defined.

				    n	 Do not set a strict or PVG-strict
					 allocation policy.  Mirrors of a
					 logical extent can share the same
					 physical volume.

      Striped logical volumes are only allocated using the strict or PVG-
      strict allocation policies.  The number of extents for a striped
      logical volume is always a multiple of the number of disks the logical
      volume is striped across.	 A logical volume striped across n disks, is
      allocated in sets of n extents, and each extent of a given set is
      allocated on a different physical volumes in the volume group.




 Hewlett-Packard Company	    - 7 -   HP-UX Release 11i: November 2000






 lvcreate(1M)							lvcreate(1M)




 EXTERNAL INFLUENCES
    Environment Variables
      LANG determines the language in which messages are displayed.

      If LANG is not specified or is null, it defaults to "C" (see lang(5)).

      If any internationalization variable contains an invalid setting, all
      internationalization variables default to "C" (see environ(5)).

 EXAMPLES
      Create a logical volume in volume group /dev/vg02:

	   lvcreate /dev/vg02

      Create a logical volume in volume group /dev/vg03 with nonstrict
      allocation policy:

	   lvcreate -s n /dev/vg03

      Create a logical volume of size 100 MB in volume group /dev/vg03:

	   lvcreate -L 100 /dev/vg03

      Create a logical volume of size 90 MB striped across 3 disks with a
      stripe size of 64 KB:

	   lvcreate -L 90 -i 3 -I 64 /dev/vg03

    Distributed Allocation Policy
      This example shows how the -D y option can be used to create EXTENT-
      BASED MIRRORED STRIPES.

      Assume that volume group /dev/vgtest has two physical volume groups:
      pvg1, pvg2.

      Assume that each physical volume group has 2 physical volumes.

      Assume that the first physical volume in each pvg has 3 extents free
      and the second physical volume in each pvg has 2 extents free.

      The following command creates a logical volume in vgtest with EXTENT-
      BASED MIRRORED STRIPES:

	   lvcreate -D y -s g -m 1 -l 5 /dev/vgtest

      The distributed allocation proceeds as follows:
	   +	A free extent is allocated from the 1st pvol in pvg1.
	   +	A free extent is allocated from the 2nd pvol in pvg1.
	   +	A free extent is allocated from the 1st pvol in pvg1.
	   +	A free extent is allocated from the 2nd pvol in pvg1.




 Hewlett-Packard Company	    - 8 -   HP-UX Release 11i: November 2000






 lvcreate(1M)							lvcreate(1M)




	   +	A free extent is allocated from the 1st pvol in pvg1.
	   +	Mirrors for the five extents are then allocated from the
		free extents in pvg2 in a similar manner.

 WARNINGS
      The root, swap, and dump logical volumes (see lvlnboot(1M)) must be
      created with contiguous allocation policy.

 SEE ALSO
      lvchange(1M), lvdisplay(1M), lvextend(1M), lvreduce(1M), pvchange(1M).












































 Hewlett-Packard Company	    - 9 -   HP-UX Release 11i: November 2000