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 lvchange(1M)							lvchange(1M)




 NAME
      lvchange - change LVM logical volume characteristics

 SYNOPSIS
      /usr/sbin/lvchange [-a availability] [-A autobackup]
	   [-c mirror_consistency] [-C contiguous]
	   [-d schedule] [-D distributed] [-M mirror_write_cache]
	   [-p permission] [-r relocate] [-s strict]
	   [-t IO_timeout] lv_path

    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.

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

 DESCRIPTION
      The lvchange command changes certain characteristics of a logical
      volume.  Other characteristics can be changed with the lvextend and
      lvreduce commands (see lvextend(1M) and lvreduce(1M)).

      The command-line options specify the type and extent of change.  Each
      current characteristic for a logical volume remains in effect until
      explicitly changed by the corresponding option.  All options take
      effect immediately, except -s, which takes effect only when new
      extents are allocated by the lvextend command.

      If a logical volume is striped, its scheduling policy is always
      parallel and its allocation policy is always strict and noncontiguous;
      these attributes cannot be changed with lvchange.

      The lvchange command can also be used to change the timeout value for
      a logical volume.	 This can be useful to control how long an IO
      request will be retried (for a transient error, like a device
      timeout), before giving up and declaring a pending IO to be failed.
      The default behavior is for the system to continue to retry an IO for
      a transient error until the IO can complete. Thus, the IO will not be
      returned to the caller until the IO can complete. By setting a non-
      zero IO timeout value, this will set the maximum length of time that
      the system will retry an IO. If the IO cannot complete before the
      length of time specified by the IO timeout, then the IO will be
      returned to the caller with an error. The actual duration of the IO
      request may exceed the logical volume's maximum IO timeout value when
      the underlying physical volume(s) have timeouts which either exceed
      the logical volume's timeout value or are not an integer multiple of
      the logical volume's timeout value (see pvchange(1M) for details on
      how to change the IO timeout value on a physical volume).





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 lvchange(1M)							lvchange(1M)




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

      lvchange recognizes the following options and arguments:

	   lv_path		    The block device path name of a logical
				    volume.

	   -a availability	    Set logical volume availability.
				    availability can have one of the
				    following values:

				    y	 Make a logical volume available.
					 An open of the logical volume will
					 succeed.

				    n	 Make a logical volume temporarily
					 unavailable.  An open of the
					 logical volume will fail.  However,
					 all current processes that have the
					 logical volume open remain open.

	   -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 or previously set.
				    mirror_consistency can have one of the
				    following values:

				    y	 Set mirror consistency recovery on.
					 LVM achieves mirror consistency
					 during volume group activation by
					 going through all logical extents
					 and copying data from a nonstale



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					 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.
				    contiguous can have one of the following
				    values:

				    y	 Set a contiguous allocation policy.
					 Physical extents are allocated in
					 ascending order without any gap
					 between adjacent extents and all
					 extents are contained in a single
					 physical volume.

				    n	 Do not set a contiguous allocation
					 policy.

				    A nonempty logical volume that has a
				    noncontiguous allocation policy cannot
				    be changed to a contiguous allocation
				    policy unless it happens to meet all the
				    requirements of the contiguous
				    allocation policy.	See lvcreate(1M) for
				    more information about the contiguous
				    allocation policy.

	   -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.

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

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





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				    y	 Turn on distributed allocation.

				    n	 Turn off distributed allocation.

				    f	 Force distributed allocation to be
					 on.

				    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
				    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.

				    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).

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

				    See lvcreate(1M) for more information on
				    the distributed allocation policy.

				    The -D y option will fail if the
				    existing logical volume has any two
				    consecutive logical extents on the same
				    physical volume.  To override this
				    failure, use the -D f option.

				    If a logical volume with the distributed
				    allocation policy has at least two
				    consecutive logical extents on the same
				    physical volume, then lvdisplay(1M) will
				    display the allocation as partially-
				    distributed (vs.  distributed).





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				    See lvdisplay(1M) for display values.

	   -M mirror_write_cache    Set the Mirror Write Cache flag.  This
				    option is allowed only when the logical
				    volume is not opened.
				    mirror_write_cache can have one of the
				    following values:

				    y	 Set Mirror Write Cache on.  Every
					 write to a mirror copy is recorded
					 in the Mirror Write Cache and
					 written into the Mirror Consistency
					 Record on the disk if a cache-miss
					 occurs.  This allows LVM to
					 determine whether all mirror 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 off.  Mirror
					 write does not incur an additional
					 write to the Mirror Consistency
					 Record on the disk.

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

				    w	 Set the access permission to read-
					 write.

				    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



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					 error will be returned, and
					 subsequent I/O requests containing
					 the bad block will again attempt
					 relocation.

				    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
					 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.  This option only makes sense
				    when the physical volumes of the volume
				    group that owns the specified logical
				    volume reside on different physical
				    disks.  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.

				    g	 Set a PVG-strict allocation policy.
					 Mirrors of a logical extent cannot
					 share the same physical volume
					 group.

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



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 lvchange(1M)							lvchange(1M)




				    When a logical volume is mirrored, the
				    following changes are not allowed:

				    +	 From nonstrict to strict
				    +	 From nonstrict to PVG-strict
				    +	 From strict to PVG-strict

	   -t IO_timeout	    Set the IO_timeout for the logical
				    volume to the number of seconds
				    indicated. This value will be used to
				    determine how long to wait for IO
				    requests to complete before concluding
				    that an IO request cannot be completed.
				    An IO_timeout value of zero (0) causes
				    the system to use the default value of
				    "forever".	NOTE: The actual duration of
				    the request may exceed the specified
				    IO_timeout value when the underlying
				    physical volume(s) have timeouts which
				    either exceed this IO_timeout value or
				    are not integer multiples of this value.

 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
      Change the permission of a logical volume to read-only:

	   lvchange -p r /dev/vg01/lvol3

      Change the allocation policy of a logical volume to nonstrict:

	   lvchange -s n /dev/vg01/lvol7

      Turn the mirror write cache off on a logical volume:

	   lvchange -M n /dev/vg01/lvol1

      Change the IO timeout value of a logical volume to 1 minute (60
      seconds):

	   lvchange -t 60 /dev/vg01/lvol1

 WARNINGS
      For root, swap or dump logical volumes, the allocation policy is



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 lvchange(1M)							lvchange(1M)




      always contiguous.  This attribute cannot be changed with lvchange.

 SEE ALSO
      lvcreate(1M), lvdisplay(1M), lvextend(1M).


















































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