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 lvchange(1M)                                                   lvchange(1M)




 NAME    [Toc]    [Back]
      lvchange - change LVM logical volume characteristics

 SYNOPSIS    [Toc]    [Back]
      /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    [Toc]    [Back]
      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    [Toc]    [Back]
      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 nonzero
 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    [Toc]    [Back]
      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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 lvchange(1M)                                                   lvchange(1M)




                                         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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 lvchange(1M)                                                   lvchange(1M)




                                    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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 lvchange(1M)                                                   lvchange(1M)




                                    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 readwrite.


                                    r    Set the access permission to readonly.


           -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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 lvchange(1M)                                                   lvchange(1M)




                                         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    [Toc]    [Back]
    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    [Toc]    [Back]
      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    [Toc]    [Back]
      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    [Toc]    [Back]
      lvcreate(1M), lvdisplay(1M), lvextend(1M).


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