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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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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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 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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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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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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always contiguous. This attribute cannot be changed with lvchange.
SEE ALSO [Toc] [Back]
lvcreate(1M), lvdisplay(1M), lvextend(1M).
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