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).
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 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:
- 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).
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 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.
When a logical volume is mirrored,
the following changes are not allowed:
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 always contiguous. This
attribute cannot be changed with
lvchange.
DEPENDENCIES
The
-r
option is not available on HP-IB devices.
