NAME
pvchange — change characteristics and access path of a physical volume in an LVM volume group
SYNOPSIS
/usr/sbin/pvchange
[-A
autobackup]
-a
availability
pv_path
/usr/sbin/pvchange
[-A
autobackup]
-s
pv_path
/usr/sbin/pvchange
[-A
autobackup]
-S
autoswitch
pv_path
/usr/sbin/pvchange
[-A
autobackup]
-x
extensibility
pv_path
/usr/sbin/pvchange
[-A
autobackup]
-t
IO_timeout
pv_path
/usr/sbin/pvchange
[-A
autobackup]
-z
sparepv
pv_path
/usr/sbin/pvchange
[-A
autobackup]
-p
proactivepolling
pv_path
Remarks
Only
pvchange
-a
can be performed if the volume group is activated in shared mode.
All other options are not allowed for physical volumes in shared volume groups.
DESCRIPTION
The
pvchange
command changes the characteristics and access path of a physical volume
(pv_path)
in a volume group.
For multiported devices accessed through multiple paths, you can use
pvchange
to customize the following behaviors:
How LVM switches from one path to another in case of path failure or recovery.
How LVM tests alternate links.
pvchange
also permits you to switch manually to a specific
path to the physical volume.
pvchange
sets the allocation permission to add physical extents to the physical volume.
If you have installed the optional HP MirrorDisk/UX software, you
can use the
-z
option to designate a spare physical volume to be used to replace
an existing physical volume within a volume group when mirroring
is in effect, in the event the
existing physical volume fails.
pvchange
can also be used to
attach
or
detach
specific paths or physical volumes.
Options and Arguments
pvchange
recognizes the following options and arguments.
- pv_path
The block device path name of a physical volume.
- -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.
- -a availability
Attach or detach the physical volume
pv_path.
availability
can have one of the following values:
- y
Attach the indicated path to the physical volume.
An
attached
path or device is available for LVM to use.
Attaching a path makes that path available to the volume group, if possible.
LVM may begin using the path if necessary to access the disk.
If formerly all the paths were unavailable to a given physical volume,
making any path available will make the physical volume available again.
- n
Detach
only
the indicated path to the physical volume. A
detached
path is not available for LVM to use.
Detaching a single path causes LVM to close the device for that one path
and to stop using it.
If the path is the primary path to the device,
LVM will begin using the best alternate path to the device that is available.
When the only path to a device is detached, the associated physical volume
will be unavailable to the volume group. The path remains part of the
volume group but no I/O is queued to it and the path will remain unused by LVM
until it is reattached.
LVM will only stop using the physical volume when
all
the paths to the physical volume are detached.
Individually detaching all the paths to a physical volume has
the same consequences as detaching the physical volume entirely using the
-a N
option.
The system administrator may safely diagnose or replace hardware along the
path detached, but care should be taken to avoid accessing the PV
if it is still being accessed by LVM via other active paths to it.
- N
Detach the given path and all other paths to the physical volume.
The system administrator should always presume that all the disks
that belong to an active volume group are attached and may be
used by LVM at any time, unless LVM has been specifically notified
to detach them.
Prior to replacing or repairing any disk
belonging to an active volume group, the administrator must
first detach the PV using this command.
When a PV is detached, LVM closes all the paths to the PV
and no longer directs any I/O operations to it.
If a suitable spare PV is available in the volume group,
LVM will use it to reconstruct the detached disk.
The given path must be an attached path to the PV, otherwise,
the command will fail and display an error message indicating
the problem. If for any reason the use of the
-a N
opton fails, the physical volume can still be detached from the volume group
by individually detaching each of the paths to the physical volume
using the
-a n
option instead.
- -s
Immediately begin accessing the associated physical volume named by
pv_path.
- -S autoswitch
This option specifies the
autoswitch
behavior for multiported physical volumes accessed through multiple paths.
It has no effect for physical volumes without alternate paths.
autoswitch
can have one of the following values:
- y
LVM is directed to automatically switch from the path it is using whenever a
better path to the physical volume is available.
LVM will switch paths when a better path recovers (after it had
failed earlier), or if the current path fails and another path is available.
This is the default.
- n
LVM is directed to automatically switch to using the best available path only
when the path currently in use is unavailable.
LVM will continue using a specific path for the physical volume
as long as it works, regardless of whether another better path
recovers from a failure.
- -x extensibility
Set the allocation permission to add physical extents to the physical volume
pv_path.
extensibility
can have one of the following values:
- y
Allow allocation of additional physical extents on the physical volume.
This is the default.
- n
Prohibit allocation of additional physical extents on the physical volume.
However, logical volumes residing on the physical volume are accessible.
- -t IO_timeout
Set
IO_timeout
for the physical volume to the number of seconds indicated. An
IO_timeout
value of zero (0) causes the system to use the default value supplied
by the device driver associated with the physical device.
IO_timeout
is used by the device driver to determine how long to wait for disk
transactions to complete before concluding that an IO request
can not be completed (and the device is offline or unavailable).
- -z sparepv
This option requires the installation of the optional HP MirrorDisk/UX
software. It allows you to change the physical volume specified by
pv_path
into a spare physical volume for its
volume group, or change the specified spare physical volume back into a regular
physical volume for this volume group. No physical extents from
a spare physical volume will be available as part of the "free" pool of
extents in the volume group. A spare physical volume will only be used
in the event that another physical volume within this volume group
becomes unavailable (fails).
sparepv
can have one of the following values:
- y
Change the specified physical volume to be a "stand-by" spare for its
volume group. The specified physical volume must not have extents
allocated on it (i.e., no logical
volumes residing on it) at the time this command is
issued. A stand-by spare physical volume will only be
used in the event of a failure of another physical volume -- prior
to such a failure, no
logical volume is allowed to reside on it.
- n
Change the specified spare physical volume back into a regular physical volume.
If the physical volume was a stand-by spare, then all of the
disk space associated with it will be immediately available for use by
logical volumes. If the physical volume is an "active" spare, that is,
it was previously a stand-by spare but then took over for a
failed physical volume, it will
simply mark the physical volume as a regular member of its volume group
and the logical volumes residing on it will remain unchanged.
- -p proactivepolling
(See
WARNINGS
section). This option specifies LVM's
proactive polling behavior on alternate links.
proactivepolling
can have one of the following values:
- y
Enable LVM's proactive polling for alternate links of a physical
volume. LVM will periodically test alternate links.
This is the default.
- n
Disable LVM's proactive polling for alternate links of a physical volume.
LVM will not periodically test alternate links.
Special notes regarding attaching and detaching physical volumes
Detaching a physical volume makes the data on that disk unavailable.
LVM will not write or read any user data or LVM metadata to the disk
while it is detached. Consequently, it is important for the
administrator to ensure that the data on the disk is sufficiently
mirrored to satisfy availability requirements prior to making
the device unavailable by detaching it.
Although detaching a path or PV ensures it is unavailable to LVM,
attaching a path or PV will not necessarily make the path or PV available
again. Attaching a path or PV only makes it available for LVM to use once the
disk is working. For instance, if a disk is spinning up, LVM
will successfully attach the disk, but the disk will not be available until
it is ready.
Detaching a PV or path only temporarily changes the status
of the indicated path or physical volume. However, it does not change the
volume group configuration. When a physical volume is detached, it will
automatically be attached again the next time the volume group is activated
using the
vgchange(1M)
command.
If the objective is to permanently add or remove a path or PV from the volume
group, the
vgextend(1M)
or
vgreduce(1M)
commands should be used instead.
Warning: Detaching any PV or path using the
-a N
or
-a n
options also disables automatically attaching
any
paths to any of the physical volumes in the volume group.
LVM will no longer attempt to automatically recover any unattached
physical volumes in the volume group, not just the ones explicitly detached.
To cause LVM to once again automatically attach devices in the volume group
use the
vgchange -a y
command.
Special notes for attaching or detaching physical volumes in Shared Volume Groups
The scope of the
pvchange(1M)
command is limited to the specific node it is run on.
Systems that are part of a Serviceguard cluster operate independently.
To replace disks that are part of a volume group shared by a Serviceguard cluster,
the PV must be detached and attached independently on each of the systems in the cluster.
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
Prohibit the allocation of additional physical extents to a physical volume:
pvchange -x n /dev/dsk/c0t0d0
Allow the allocation of additional physical extents to a physical volume:
pvchange -x y /dev/dsk/c0t0d0
Only switch paths when the current path is unavailable. Do not
switch back to a prior path which had failed and has recovered,
when the current path works:
pvchange -S n /dev/dsk/c0t0d0
Switch paths whenever a better path becomes available again after a
failure, even if the current path is fine:
pvchange -S y /dev/dsk/c0t0d0
Manually switch a physical volume to use another controller path:
pvchange -s /dev/dsk/c2t0d2
Set the
IO_timeout
value
for a physical volume to 60 seconds:
pvchange -t 60 /dev/dsk/c2t0d2
Set the
IO_timeout
value
for a physical volume to zero (0) to use the driver default:
pvchange -t 0 /dev/dsk/c2t0d2
Change the (empty) physical volume to become a stand-by spare for the volume
group:
pvchange -z y /dev/dsk/c2t0d2
Change the (active or stand-by) spare physical volume to become a regular
member of the volume group:
pvchange -z n /dev/dsk/c2t0d2
Enable LVM's proactive polling of alternate links
pvchange -p y /dev/dsk/c2t0d2
Disable LVM's proactive polling of alternate links
pvchange -p n /dev/dsk/c2t0d2
Detach a path to a PV
pvchange -a n /dev/dsk/c2t0d2
Detach all the paths to a PV
pvchange -a N /dev/dsk/c2t0d2
Attach a path to a PV.
pvchange -a y /dev/dsk/c2t0d2
The
vgchange(1M)
command may be used to attach all PVs in the volume group
and resume automatically attaching failed PVs.
vgchange -a y /dev/vg_work
WARNINGS
The
-p
proactivepolling
option requires the kernel to be updated to support this functionality.