pvchange(1M)pvchange(1M)NAMEpvchange - change characteristics and access path of a physical volume
in an LVM volume group
SYNOPSIS
autobackup] availability pv_path
autobackup] pv_path
autobackup] autoswitch pv_path
autobackup] extensibility pv_path
autobackup] IO_timeout pv_path
autobackup] sparepv pv_path
autobackup] proactivepolling pv_path
Remarks
Only 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 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 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.
also permits you to switch manually to a specific path to the physical
volume.
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 option to designate a spare physical volume to be used to
replace an existing physical volume within a volume group when mirror‐
ing is in effect, in the event the existing physical volume fails.
can also be used to attach or detach specific paths or physical volumes
(see WARNINGS section).
Options and Arguments
recognizes the following options and arguments.
pv_path The block device path name of a physical
volume.
Set automatic backup for this invocation of this command.
autobackup can have one of the following
values:
Automatically back up configuration changes
made to the logical volume.
This is the default.
After this command executes, the com‐
mand (see vgcfgbackup(1M)) is exe‐
cuted for the volume group to which
the logical volume belongs.
Do not back up configuration changes this
time.
Attach or detach the physical volume
pv_path. availability can have one of the
following values:
Attach the indicated path to the physical
volume.
An attached path or device is avail‐
able 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 vol‐
ume available again.
(See WARNINGS section). Detach only the
indicated path to the physical vol‐
ume. A detached path is not avail‐
able 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 option. The sys‐
tem administrator may safely diagnose
or replace hardware along the path
detached, but care should be taken to
avoid accessing the physical volume
if it is still being accessed by LVM
via other active paths to it.
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 physical volume using this
command.
When a physical volume is detached,
LVM closes all the paths to the phys‐
ical volume and no longer directs any
I/O operations to it. If a suitable
spare physical volume 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 physical volume; otherwise,
the command will fail and display an
error message indicating the problem.
If for any reason the use of the
option 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 option instead.
(See WARNINGS section). Immediately begin
accessing the associated physical volume
named by pv_path.
(See WARNINGS section). This option specifies
the autoswitch behavior for multiported
physical volumes accessed through multiple
paths. It has no effect for physical vol‐
umes without alternate paths. autoswitch
can have one of the following values:
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 cur‐
rent path fails and another path is
available. This is the default.
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 vol‐
ume as long as it works, regardless
of whether another better path recov‐
ers from a failure.
Set the allocation permission to add physical extents to the
physical volume
pv_path. extensibility can have one of the
following values:
Allow allocation of additional physical
extents on the physical volume.
This is the default.
Prohibit allocation of additional physical
extents on the physical volume.
However, logical volumes residing on
the physical volume are accessible.
Set the I/O timeout value for the physical volume, to the number
of
seconds indicated. An I/O timeout value of
zero (0) causes the system to use the
default value supplied by the device driver
associated with the physical device. I/O
timeout value is used by the device driver
to determine how long to wait for disk
transactions to complete before concluding
that an I/O request can not be completed
(and the device is offline or unavailable).
This option is only applicable for physical volumes belonging
to volume groups version 1.0. Sparing is
not supported for physical volumes belonging
to volume groups version 2.0 or higher.
This option requires the installation of the
optional HP MirrorDisk/UX software.
This option allows you to change the physi‐
cal 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 phys‐
ical volume within this volume group becomes
unavailable (fails). sparepv can have one
of the following values:
Change the specified physical volume to be a
"stand-by" spare for its
volume group. The specified physical
volume must not have extents allo‐
cated on it (i.e., no logical volumes
residing on it) at the time this com‐
mand 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.
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 immedi‐
ately available for use by logical
volumes. If the physical volume is an
"active" spare, that is, it was pre‐
viously a stand-by spare but then
took over for a failed physical vol‐
ume, 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.
(See section). This option specifies LVM's
proactive polling behavior on alternate
links. proactivepolling can have one of the
following values:
Enable LVM's proactive polling for alternate
links of a physical volume.
LVM will periodically test alternate
links. This is the default.
Disable LVM's proactive polling for alter‐
nate links of a physical volume.
LVM will not periodically test alter‐
nate links.
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 adminis‐
trator to ensure that the data on the disk is sufficiently mirrored to
satisfy availability requirements prior to making the device unavail‐
able by detaching it.
Although detaching a path or physical volume ensures it is unavailable
to LVM, attaching a path or physical volume will not necessarily make
the path or physical volume available again. Attaching a path or phys‐
ical volume 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 physical volume 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 command (see vgchange(1M)). If the objective is to
permanently add or remove a path or physical volume from the volume
group, the or commands (see vgextend(1M), and vgreduce(1M)) should
instead be used.
Warning: Detaching any physical volume or path using the or options
also disables automatically attaching any paths to any of the physical
volumes in the volume group. LVM will no longer attempt to automati‐
cally recover any unattached physical volumes in the volume group, not
just the ones explicitly detached. To cause LVM to once again automat‐
ically attach devices in the volume group use the options of command.
Attaching or Detaching Physical Volumes in Shared Volume Groups
The scope of the command is limited to the specific node on which it
runs. Systems that are part of a Serviceguard cluster operate indepen‐
dently. To replace disks that are part of a volume group shared by a
Serviceguard cluster, the physical volume must be detached and attached
independently on each of the systems in the cluster.
Alternate Links (PVLINKS)
In this release of HP-UX, LVM continues to support Alternate Links to a
device to allow continued access to the device, if the primary link
fails. This multiple link or multipath solution increases data avail‐
ability, but does not allow the multiple paths to be used simultane‐
ously.
There is a new feature introduced in the Mass Storage Subsystem on this
version of HP-UX that also supports multiple paths to a device and
allows access to the multiple paths simultaneously. The Mass Storage
Subsystem will balance the I/O load across the valid paths. This new
multi-path behavior is enabled and disabled through the use of the com‐
mand. See scsimgr(1M) for details.
It is no longer required or recommended to configure LVM with alternate
links. However, it is possible to maintain the traditional LVM behav‐
ior. To do so, both of the following criteria must be met:
· Only the legacy device special file naming convention is used
in the volume group configuration.
· The command is used to disable the Mass Storage Subsystem mul‐
tipath behavior.
EXTERNAL INFLUENCES
Environment Variables
determines the language in which messages are displayed.
If is not specified or is null, it defaults to (see lang(5)).
If any internationalization variable contains an invalid setting, all
internationalization variables default to (see environ(5)).
EXAMPLES
Prohibit the allocation of additional physical extents to a physical
volume:
Allow the allocation of additional physical extents to a physical vol‐
ume:
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 cur‐
rent path works:
Switch paths whenever a better path becomes available again after a
failure, even if the current path is fine:
Manually switch a physical volume to use another controller path:
Set the IO_timeout value for a physical volume to 60 seconds:
Set the IO_timeout value for a physical volume to zero (0) to use the
driver default:
Change the (empty) physical volume to become a stand-by spare for the
volume group:
Change the (active or stand-by) spare physical volume to become a regu‐
lar member of the volume group:
Enable LVM's proactive polling of alternate links
Disable LVM's proactive polling of alternate links
Detach a path to a physical volume
Detach all the paths to a physical volume
Attach a path to a physical volume
The command may be used to attach all the physical volumes in the vol‐
ume group and resume, automatically attaching the failed physical vol‐
umes.
WARNINGS
If the Mass Storage Subsystem multipath solution is enabled, the com‐
mand options that are link specific may not stop I/Os or switch links,
as they did in earlier releases. This means that and may not stop all
I/Os on a given path. The command should be used to disable the links.
When the proactive polling is enabled, LVM will not be testing alter‐
nate links unless legacy mode is in operation, even if legacy paths are
being used.
SEE ALSOpvdisplay(1M), scsimgr(1M), vgcfgbackup(1M), vgchange(1M). vgex‐
tend(1M), vgreduce(1M), environ(5), lang(5), intro(7), lvm(7).
pvchange(1M)