vgextend(1M) vgextend(1M)
NAME
vgextend - extend an LVM volume group by adding physical volumes
SYNOPSIS
autobackup] pvg_name] extensibility] sparepv] vg_name pv_path ...
DESCRIPTION
The command assigns additional physical volumes to volume group vg_name. The volume group must be active.
Volume groups are extended by adding one or more physical volumes specified by pv_path ...
For a volume groups version 2.0 or higher, adding a physical volume to a volume group may cause the maximum volume group size to be
exceeded (see vgcreate(1M)). If the maximum size has already been added to the volume group, then an attempt to add another physical vol-
ume will be rejected. If the maximum size has not been allocated, but the physical volume being added is larger than the remaining space
in the volume group, then the usable space on the physical volume will be limited to the remaining volume group space.
After the physical volumes have been successfully added to the volume group, the disk space they contain can be allocated to logical vol-
umes.
Before assigning an additional physical volume to a volume group, create the physical volume with the command (see pvcreate(1M)). Then,
create the volume group with the command, assigning at least one physical volume (see vgcreate(1M)).
If, for any reason, a specified physical volume cannot be installed into the volume group, an error message is displayed. However, the
installation continues to the end of the list of physical volumes.
When a pv_path refers to one of the physical volumes already in the volume group by a different pv_path name to indicate the use of a dif-
ferent controller, this new path becomes an to the physical volume. When two paths that reference the same disk are provided in the
pv_path list, the order of the paths is important. The first path becomes the "primary link" to the physical volume, the second becomes an
"alternate link" to the physical volume. The primary link is the path used to access the physical volume unless the primary link becomes
unavailable in which case LVM automatically switches to the alternate link to access the physical volume (see section). Currently LVM sup-
ports a maximum of 8 paths to a physical volume (7 alternates and one primary).
Options and Arguments
recognizes the following options and arguments:
pv_path The block device path name of a physical volume.
vg_name The path name of the volume group.
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 volume group.
This is the default.
After this command executes, the command (see vgcfgbackup(1M)) is executed for the volume group.
Do not back up configuration changes this time.
This option is only applicable for volume groups version 1.0.
Relocated blocks are not supported on volume groups version 2.0 or higher. Forcibly extend the volume group
with a physical volume which has alternate block(s) already allocated, (in other words, this physical volume was
not initialized using This option should be used with extreme caution. If the disk is being extended to a vol-
ume group with a different physical extent size, the alternate block(s) might be inside the user data area.
Potential data corruption could occur.
Extend an existing physical volume group
while the volume group is being extended by adding all the physical volumes in the pv_path parameter to the
physical volume group specified by pvg_name.
If the specified physical volume group does not exist, it is created, thus providing a means for creating new
physical volume groups after the volume group has been created. Another way to extend or add a physical volume
group is to edit the file as described in vgcreate(1M). See lvmpvg(4) for format details.
Set allocation permission for additional physical extents
on the physical volume specified by pv_path. extensibility can have one of the following values:
Allow allocation of additional physical extents on the physical volume.
Prohibit allocation of additional physical extents on the physical volume.
Logical volumes residing on the physical volume can still be accessed.
This option is only applicable on volume groups version 1.0.
Versions 2.0 or higher do not support sparing. This option requires the installation of the optional HP Mir-
rorDisk/UX software. It allows you to mark the physical volume(s) specified by pv_path to be either a spare
physical volume or a regular, non-spare physical volume. (A spare physical volume can 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.) sparepv can have one of the following values:
The physical volume(s) will be used as spare(s). No physical extents from
a spare physical volume will be available as part of the "free" pool of extents in the volume group. The
spare physical volume(s) will only be used in the event of another physical volume within this volume
group becomes unavailable (fails).
The physical volume(s) will be used as regular, non-spare members of the volume
group. This is the default.
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 availability, 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 scsimgr command. 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
behavior. To do so, both of the following criteria must be met:
o Only the legacy device special file naming convention is used in the volume group configuration.
o The scsimgr command is used to disable the Mass Storage Subsystem multipath behavior.
Shared Volume Group Considerations
For volume group version 1.0 and 2.0, cannot be used if the volume group is activated in shared mode. For volume groups version 2.1 (or
higher), can be performed when activated in either shared, exclusive, or standalone mode.
Note that the daemon must be running on all the nodes sharing a volume group activated in shared mode. See lvmpud(1M).
If the option is used, the file is changed only on the system where the command is issued (the server).
can add alternate PV links only on the server node; alternate links cannot be added on client nodes.
When a PV is added to the volume group, the PV path passed as the argument is added into on the server. However, on the clients, it is
always the PV persistent device special file that is added into is automatically updated on the nodes sharing the volume group.
When a node wants to share the volume group, the user must first execute a if physical volumes were added at the time the volume group was
not activated on that node.
LVM shared mode is currently only available in Serviceguard clusters.
EXTERNAL INFLUENCES
Environment Variables
determines the language in which messages are displayed.
If 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
Add physical volumes and to volume group
Extend physical volume group while adding physical volumes and to volume group
Add an alternate link to one of the physical volumes in the volume group where and refer to the same physical volume (referenced via dif-
ferent controllers), and the volume group already contains remains the primary link (in use) and becomes the alternate link.
Add a spare physical volume to a volume group:
WARNINGS
The new physical volume which has been added to the volume group could potentially have a different block size compared to physical volumes
already in the volume group.
If a logical volume is created on two or more physical volumes which have a different block size, it is not possible to use such logical
volume for file system purposes (see extendfs(1M)).
For example, when a logical volume contains physical volumes that all have 1k block size, and then it is extended to contain a physical
volume with 2k block size, then the block size of the volume group is increased to 2k.
SEE ALSO
pvchange(1M), pvcreate(1M), vgchange(1M), vgcreate(1M), vgdisplay(1M), lvmadm(1M), lvmpud(1M), intro(7), lvm(7).
vgextend(1M)