Veritas Volume Manager 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

Moving Disk Groups Between Systems
148 VERITAS Volume Manager Administrator’s Guide
For example, the following command creates the disk group, newdg, that includes the
specified disks, and has a base minor number of 30000:
# xvdg init newdg minor=30000 c1d0t0 c1t1d0
If a disk group already exists, you can use the vxdg reminor command to change its base
minor number:
# vxdg -g diskgroup reminor new_base_minor
For example, the following command changes the base minor number to 30000 for the
disk group, mydg:
# vxprint -g mydg reminor 30000
If a volume is open, its old device number remains in effect until the system is rebooted or
until the disk group is deported and re-imported. If you close the open volume, you can
run vxdg reminor again to allow the renumbering to take effect without rebooting or
re-importing.
An example of where it is necessary to change the base minor number is for a
cluster-shareable disk group. The volumes in a shared disk group must have the same
minor number on all the nodes. If there is a conflict between the minor numbers when a
node attempts to join the cluster, the join fails. You can use the reminor operation on the
nodes that are in the cluster to resolve the conflict. In a cluster where more than one node
is joined, use a base minor number which does not conflict on any node.
For further information on minor number reservation, see the vxdg(1M) manual page.
Compatibility of Disk Groups Between Platforms
For disk groups that support the Cross-platform Data Sharing (CDS) feature, the upper
limit on the minor number range is restricted on AIX, HP-UX, Linux (with a 2.6 or later
kernel) and Solaris to 65,535 to ensure portability between these operating systems.
On a Linux platform with a pre-2.6 kernel, the number of minor numbers per major
number is limited to 256 with a base of 0. This has the effect of limiting the number of
volumes and disks that can be supported system-wide to a smaller value than is allowed
on other operating system platforms. The number of disks that are supported by a pre-2.6
Linux kernel is typically limited to a few hundred. With the extended major numbering
scheme that was implemented in VxVM 4.0 on Linux, a maximum of 4079 volumes could
be configured, provided that a contiguous block of 15 extended major numbers was
available.
VxVM 4.1 runs on a 2.6 version Linux kernel, which increases the number of minor
devices that are configurable from 256 to 65,536 per major device number. This allows a
large number of volumes and disk devices to be configured on a system. The theoretical