HP-UX Reference (11i v3 07/02) - 1M System Administration Commands N-Z (vol 4)

v
vgchgid(1M) vgchgid(1M)
NAME
vgchgid - modify the Volume Group ID (VGID) on a given set of physical devices
SYNOPSIS
/usr/sbin/vgchgid
PhysicalVolumePath [PhysicalVolumePath] ...
DESCRIPTION
The
vgchgid command is designed to change the LVM Volume Group ID (VGID) on a supplied set of
disks. vgchgid will work with any type of storage, but it is primarily targeted at disk arrays that are
able to create "snapshots" or "clones" of mirrored LUNs.
vgchgid accepts a set of raw physical devices
and ensures that they all belong to the same volume group, before altering the VGID (see WARNINGS sec-
tion).
The same VGID is set on all the disks and it should be noted that in cases of multi-PV volume groups, all
the physical volumes should be supplied in a single invocation of the
vgchgid command.
Options
vgchgid recognizes the following options and arguments:
PhysicalVolumePath The raw devices path name of a physical volume.
Background
Some storage subsystems have a feature which allows a user to split off a set of mirror copies of physical
storage (termed
BCVs, BCs, or Snapshots) just as LVM splits off logical volumes with the
lvsplit
command. As the result of the "split," the split-off devices will have the same VGID as the original disks.
vgchgid is needed to modify the VGID on the BCV devices. Once the VGID has been altered, the BCV
disks can be imported into a new volume group by using vgimport.
WARNINGS
Once the VGID has been changed, the original VGID is lost until a disk device is re-mirrored with the origi-
nal devices. If
vgchgid is used on a subset of disk devices (for example, two out of four disk devices), the
two groups of disk devices would not be able to be imported into the same volume group since they have
different VGIDs on them. The solution is to re-mirror all four of the disk devices and re-run
vgchgid on
all four BCV devices at the same time, and then use
vgimport to import them into the same new volume
group.
If a disk is newly added to an existing volume group and no subsequent LVM operations has been per-
formed to alter the structures (in other words, operations which perform an automated vgcfgbackup(1M));
then it is possible a subsequent
vgchgid will fail. It will report that the disk does not belong to the
volume group. This may be overcome by performing a structure changing operation on the volume group
(for example, using lvcreate).
It is the system administrator’s responsibility to make sure that the devices provided in the command line
are all Business Copy volumes of the existing standard physical volumes and are in the ready state and
writable. Mixing the standard and BC volumes in the same volume group can cause data corruption.
RETURN VALUE
vgchgid returns the following values:
0 VGID was modified with no error
1 VGID was not modified
EXAMPLES
An example showing how vgchgid might be used:
1. The system administrator uses the following commands to create the Business Continuity (BCV or BC)
copy:
1) For EMC Symmetrix disks, the commands are BCV establish and BCV split.
2) For XP disk array, the commands are paircreate and pairsplit.
Three BCV disks are created.
2. Change the VGID on the BCV disks.
vgchgid /dev/rdsk/c0t0d0 /dev/rdsk/c0t0d1 /dev/rdsk/c0t0d2
624 Hewlett-Packard Company − 1 − HP-UX 11i Version 3: February 2007