HP-UX Reference (11i v2 03/08) - 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 checks the following criteria before it alters the VGID:
• All raw physical volume devices in the command line have the same disk type, such as:
1) EMC Symmetrix disks with the BCV attribute. (See EMC documentation.)
2) The XP disk array family with BC_SVOL or CA_SVOL attributes. (See XP256/XP512 related docu-
mentation.)
• All raw physical volume devices in the command line belong to the same VG. (See WARNINGS sec-
tion.)
Once the checks are successful, the same VGID is set on all the disks. It should be noted that for multi-
PV volume groups all the physical volumes should be split off and 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
Both the EMC and XP disk arrays have a feature which allows a user to split off a set of mirror copies of
physical volumes (termed BCVsorBCs) just as LVM splits off logical volumes with the
lvsplit com-
mand. 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 ori-
ginal devices. If
vgchgid is used on a subset of disk devices (e.g., two out of four disk devices), the two
groups of disk devices would not be able to be imported into the same VG 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 VG.
If a disk is newly added to an existing volume group and no subsequent LVM operations has been per-
formed to alter the structures (i.e., 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
writeable. 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.
HP-UX 11i Version 2: August 2003 − 1 − Hewlett-Packard Company Section 1M−−857