HP Serviceguard A.11.20- Managing Serviceguard Twentieth Edition, August 2011

NOTE: You must use the vgcfgbackup and vgcfgrestore commands to back up and restore
the lock volume group configuration data regardless of how you create the lock volume group.
Setting Up a Lock LUN
LUN stands for Logical Unit Number. The term can refer to a single physical disk, but these days
is more often used in a SAN (Storage Area Network) or NAS (Network-Attached Storage) context
to denote a virtual entity derived from one or more physical disks.
Keep the following points in mind when choosing a device for a lock LUN:
• All the cluster nodes must be physically connected to the lock LUN.
• A lock LUN must be a block device.
• All existing data on the LUN will be destroyed when you configure it as a lock LUN.
This means that if you use an existing lock disk, the existing lock information will be lost, and
if you use a LUN that was previously used as a lock LUN for a Linux cluster, that lock information
will also be lost.
• A lock LUN cannot also be used in an LVM physical volume or VxVM or CVM disk group.
• A lock LUN cannot be shared by more than one cluster.
• A lock LUN cannot be used in a dual-lock configuration.
• You do not need to back up the lock LUN data, and in fact there is no way to do so.
A lock LUN needs only a small amount of storage, about 100 KB.
• If you are using a disk array, create the smallest LUN the array will allow, or, on an HP Integrity
server, you can partition a LUN; see “Creating a Disk Partition on an HP Integrity System”.
• If you are using individual disks, use either a small disk, or a portion of a disk. On an HP
Integrity server, you can partition a disk; see “Creating a Disk Partition on an HP Integrity
System”.
174 Building an HA Cluster Configuration