Managing Serviceguard Sixteenth Edition, March 2009

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”.
IMPORTANT: On HP 9000 systems, there is no means of partitioning a disk or
LUN, so you will need to dedicate an entire small disk or LUN for the lock LUN.
This means that in a mixed cluster containing both Integrity and HP-PA systems,
you must also use an entire disk or LUN; if you partition the device as described
below, the HP-PA nodes will not be able to see the partitions.
Creating a Disk Partition on an HP Integrity System
You can use the idisk utility to create a partition for a lock LUN in a cluster that will
contain only HP Integrity servers. Use the procedure that follows; see the idisk (1m)
Preparing Your Systems 203