HP Serviceguard manual Types of Volume Manager, HP-UX Logical Volume Manager LVM

Types of Volume Manager

Serviceguard allows a choice of volume managers for data storage:

•HP-UX Logical Volume Manager (LVM) and (optionally) Mirrordisk/UX

•Veritas Volume Manager for HP-UX (VxVM)—Base and add-on Products

•Veritas Cluster Volume Manager for HP-UX

Separate sections in Chapters 5 and 6 explain how to configure cluster storage using all of these volume managers. The rest of the present section explains some of the differences among these available volume managers and offers suggestions about appropriate choices for your cluster environment.

NOTE: The HP-UX Logical Volume Manager is described in the HP-UX System Administrator’s Guide. Release Notes for Veritas Volume Manager contain a description of Veritas volume management products.

HP-UX Logical Volume Manager (LVM)

Logical Volume Manager (LVM) is the default storage management product on HP-UX. Included with the operating system, LVM is available on all cluster nodes. It supports the use of Mirrordisk/UX, which is an add-on product that allows disk mirroring with up to two mirrors (for a total of three copies of the data).

Currently, the HP-UX root disk can be configured as an LVM volume group. The Serviceguard cluster lock disk also is configured using a disk configured in an LVM volume group.

LVM continues to be supported on HP-UX single systems and on Serviceguard clusters.

Veritas Volume Manager (VxVM)

The Base Veritas Volume Manager for HP-UX (Base-VxVM) is provided at no additional cost with HP-UX 11i. This includes basic volume manager features, including a Java-based GUI, known as VEA. It is possible to configure cluster storage for Serviceguard with only Base-VXVM. However, only a limited set of features is available.

The add-on product, Veritas Volume Manager for HP-UX provides a full set of enhanced volume manager capabilities in addition to basic volume management. This includes features such as mirroring, dynamic multipathing for active/active storage devices, and hot relocation.

VxVM can be used in clusters that:

•are of any size, up to 16 nodes.

•require a fast cluster startup time.

•do not require shared storage group activation. (required with CFS)

•do not have all nodes cabled to all disks. (required with CFS)

•need to use software RAID mirroring or striped mirroring.

•have multiple heartbeat subnets configured.

Propagation of Disk Groups in VxVM

A VxVM disk group can be created on any node, whether the cluster is up or not. You must validate the disk group by trying to import it on each node.

Package Startup Time with VxVM

With VxVM, each disk group is imported by the package control script that uses the disk group. This means that cluster startup time is not affected, but individual package startup time might be increased because VxVM imports the disk group at the time the package starts up.

84 Understanding Serviceguard Software Components