3.5.1 Matrix Server Administration Guide

Chapter 5: Configure the SAN 65

As part of managing shared SAN devices, the SCL is also responsible for

providing each disk with a globally unique device name that all servers in

the matrix can use to access the device.

Device Names

The SCL uses unique device names to control access to shared SAN

devices. These names form the pathnames that servers use to access

shared data.

When you import a SAN disk, the SCL gives it a global device name that

represents the entire disk. The name consists of psd followed by an

integer. For example, psd1, psd2, and psd25 are all valid names.

Individual disk partitions also have a global device name. It consists of

the name assigned to the disk followed by p and the partition number.

For example, partition 6 on disk psd12 is represented as psd12p6.

Global device names are not dependent on the physical location of the

disks. If you move a disk that has already been assigned a global device

name, it will keep that name after the move.

If you import a disk that already has a device name, the SCL keeps that

name if it is not currently in use. If the name has been assigned to another

device, the SCL assigns a new name to the disk that you are importing.

Device Database and Membership Partitions

The SCL stores the device name and physical UID for each imported disk

in a device database. When you configured Matrix Server, you specified a

set of SAN partitions to be used for the database and for other functions

related to SAN control. These partitions are called membership partitions

and are automatically imported into the matrix. (For information about

creating these partitions, see “Manage Membership Partitions with

mxmpconf” on page 287.)

Matrix Server creates the device database on one of the membership

partitions and then replicates it to the other partitions. The database must

be present for a matrix to form. To ensure that the database is always

available, it is recommended that you create three membership partitions.