3.1.2 Matrix Server Administration Guide

Chapter 1: Introduction 12

server, with a ratio of 8), paging can increase on the smallest server to the

extent that overall matrix performance is significantly reduced.

Multipath I/O

Multipath I/O can be used in a matrix configuration to eliminate single

points of failure. It supports the following:

• Up to four FibreChannel ports per server. If an FC port or its

connection to the fabric should fail, the server can use another FC port

to reach the fabric.

• Multiple FibreChannel switches. When the configuration includes

more than one FC switch, the matrix can survive the loss of a switch

without disconnecting servers from the SAN. Servers connected to the

failed switch can still access the fabric if they have another FC port

attached to another FC switch.

• Multiported SAN disks. Multiported disks can have connections to

each FC switch in the matrix. If a switch fails, disk access continues

uninterrupted if a path exists from a remaining switch.

When you start Matrix Server, it automatically configures all paths from

each server to the storage devices. On each server, it then uses the first

path it discovered for I/O with the SAN devices. If that path fails, Matrix

Server automatically fails over the I/O to another path.

The mxmpio command can be used to monitor or manipulate multipath

I/O (MPIO) devices. See “Matrix Server MPIO” on page 65 for details.

Supported Configurations

Matrix Server supports up to four FibreChannel ports per server, multiple

FC switches, and multiported SAN disks. The following diagrams show

some sample matrix configurations using these components. In the

diagrams, the FC fabric cloud can include additional FC switches that are

not managed by Matrix Server.