3.5.1 Matrix Server Administration Guide

Chapter 1: Introduction 8

Matrix Volume Manager

The Matrix Volume Manager can be used to create dynamic volumes

consisting of disk partitions that have been imported into the matrix.

Dynamic volumes can be configured to use either concatenation or

striping. A single PSFS filesystem can be placed on a dynamic volume.

The Matrix Volume Manager can also be used to extend a dynamic

volume and the filesystem located on that volume. Other Matrix Volume

Manager operations include recreating or destroying a volume.

PSFS Filesystems

PSFS filesystems can be created on either basic volumes or dynamic

volumes. A basic volume is a single disk, disk partition, or LUN imported

into the matrix. Dynamic volumes consist of one or more imported disks,

disk partitions, or LUNs and are created by the Matrix Volume Manager.

The PSFS filesystem provides the following features:

• Concurrent access by multiple servers. After a filesystem has been

created on a shared disk, all servers having physical access to the

device via the SAN can mount the filesystem. A PSFS filesystem must

be consistently mounted either read-only or read-write across the

matrix.

• Support for standard filesystem operations such as mkfs, mount, and

umount. These operations can be performed either with the

Management Console or from the command line.

• Support for existing applications. The PSFS filesystem uses standard

read/write semantics and does not require changes to applications.

• Quotas for users and groups, including both hard and soft limits.

• Journaling and live crash recovery. Filesystem metadata operations

are written to a journal before they are performed. If a server using the

filesystem should crash during an operation, the journal is replayed

and any journaled operations in progress at the time of the crash are

completed. Users on other servers will experience only a slight delay

in filesystem operations during the recovery.