VERITAS Volume Manager 4.1 Administrator's Guide

Chapter 1 1

1 Understanding VERITAS

Volume Manager

The VERITAS Volume Manager (VxVM) is a storage management

subsystem that allows you to manage physical disks as logical devices

called volumes. A volume is a logical device that appears to data

management systems as a physical disk.

VxVM provides easy-to-use online disk storage management for

computing environments and Storage Area Network (SAN)

environments. Through support of Redundant Array of Independent

Disks (RAID), VxVM protects against disk and hardware failure.

Additionally, VxVM provides features that enable fault tolerance and

fast recovery from disk failure.

VxVM overcomes physical restrictions imposed by hardware disk devices

by providing a logical volume management layer. This allows volumes to

span multiple disks. VxVM provides the tools to improve performance

and ensure data availability and integrity. VxVM also dynamically

conﬁgures disk storage while the system is active.

The following sections of this chapter explain fundamental concepts of

VxVM:

• How VxVM Handles Storage Management

• Physical Objects—Physical Disks

• Virtual Objects

• Volume Layouts in VxVM

The following sections introduce you to advanced features of VxVM:

• Online Relayout

• Volume Resynchronization

• Dirty Region Logging (DRL)

• Volume Snapshots

• FastResync

• SmartSync Recovery Accelerator

• Hot-Relocation