VERITAS File System 4.1 Administrator's Guide

The VERITAS File System
Storage Checkpoints
Chapter 1 29
Storage Checkpoints
To increase availability, recoverability, and performance, the VERITAS File System offers
on-disk and online backup and restore capabilities that facilitate frequent and efficient
backup strategies. Backup and restore applications can leverage the VERITAS Storage
Checkpoint, a disk- and I/O-efficient copying technology for creating periodic frozen images of
a file system. Storage Checkpoints present a view of a file system at a point in time, and
subsequently identifies and maintains copies of the original file system blocks. Instead of
using a disk-based mirroring method, Storage Checkpoints save disk space and significantly
reduce I/O overhead by using the free space pool available to a file system.
See "Storage Checkpoints" on page 65 for information on using the Storage Checkpoint
feature. Storage Checkpoint functionality is a separately licensable feature.
Online Backup
VxFS provides online data backup using the snapshot feature. An image of a mounted file
system instantly becomes an exact read-only copy of the file system at a specific point in time.
The original file system is called the snapped file system, the copy is called the snapshot.
When changes are made to the snapped file system, the old data is copied to the snapshot.
When the snapshot is read, data that has not changed is read from the snapped file system,
changed data is read from the snapshot.
Backups require one of the following methods:
• Copying selected files from the snapshot file system (using find and cpio)
• Backing up the entire file system (using fscat)
• Initiating a full or incremental backup (using vxdump)
See “Online Backup Using File System Snapshots” on page 117 for information on doing
backups using the snapshot feature.