Veritas™ File System 5.0.1 Administrator's Guide

Warning: Some applications and utilities may not work on large files.

Access Control Lists

An Access Control List (ACL) stores a series of entries that identify specific users

or groups and their access privileges for a directory or file. A file may have its

own ACL or may share an ACL with other files. ACLs have the advantage of

specifying detailed access permissions for multiple users and groups. For VxFS

file systems created with the Version 5, 6, or 7 disk layouts, up to 1024 ACL entries

can be specified. ACLs are also supported on cluster file systems.

See the getacl(1) and setacl(1) manual pages.

Storage Checkpoints

To increase availability, recoverability, and performance, 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 a

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.

Storage Checkpoint functionality is separately licensed.

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 “About snapshot file systems” on page 75.

Introducing Veritas File System

Veritas File System features