HP Serviceguard Storage Management Suite for VERITAS Veritas File System VxFS, VxFS Features

Veritas File System (VxFS)

Introduction

The Veritas File System (VxFS) is a high availability, high performance, commercial grade file system that provides features such as transaction based journaling, fast recovery, extent-based allocation, and online administrative operations, such as backup, resizing, and defragmentation of the file system. It provides high performance and easy manageability required by mission-critical applications, where high availability is critical. It increases the I/O performance and provides structural integrity.

The Veritas File System version (VxFS ) is the vxfs file system for HP-UX 11i v3 release.

VxFS Features

VxFS supports the following features:

•Extent-Based Allocation

An extent is defined as one or more adjacent blocks of data within the file system. VxFS allocates storage in groups of extents rather than a block at a time, thereby resulting in faster read-write operations.

•Extent Attributes

Extent attributes are the extent allocation policies associated with a file. VxFS allocates disk space to files in groups of one or more extents. VxFS enables applications to control extent allocation.

The setext and getext commands enable the administrator to set or view extent attributes associated with a file, as well as to preallocate space for a file.

•Fast File System Recovery

Most file systems rely on full structural verification by the fsck utility as the only means to recover from a system failure. For large disk configurations, this involves a time-consuming process of checking the entire structure, verifying that the file system is intact, and correcting any inconsistencies.

VxFS reduces system failure recovery time by tracking file system activity in the VxFS intent log. This feature records pending changes to the file system structure in a circular intent log.

•Access Control Lists (ACLs)

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.

•Online Administration

A VxFS file system can be defragmented and resized while it remains online and available to users. The online administrations operations supported are backup, resizing, and defragmentation.

•File Snapshot

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 and the copy is called the snapshot.

•Expanded Application Interface

VxFS supports the following specific features for commercial applications:

◦Pre-allocates space for files

◦Specifies fixed extent size for files

18 Introduction