Online Backup Using File System Snapshots

This chapter describes the online backup facility provided with the VERITAS File System (VxFS). The snapshot feature of VxFS can be used to create a snapshot image of a mounted file system, which becomes a duplicate read-only copy of the mounted file system. This chapter also provides a description of how to create a snapshot file system and some examples of backing up all or part of a file system using the snapshot mechanism.

The following topics are covered in this chapter:

• Snapshot File Systems
• Using a Snapshot File System for Backup
• Creating a Snapshot File System
• Making a Backup
• Performance of Snapshot File SystemsDifferences Between Snapshots and Storage Checkpoints
• Snapshot File System Internals
• Snapshot File System Disk Structure
• How a Snapshot File System Works