HP JFS 3.3 and HP OnLineJFS 3.3 VERITAS File System 3.3 System Administrator's Guide

30 Chapter1
The VxFS File System
Online Backup
Online Backup
The HP OnLineJFS product provides a method of online backup of data
using the snapshot feature. An image of a mounted file system instantly
becomes an exact read-only copy of the file system at a certain point in
time. The original file system is snapped while the copy is called the
snapshot .
When changes are made to the snapped file system, the old data is first
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
directly 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)
For detailed information about performing online backups, see Chapter
4 , “Online Backup.”