Why Use UFS Snapshots?

The UFS snapshots feature provides additional availability and convenience for backing up a file system because the file system remains mounted and the system remains in multiuser mode during backups. Then, you can use the tar or cpio commands to back up a UFS snapshot to tape for more permanent storage. If you use the ufsdump command to perform backups, the system should be in single-user mode to keep the file system inactive when you perform backups.

The fssnap command gives administrators of non enterprise-level systems the power of enterprise-level tools, such as Sun StorEdge Instant Image, without the large storage demands.

The UFS snapshots feature is similar to the Instant Image product. Although UFS snapshots can make copies of large file systems, Instant Image is better suited for enterprise-level systems. UFS snapshots is better suited for smaller systems. Instant Image allocates space equal to the size of the entire file system that is being captured. However, the backing-store file that is created by UFS snapshots occupies only as much disk space as needed.

This table describes specific differences between UFS snapshots and Instant Image.