Why Use UFS Snapshots?

The UFS snapshots feature enables you to keep the file system mounted and the system in multiuser mode during backups. Previously, you were advised to bring the system to single-user mode to keep the file system inactive when you used the ufsdump command to perform backups. You can also use additional Solaris backup commands, such as tar and cpio, to back up a UFS snapshot for more reliable backups.

The fssnap command gives administrators of nonenterprise-level systems the power of enterprise-level tools, such as Sun StorEdge^TM 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.