Mirroring system disks will protect the data when a physical disk on one side fails. However, data must be restored from backup data created in advance if the data is damaged due to a critical failure caused by multiple breakdowns and so on or by an operation mistake.
This section discusses the method of backing up the data of a system disk which is mirrored by GDS (GDS mirroring or ZFS mirroring) and a method of restoring from the tape in a ZFS boot environment.
