Toshiba Magnia 560S - Manual (Page 32)

RAID Overview 14
Introduction to RAID
Disk Mirroring
With mirroring (used in RAID 1), data written to one disk drive is simultaneously
written to another disk drive. If one disk drive fails, the contents of the other disk drive
can be used to run the system and reconstruct the failed drive. The primary advantage of
disk mirroring is that it provides 100% data redundancy. Since the contents of the disk
drive are completely written to a second drive, it does not matter if one of the drives
fails. Both drives contain the same data at all times. Either drive can act as the
operational drive.
Disk mirroring provides 100% redundancy, but is expensive because each drive in the
system must be duplicated.