Disk Mirroring - LSI MegaRAID Enterprise 1600 Hardware Manual

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.
8 MegaRAID Enterprise 1600 Hardware Guide