Western Digital Array Management Setup User Manual page 61

RAID 1
RAID 1 takes the data written on one disk and copies it to another, making a mirror or exact
copy. This arrangement does not have a significant performance advantage. If one disk fails,
there is no data loss. There is no rebuild, just a copy of the data to the disk.
Data Mirror
1 1
2 2
3 3
4 4
Disk Drives
WD ARRAY MANAGEMENT SETUP
USER MANUAL
APPENDIX A: RAID CONCEPTS - 57