|Total usable storage capacity (TB):||1.00|
|RAID type:||RAID 1 (mirror)|
|Number of RAID groups:||2|
|Number of drives per RAID group:||2|
|Total number of drives:||4|
|Drive capacity (GB):||500|
|Capacity of a single RAID group (GB):||500|
|Space efficiency:||0.5 (50%)|
|Fault tolerance:||1 disk drive per RAID group|
|IO penalty (read):||1/1 (one RAID IO per each host IO)|
|IO penalty (write):||2/1 (2 RAID IOs per each host IO)|
|Number of drives per RAID 1 group:||2|
|Single drive cost:|
|Cost per TB usable:|
RAID 1 is traditionally implemented with two drives. Each data block is written to both drives in the set.
RAID 1E or RAID 1 Enhanced utilizes 3 or more drives by striping data blocks across all of the drives in the set. In addition, data blocks are mirrored to another stripe within the set. Blocks in this stripe are rearranged to ensure that copies of each data block are stored on different drives in the set. RAID 1E supports odd and even numbers of drives per raid group.
RAID 10 (1+0) is a combination of RAID 1 with RAID 0 - data blocks are striped across multiple identical RAID 1 groups. RAID 10 requires minimum of 4 drives, and the number of drives must be even.
RAID 0+1 is a combination of RAID 0 with RAID 1 - data blocks are mirrored across two identical RAID 0 groups. From a capacity point of view, RAID 10 (1+0) and RAID 0+1 comprised of the same number of disks are identical.
3-Way Mirror (Triple Mirror) is implemented with three drives. Each data block is written to all drives in the set.