360 Systems 1200HD-EX - Manual (Page 102)

MAXX-1200 Owner’s Manual Page 101
About RAID 5
A RAID 5 configuration features the data striping of RAID 0, combined with the parity benefits
of RAID 4. Using a parity (exclusive OR) function, RAID 5 can tolerate the loss of one drive.
Parity information is distributed across all drives rather than being concentrated on a single
disk. This avoids throughput loss due to contention for the parity drive. Spare drives can be
used to rebuild an array after a drive is replaced.
RAID-5 capacity equals the size of drive times (number of drives -1). In addition, the array’s
storage efficiency increases with the number of disks; from 66.7 % for 3 drives to 75 % for four
drives: storage efficiency = (number of drives -1) X (number of drives).
P 10 11 12
RAID Level 5:
“Independent Access Array with Rotating Parity”
High Data Reliability & Transfer Capacity
Disk 2 Disk 1 Disk 0 Disk 3
4 5 P 6
1 2 3 P
7 P 9 8
Disk Array
Controller
DATA
Array Management Software
Provides Logical to Physical Mapping
Physical
Figure 38: RAID 5 Array Schematic
Improved Write Performance
The server uses new designs to improve RAID-5 write performance for both large sequential
and small random transactions. This advanced block caching firmware delivers extremely high
performance for RAID-5 write operations.