DAS-208SA Disk Array User Guide
79
A. 8 Summary Table
Given: Net storage capacity = 8GB
:
RAID 1 = 2 ea. 8GB disks; RAID 2 = 11 ea.
1GB disks; RAID 3, 4 and 5 = 5 ea. 2GB disks. Disk seek and latency equal.
Spindle synchronized where needed. Numbers in parenthesis indicate how
many possible concurrent operations of that type are possible, if more than 1.
RAID
type
Read
transaction
rate*
Write
transaction
rate*
Transfer rate
per read*
Transfer rate
per write*
Parity/ ECC
Disk
overhead
Transaction
rate on
failure*
Transfer
rate on
failure*
1
2X = =
(2)
= 100%
= =
2
= = 8X 8X 27%
= 8X
3
= = 4X 4X 20%
= ‡
4
4X
=
= (4)
=
20%
= (<2)
<=
5 5X
≈
2X+
= (5)
= (2+)
20%
≈
3X+
‡
* Compared to a single 8GB disk.
‡ Varies with RAID manufacturer
