Intel 7xx Servers, 170 Servers, AS/400 RISC Server manual 14.1.7.4

In comparing Mirroring and RAID one of the concerns is capacity differences and the hardware needed. We tried to create an environment where the capacity was the same in both environments. To do this we built the same size database on “15 35GB DASD using RAID5” and “14 70GB DASD using Mirroring spread across 2 IOAs”. The protection in the Mirrored environment is better but it also has the cost of an extra IOA in this low number DASD environment. For the 30 DASD and 60 DASD environments the number of IOAs needed is equal.

14.1.7.3

System Response Time (sec)

RAID-5 compared to Mirroring

571E/574F (15 - 35 GB DASD): IOPLess, RAID-5

571E (14 - 70 GB DASD): IOPLess, 7 Mirrored Pairs 2 IOAs 571E (30 DASD): IOPLess, 15 Mirrored Pairs 2 IOAs

571E/574F (30 DASD): IOPLess, RAID-5 2 IOAs 571E (60 DASD): IOPLess, 30 Mirrored Pairs 4 IOAs 571E/574F (60 DASD): IOPLess, RAID-5 4 IOAs

0.25
0.2
0.15
0.1
0.05
0
0	5000	10000	15000	20000	25000	30000	35000	40000
			Workload Throughput

		RAID-5 compared to Mirroring
14.1.7.4		571E/574F (15 - 35 GB DASD): IOPLess, RAID-5
		571E (14 - 70 GB DASD): IOPLess, 7 Mirrored Pairs 2 IOAs
(ms)		571E (30 DASD): IOPLess, 15 Mirrored Pairs 2 IOAs
		571E/574F (30 DASD): IOPLess, RAID-5 2 IOAs
		571E (60 DASD): IOPLess, 30 Mirrored Pairs 4 IOAs
Time	40	571E/574F (60 DASD): IOPLess, RAID-5 4 IOAs
Response	30
	20
	10
DASD
	0
	0	2000	4000	6000	8000	10000
				Ops/Sec
IBM i 6.1 Performance Capabilities Reference - January/April/October 2008

© Copyright IBM Corp. 2008 Chapter 14 DASD Performance 200