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15.15 Save and Restore Scaling using a Virtual Tape Drive.
A 570 8 way System i was used for the following tests. A user ASP was created using up to 3 571F
IOAs with up to 36 U320 70 GB DASD on each IOA. The Chart shows the number of DASD in each test
and the Virtual tape drive was created using that DASD.
The workload data was restored into the system ASP and was then saved to the Virtual tape drive in the
user ASP. The system ASP consisted of 2 HSL loops, a mix of 571E and 571F IOAs and 312 - 70GB
U320 DASD units. These charts are very specific to this DASD but the scaling flow would be similar
with different IOAs the actual rates would vary. For more information on the IOAs and DASD see
Chapter 14 of this guide. Restoring the workloads from the Virtual tape drives started at 900 GB/HR
reading from 6 DASD and scaled up to 1.5 TB/HR on the 108 DASD. The bottle neck will be limited to
where you are writing and how many DASD are available to the write operation.
IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
© Copyright IBM Corp. 2008 Chapter 15. Save/Restore Performance 259
Large File Virtual Tape Scaling
(SAVE) Write to Virtual tape
0
100
200
300
400
500
600
700
800
6
D
AS
D
12
DA
S
D
18
DA
S
D
24
DA
S
D
30 DA
S
D
36 DASD
4
2
DA
S
D
4
8
DA
S
D
5
4
DA
S
D
60
DA
S
D
66
DA
S
D
72
DA
S
D
78 DAS
D
8
4
D
AS
D
9
0
D
AS
D
9
6
DA
S
D
1
02
DA
S
D
1
0
8
DA
S
D
GB/HR
RAID5 SAVE RAID6 SAVE MIRRORING SAVE
User Mix Virtual Tape Scaling
(SAVE) Write to Virtual Tape
0
50
100
150
200
250
300
6
DA
SD
12 DASD
1
8
DA
S
D
24 DASD
3
0
DA
S
D
3
6
DA
S
D
4
2 DASD
4
8
DA
SD
5
4 DASD
60 DASD
6
6
DA
S
D
72 DASD
7
8
DA
S
D
8
4 DASD
9
0 DASD
9
6
DA
SD
1
0
2
DA
S
D
1
08 DASD
GB/HR
RAID5 SAVE RAID6 SAVE MIRRORING SAVE