Intel 170 Servers, AS/400 RISC Server Save/Restore Performance, Supported Backup Device Rates

Chapter 15. Save/Restore Performance

This chapter’s focus is on the IBM i operating system platform. For legacy system models, older device attachment cards, and the lower performing backup devices see the V5R3 performance capabilities reference.

Many factors influence the observable performance of save and restore operations. These factors include:

yThe backup device models, number of DASD units the data is spread across, processors, LPAR configurations, IOA used to attach the devices.

yWorkload type: Large Database File, User Mix, Source File, integrated file system (Domino, Network Storage, 1 Directory Many Objects, Many Directory Many Objects.

yThe use of data compression, data compaction, and Optimum Block Size (USEOPTBLK)

yDirectory structure can have a dramatic effect on save and restore operations.

15.1 Supported Backup Device Rates

As you look at backup devices and their performance rates, you need to understand the backup device hardware and the capabilities of that hardware. The different backup devices and IOAs have different capabilities for handling data for the best results in their target market. The following table contains backup devices and rates. Later in this document the rates are used to help determine possible performance. A study of some customer data showed that compaction on their database file data occurred at a ratio of approximately 2.8 to 1. The database files used for the performance workloads were created to simulate that result.

Table 15.1.1 backup device speed and compaction information

Backup Device	Rate (MB/S)	COMPACTION FACTOR
DVD-RAM	0.75 Write/2.8 Read	2.8 #1
SAS DVD-RAM	2.5	2.8 #1
SLR60	4.0	2.0
SLR100	5.0	2.0
VXA-2	6.0	2.0
6279 VXA-320	12.0	2.0
6258 4MM tape Drive	6.0	2.0
5755 ½ High Ultrium-2	18.0	2.8
3580 Ultrium 2	35.0	2.8
3592J Fiber Channel	40.0	2.8
3580 Ultrium 3 Fiber Channel)	80.0	2.0
5746 Half High Ultrium 4	120.0	2.0
3580 Ultrium 4 Fiber Channel	120.0	2.0
3592E Fiber Channel	100.0	2.5

#1. Software compression is used here because the hardware doesn’t support device compaction

Note the compaction factor is a number that used with the formulas in the following chapter to help describe the actual rates observed as the lab workloads were run using the above drives. This is not the compression ratio of the data being written to tape. I list them here to help understand what our experiments were able to achieve relative to the published drive speed.

IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
© Copyright IBM Corp. 2008	Chapter 15. Save/Restore Performance	243