Intel 7xx Servers, 170 Servers, AS/400 RISC Server manual Nwsd Read Scaling

14.6.2.3 Virtual SCSI Bandwidth-Network Storage Description (NWSD) Scaling

Figure 3 shows a comparison of measured bandwidth while scaling network storage descriptions with varying block sizes of operations. Each of the network storage descriptions have a single network storage space attached to them. The difference in the scaling of these tests is attributable to the performance gain which can be achieved by adding multiple network storage descriptions. This experiment shows that in order to achieve better write performance from the hard disk, multiple network storage descriptions can be used. In order to achieve better performance, 1 network storage space should be used for every 2-4 disk drives in the ASP and each network storage space should be attached to its own network storage description.

NWSD Read Scaling

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Smal l T r ansacti ons	M edi um T r ansacti ons	Lar ge T r ansacti ons
(4k-16k)	(32k-64k)	(128k+)

A IX Nati ve

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		NWSD Write Scaling
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Small T r an sact oni	s	M edium T r an sact ion s	Lar ge T r an sact oni s
( 4 k- 16 k)		( 3 2 k- 6 4 k)	( 12 8 k+)

AIX Nati ve

1 NWSD Read

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8 NWSD Read

Figure 3 The figures above show performance while scaling network storage descriptions. This experiment shows that adding NWSD increases the throughput for write performance, which was not achievable using 1 network storage description. Read performance increases similar to the network storage space scaling figure.

IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
© Copyright IBM Corp. 2008	Chapter 14 DASD Performance	236