IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

390 IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

11.2 DS6000 attachment to iSeries server

The DS6000 is supported on all iSeries models which support Fibre Channel attachment for

external storage. Fibre Channel is supported on iSeries models 270 and 8xx, and on all

~ i5 models.

Fibre Channel support was first provided in OS/400 V5R1. However, the DS6000 is not

supported on V5R1. The DS6000 is supported only on V5R2 and subsequent releases.

V5R2 was a major release for Fibre Channel support, providing:

򐂰 2 Gbps adapter speed

򐂰 Full switch in addition to point-to-point and arbitrated loop topologies

򐂰 Multi-target support

򐂰 Maximum of 32 LUNs per I/O adapter

Additional enhancements, including multipath support, were added in V5R3.

11.2.1 Fibre Channel adapters

There are two Fibre Channel device adapters used in iSeries servers for attachment of

external disk storage servers:

򐂰 2766: 2 Gigabit Fibre Channel Disk Controller PCI

򐂰 2787: 2 Gigabit Fibre Channel Disk Controller PCI-X

In iSeries terminology, a device adapter is referred to as an I/O adapter (IOA). Each adapter

requires its own dedicated I/O processor (IOP) within the iSeries server. The adapters are

auto-sensing and run either 1 Gbps or 2 Gbps. Each IOA can support up to 32 LUNs.

Table 11-1 shows a comparison of the performance of the 2766 and 2787 IOAs. These

numbers are in a controlled test and should not be expected in a typical client environment.

However, they do show the relative differences in the 2766 and 2787 IOAs. Specifically, the

2787 has 38 percent greater throughput than the 2766. Response time as measured by

iSeries Collection Services is 31 percent faster with the 2787 as compared to the 2766.

Table 11-1 Comparison of 2766 and 2787 I/O adapters

With multi-target support with OS/400 V5R2, multiple DS6000s can be supported from a

single Fibre Channel adapter initiator, but the total number of addressable LUNs remains 32.

This means, for example, that a single iSeries Fibre Channel disk adapter can have 16 LUNs

on each of two DS6000s.

11.2.2 DS6000 disk drives

The speed of the physical disk drive modules (DDMs) of the DS6000 disk megapacks can

have significant effect on performance. The throughput of a 15K rpm disk is generally about

33 percent greater than the throughput of a 10K rpm disk.

IOA Card Max Throughput

Over Single

Connection

(MB/s)

Response Time as

measured by

Collection Services

(Milliseconds)

Port Response Time

as measured

internally in DS6000

(Milliseconds)

2766 62 8.3 2.9

2787 86 5.7 1.3