IBM System storage DS6000 Series, Redbooks

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DS6000 Series: Concepts and Architecture
Figure B-23 Multipath removes single points of failure
Unlike other systems, which may only support two paths (dual-path), OS/400 V5R3 supports
up to eight paths to the same logical volumes. As a minimum, you should use two, although
some small performance benefits may be experienced with more. However, since OS/400
multipath spreads I/O across all available paths in a
round-robin
manner, there is no load
balancing
, only load
sharing
.
Configuring multipath
iSeries has two I/O adapters that support DS6000:
򐂰 2766 2 Gigabit Fibre Channel Disk Controller PCI
򐂰
2787 2 Gigabit Fibre Channel Disk Controller PCI-X
Both can be used for multipath and there is no requirement for all paths to use the same type
of adapter. Both adapters can address up to 32 logical volumes. This does not change with
multipath support. When deciding how many I/O adapters to use, your first priority should be
to consider performance throughput of the IOA since this limit may be reached before the
maximum number of logical units. See “Sizing guidelines” on page 353 for more information
on sizing and performance guidelines.