IBM System storage DS6000 Series, Redbooks

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DS6000 Series: Concepts and Architecture
Figure 3-3 A host with a single path to the DS6800
For best reliability and performance, it is recommended that each attached host has two
connections, one to each controller as depicted in Figure 3-4. This allows it to maintain
connection to the DS6800 through both controller failure and HBA or HA (host adapter)
failure.
Figure 3-4 A host with two paths to the DS6800
SAN/FICON switches
Because a large number of hosts may be connected to the DS6800, each using multiple
paths, the eight host adapter ports that are available in the DS6800 may not be sufficient to
accommodate all the connections. The solution to this problem is the use of SAN switches or
directors to switch logical connections from multiple hosts. In a zSeries environment you will
need to select a SAN switch or director that also supports FICON.
Inter-controller data path
HBA
Single pathed host
Controller 0
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DA
Even LSS
Logical
Volumes Odd LSS
Logical
Volumes
Controller 1
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Inter-controller data path
Controller 0
HP HP HP HP
DA
Even LSS
Logical
Volumes Odd LSS
Logical
Volumes
Controller 1
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DA
HBA
Dual pathed host
HBA