High Availability FailOver/iX Manual (32650-90911)

Configuration
Planning
3. The storage array’s LUN must have the same LUN address for both the
primary path and alternate path. If a device is LUN 20 on the primary
path it must be LUN 20 on the alternate path. This also means that each
device LUN must be unique across both paths.
4. The total number of devices assigned to a primary and alternate path
pair should not exceed recommended maximums for the HBA you are
using. In the case of the NIO FW/SCSI card no more than 10 devices are
supported. With PCI-HVD SCSI connections up to 14 devices are supported.
Native Fibre Channel connections should generally not exceed 20 devices.
Configuring HAFO in Pairs
HP strongly recommends that ALL HAFO configurations evenly assign Ldev
primary paths to each member of HBA path pairs. That is if, you have four
Ldevs and two paths (“A” and “B”) then two Ldevs should have “A” as their
primary path (SYSGEN (io)) and two Ldevs should have “B” assigned as the
primary path. This is critical to avoid “silent” failures of an alternate path. It is
NOT recommended that all four Ldevs be assigned path “A” as the primary with
no other Ldevs assigned to “B”.
Figure 4-1 shows the Ldevs in the top path could be configured to failover to the
bottom path. If any of the Ldevs 1, 30, or 31 are configured to failover to the
bottom path, then all must be configured to failover to the bottom path. Further,
since in this example, some Ldevs indeed exist on the bottom path, they must all
(Ldevs 101, 102 and 103) be configured to failover to the top path.
Figure 4- 1 Configuring HAFO in Pairs
102
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High Availability Array
MPE/iX
Å Logical Physical Æ
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Ldev 1
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File
System
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Ldev 102
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Ldev 101
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Ldev 103
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