Datasheet

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 chdev –dev hdiskX –attr algorithm=round_robin, or
 chdev –dev hdiskX –attr algorithm=fail_over
These commands must be repeated for each hdisk.
6.3.2.3 Redundant VIOS LPARs with client-side MPIO (VSCSI)
Beginning with IBM i 6.1 with Licensed Internal Code (LIC) 6.1.1, the IBM i VSCSI client driver
supports MPIO through two or more VIOS partitions to a single set of LUNs (up to a maximum of
eight VIOS partitions). This multipath configuration allows a VIOS partition to fail or be brought
down for service without IBM i losing access to the disk volumes as the other VIOS partition(s)
remain active. Figure 9 illustrates the new capability for IBM i.
Figure 9: Redundant VIOS server concept.
Note that as with dual VIOS LPARs and IBM i mirroring, a VSCSI connection from IBM i to both
VIOS partitions is required. On the storage subsystem, it is recommended to create a host for
each VIOS containing the worldwide port names (WWPNs) of all FC adapters in that LPAR, and
then create a host group comprising those VIOS hosts. A single set of LUNs for IBM i can then
be created and mapped to the host group (shared access), giving both of the VIOS LPARs
access to the LUNs. Configuring redundant VIOS LPARs with client-side MPIO does not
preclude using MPIO within a VIOS for a higher level of resiliency, as described in the previous
section.
For storage systems such as DS8000 and XIV, these connections are typically shared through
the round-robin access as described earlier. So it is a good practice to have two or more
connections to each VIOS partition.