Chapter 21. AIX 6.1 configuration guide 633
path to a paging device, the delayed_fail default setting is preferred, one such scenario
is AIX server direct attachment to the DS3500 controller host port.
To enable load balancing across multiple Fibre Channel adapters within the Virtual I/O
Servers when using the base AIX MPIO support, set the algorithm to round_robin for each
physical disk as shown in Example 21-8 and Example 21-9.
Example 21-8 Setting the round_robin parameter on VIOS
$ chdev -dev hdisk2 -attr algorithm=round_robin -perm
Example 21-9 Setting the round_robin parameter on AIX
# chdev -l hdisk2 -a algorithm=round_robin -P
Enable the health check mode for the disk so that the status of the disks is automatically
updated. Health check mode is disabled by default (hckeck_interval=0). As long as it is
disabled the client partition does not update the path status in case of a failure of the
active path. To activate the health check function, use the chdev command, as shown in
Example 21-10 and Example 21-11. In this example, we use a health check interval of 60
seconds. To check for the attribute setting, use the lsattr command.
Example 21-10 Changing the health interval parameter on VIOS
$ chdev -dev hdisk2 -attr hcheck_interval=60 -perm
Example 21-11 Changing the health interval parameter on AIX
# chdev -l hdisk2 -a hcheck_interval=60 -P
All these parameters can also be changed from Smitty mpio to MPIO Device Management
to Change/Show MPIO Devices Characteristics.
21.3 Setting up the DS3500 logical drives and host mapping
Map the logical drive(s) to the AIX operating system by using the normal procedure as
described in Chapter 11, “Administration - Mappings Tab” on page 275.
One of the important things to consider is using the correct Host type when mapping the
logical drive to the host from the IBM Storage Manager as shown in Figure 21-3 on page 634.
Note: It is necessary to set the reserve_policy to no_reserve (as shown in Example 21-4
and Example 21-5) before setting the algorithm to round_robin.
Note: MPIO for virtual SCSI devices currently only support failover mode in AIX.
Note: The path switching also works if the hcheck_interval attribute is disabled, but it
is recommended to have the status updated automatically.