Working with SPM groups
You can use Server Priority Manager to create SPM groups to manage multiple host bus adapters as a single group. All HBAs in an SPM group have the same priority. Prioritized WWNs and non-prioritized WWNs cannot be mixed in the same group. For the maximum number of WWNs you can register, see Cautions and restrictions for Server Priority Manager.
You can use an SPM group to switch priority of multiple HBAs from prioritized to non-prioritized, or vice versa. You can also use an SPM group to set the same upper limit value to all HBAs in the group. You can perform the upper-limit value control for the SPM group by setting the upper-limit value on the SPM group.
The upper-limit value of each HBA which belongs to the SPM group is the upper-limit value set for the SPM group divided by the number of HBAs which belong to the SPM group and have I/O. The I/O existence in HBA is distinguished with one minute interval monitoring. The upper-limit value of HBAs which belong to the SPM group is updated in one minute intervals. Therefore, when the existence of I/O is alternated, the upper-limit value of the SPM group might be over or under the setting value.
For example, in the condition that the upper-limit value is set to 200 IOPS for an SPM group to which 2 HBAs belong and only 1 HBA has I/O, the upper-limit value allocated to each HBA is 200 (200÷1) IOPS. After that, if the number of HBAs that have I/O turns from 1 to 2, until the next detection (updating the HBA upper-limit value which belongs to the SPM group is in one minute interval), the upper-limit value might become 400 (200+200) IOPS because the upper-limit value is allocated to 200 IOPS to each HBA, which is over the setting value for the SPM group.
In the condition that the upper-limit value is set to 200 IOPS for an SPM group to which 2 HBAs belong and 2 HBAs have I/O, the upper-limit value allocated to each HBA is 100 (200÷2) IOPS. After that, if the number of HBAs which have I/O turns from 2 to 1, until the next detection (updating HBA upper-limit value which belongs to the SPM group is in one minute interval), the upper-limit value might become 100 IOPS because the upper-limit value is allocated 100 IOPS to each HBA, which is under the setting value for the SPM group.