Dual storage IOA access optimization
View the active or passive path of your disk units and controller.
Dual storage IOA access characteristics can balance the controller workload. The dual storage IOA access characteristics for a disk array, parity set, specifies which controller is preferred to be optimized for the disk array. It performs direct read and write operations to the physical devices. The controller that is preferred to be optimized for the disk array, contains the active path to the disk units in the disk array. The other controller contains the passive path. The system only sends read and write operations down the active path. The passive path is only used if the active path fails.
Best performance is achieved when the dual storage IOA access characteristics on each disk array have a balanced workload. This happens when the two controllers have an equal number of disk arrays with active paths to the disk units.
The system selects the disk units and dual storage IOA access characteristics for each disk array. When creating disk arrays, set the parity set optimization to Performance. This attribute sets an even number of disk arrays (for example, 2, 4, 6, and so forth) to be created. It also enables the system to optimize disk arrays on each controller. As a result, the two controllers will have an equal number of disk units with an active path.
To change the parity set optimization, see Changing parity set optimization.
Viewing the active or passive path of disk units
To view the active or passive path of the disk units, complete the following steps.
- Select Work with disk units on the Use System Service Tools (SST) menu.
- Select Display disk configuration from the Work with Disk Configuration display.
- Select Display path status on the Display Disk Configuration display.
Display Disk Path Status
Serial Resource Path
ASP Unit Number Type Model Name Status
* * Y6800024F78E 433C 099 DMP001 Active
DMP002 Passive
* * Y680002AEB3D 433C 099 DMP003 Active
DMP004 Passive
* * Y6800024F754 433C 099 DMP005 Active
DMP006 Passive
* * Y6800024F771 433C 099 DMP007 Active
DMP008 Passive
* * Y68000268517 433C 099 DMP009 Active
DMP010 Passive
* * Y680002B31DD 433C 099 DMP011 Active
DMP012 Passive
* * Y6800024F74D 433C 099 DMP013 Active
DMP014 Passive
More...
Press Enter to continue.
F3=Exit F5=Refresh F9=Display disk unit details
F11=Display encryption status F12=Cancel Viewing the active or passive path role for a controller
To view the active or passive path role for a controller, complete the following steps.
- Select Start a service tool on the Use System Service Tools (SST) menu.
- Select Hardware service manager on the Start a Service Tool menu.
- Select Logical hardware resources (buses, IOPs, controllers) on the Hardware Service Manager menu.
- Select System bus resources on the Logical Hardware Resources on the System Bus menu.
- Select the Virtual IOP by typing a 9 (Resources associated with IOP) in front of the desired IBM® dual storage IOA.
- Press F11 (function key) until Path Role is shown.
Logical Hardware Resources Associated with IOP
Type options, press Enter.
2=Change detail 4=Remove 5=Display detail 6=I/O debug
7=Verify 8=Associated packaging resource(s)
Resource
Opt Description Type-Model Path Role Name
Virtual IOP * 572F-001 CMB01
Storage IOA 572F-001 DC02
Disk Unit 433B-099 Active DMP002
Disk Unit 433B-099 Passive DMP004
Disk Unit 433B-099 Active DMP006
Disk Unit 433B-099 Passive DMP008
Disk Unit 433B-099 Active DMP010
Disk Unit 433C-099 Active DMP012
Disk Unit 433C-099 Active DMP014
Disk Unit 433C-099 Passive DMP016
Disk Unit 433B-099 Passive DMP018
More...
F3=Exit F5=Refresh F6=Print F8=Include non-reporting resources
F9=Failed resources F10=Non-reporting resources
F11=Display status/resource name F12=Cancel 
