How to manually failover path to SAN-disk in Tru64 5.1-B?

[Terje Soreide]

Hi

Is it possible to manually failover a path to HSG80 LUN from Tru64? The reason why is that I want to balance the IO between both of the HSG80-controllers.

Regards
Terje Søreide

[Al Licause]

Might want to post this to a differnt forum since this is not really a network question.

[Al Licause]

Sorry.....I didn't realize I was in the system management forum when I posted the first reply.
Please ignore.

Al

[Greg Yates]

Hi Terje,

No intervention is necessary. Once the extra paths are needed, they are used. If you are watching each path, you may see that only one path is being used (with light IO). Crank up the IO and you should see it using more paths.

The beauty of Tru64 multipathing is that you don't have to do anything except have valid paths. :)

Greg

[Terje Soreide]

Greg

I agree that Tru64 is a beautiful OS, but the reason why I want to manually relocate the path is that I have a heavily loaded HSG80 controller, and therefore I want to balance the IO more evenly between the two of them. The only way I so far know this can be done is to set the lun preferred path to the other controller and restart the controller with the active path. The drawback with this method is that all other luns will failover to and there is no automatic failback mechanism in Tru64 or HSG80 as far as I know.

Regards
Terje

[Uwe Zessin]

It is possible with the SCU. You change the context to the desired path and send a "START UNIT" command.

# scu
scu> set nexus bus 5 target 2 lun 3
...
scu> start
scu> quit

[Terje Soreide]

I have tried the SCU command but have not been able to relocate a lun this way. Bus 0 and bus 4 is my HBA's.
The commands
scu>set nexus bus 4 target 0 bus lun 1
scu>start
should relocate lun 1 to the controller on bus 4 but I dont know which of the two paths seen from this controller the lun relocates to. So perhaps the lun in my case relocated to the same HSG80-controller.

Terje