How do you attach two suns to a single SSA?

[Doug Hughes]

>
>We have an ultra-2 attached to an SSA 200 series, utilizing only about
>1/2 of the disks in the array. We'd like to attach a second ultra to the
>array, such that:
>	* it could use the unused disks on an everyday basis
>	* in the event of a failure of the first ultra-2 the second system
>		could import the volumes from the failed system and use
>		them.
>I understand that we cannot access the same disks from two systems at the
>same time - this is not an issue.
>
>A sun sales engineer said that we'd have to add a second controller to the
>array, attach the second system to the second controller, attach half
>the disks to the second controller, and thus not be able to import the other
>disks. Do y'all agree with this?
>
>system1-----------------------|array1-controller1--disjoint_set1
>                              |
>system2-----------------------|array1-controller2--disjoint_set2
>
> I thought that we could install a second port on the existing array
>controller, connect the second system to it, and logically access disjoint 
>sets of disks in the array, but with the ability to import the other 
>system's volumes in the event of the failure of that system. 
>

That's the way it works on the SSA1XX series. You just add a second
FO card onto the existing controller and connect it to your second machine.
The disks must be in separate disksets on the storage array, but that
sounds like it work fine for you.

>system1ctrlr1----------------------|                  
>                                   |array1-controller1
>system2ctrlr2----------------------|                  
>                                                      
>
>I also had the impression that we could have the following config:
>
>system1-ctrlr1----------|
>system1-ctrlr2-------|  |
>		     |  |----------|array1-controller1\
>                     |             |                   \
>                  |--|-------------|                    \ bunch of disks
>                  |  |                                  / in one array
>system2-ctrlr1----|--|--|                              /
>system2-ctrlr2----|  |  |----------|array1-controller2/
>                     |             |
>                     |-------------|
>

Don't know about this. You can do this with 2 storage arrays for sure, not
sure how the 200 works exactly (multiple controllers vs multiple optical
modules)

>(if we can't access disks in the array simultaneously from two systems
>thru a single controller) such that the second connection to each controller
>is just a hot-spare connection, to be used only in the event of a failure
>of one or the other system - true???
>