Your supposition that the luns are configured to different controllers is
correct.

The 2 different controllers do not speak to the same luns.

They are configured to each speak to mutually-exclusive luns.

HP-UX offers a capability known as controller failover. This feature is NOT
available with the HP3000.

The main benefit of using dual controller access to the HP3000 is for
load-balancing of I/O accross 2 controllers instead of the  maximum of 1
permitted by the Autoraid12H.

Automatic controller failover is NOT possible with MPE/iX.

And mod20 dual-controller access to the HP3000 has been available for as
long as I can recall - at least as far back as 5.5.


At 07:31 PM 2003-03-24, Atwood, Tim (DVM) wrote:
>I will jump in and say "no". At least not in the same sense as HP-UX. MPE
>does not recognize two different controllers pointing to the same set of
>LUN's. MPE does not know how to handle accessing the same data through two
>different paths.
>
>Prior to the release of 7.5, I had been told by several sources MPE 7.5 was
>going to be able to do this. However, so far as I have been able to tell
>this was not in 7.5 when it was released. It is possible I am missing
>something or it is still to come in 7.5 Express 1. If anyone has information
>on 7.5 and multiple controllers, I would love to hear it.
>
>I suppose one could configure one set of LUN's on one controller and another
>set of LUN's on the second controller. So if you have two interface cards
>you could configure the path of each card to each controller. Essentially
>creating two sets of drives. I have never tried this and I do not know how
>it would work with mirroring.
>
>But as far as I know any particular piece of data (disc address) would still
>only be accessed through one path and never the other path. For any one disc
>IO MPE can not do an "either/or" scenario between two controller cards. It
>would still only service the request through the controller for the LUN
>where the data resided.

Gilles Schipper

GSA Inc.
HP System Administration Specialists
300 John Street, Box 87651   Thornhill, ON Canada L3T 7R4
Voice: 905.889.3000     Fax: 905.889.3001
email:  [log in to unmask]  web: http://www.gsainc.com
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