Bad idea to mirror boot root swap on shared scsi rail?

[Everett Bennett, Jr.]

Helo, me again,
I was in the midst of configuring a cluster on a pair of HP9000D370s. I am using a DeskSide Enclosure A3311A to support two sharred scsi rails. Rather than mirror boot, root, and swap all on the internal scsi0, I decided to put one 1/2 of each mirrored disk on the Deskside enclosure. Machine1 for example would have c0t5d0 as it's primary disk and c1t13d0 as the mirror. Machine2 again has c0t5d0 as primary, but c4t9d0 as it's mirror. Well now that I am 90% finished setting things up. I am getting cold feet wondering about the traffic on the shared busses (scsi1 and scsi4) as I also intend to put a Service Guard package that uses a disk that will be mirrored accross both shared busses (scsi1 and scsi4). Am I setting myself up for a flaky cluster and cruddy disk performance? Anyone care to comment?

Thanks

[Sanjay_6 · Accepted solution]

Hi Everett,

I don;t think you should have much of a problem. You should not worry about the traffic on the scsi bus. Though most of my system have the root disk on different buses than the sg disk. i don't think you should face any problem. You can observe the performance over a period of time and if you find there is some degradation in the i/o, you can always move the external mirror to the internal disk. you should be able to do so without bringing the system down, just reduce the mirror on the external disk and add the mirror on the internal disk. We have some other non sg systems where we have the roor mirrored on an external disk in an enclosure which has data disks too and we have not observed any performance problem.

Hope this helps.

Regds

[Everett Bennett, Jr.]

Thanks, that was just the kind of input I was looking for.