Different type harddisk speed on one scsi channel

[Clarence Lee]

Dear all,
On a hpux 11.0, could we house different type of harddisk speed on one scsi channel.
example like, one hardisk unit, with a speed of 15000 rpm and going addon another unit with 10000 rpm. Is this possible ?

Another question, is that can a harddisk with a speed of 15000 rpm mirror to a 10000 rpm of the same capacity ?
Your advise please.
Thanks, clarence

[njia_1 · Accepted solution]

Hi

Should not be a problem for mirroring, the only possible thing is the seek time of these two diskes.

If you create a mirror on the 10K rpm disk because the orginal disk is faster then it may take a little bit longer to sync but this is just theory. I donot believe this can be a problem.

It is also OK to connect these two diskes to the same SCSI channel as long as they are the same type, for example both Ultra3 or Ultra4.

thanks
Nan

[Alex Lavrov.]

No problem.

I have storage attached to L class with both 15KRPM and 10KRPM disks. HP technitian who replaced the bad disk, said that's not a problem.

Alex.

[Leif Halvarsson_2]

Hi,
Yes, it is possible but mixing devices of different performance on the same bus may limit the speed of the entire bus. If you have another 10K disk you should prefer using that and use the 15K disk in a place where you can utilize the performance of that device better.

[Mahesh Kumar Malik]

Hi clarence

You may mix hard disks of different speeds on same SCSI channels and also mirror the disks with different speeds, but it is not recommended to do so becuase of mismatch of IO bandwith performances.

Regards
Mahesh

[Steve Lewis]

Its not the spin speed that counts, but the type of SCSI interface. Make sure that they are both the same SCSI e.g. both Ultra-3, FW SCSI-2 or whatever. As has been said above, the bus controller itself will reduce the bus speed to whichever device has the lowest SCSI spec. Besides that, some specs are completely incompatible with others.

Apart from that I wouldn't want to mix spin speeds anyway due to general performance differences.

Yes you can mirror to a disk of a different speed but same capacity. BUT I would advise against putting them on the same bus.

[Clarence Lee]

Thanks for the answers and opinions provided.
Regards,
Clarence