Mixing and matching SCSI Ultra320 drives

[Jonathan Klug]

Hi - can anyone plese tell me if it is possible to insert a 300Gb Ultra320 SCSI Hotpluggable drive into a server to replace a 146Gb or a 36Gb drive in a RAID 1 or RAID 5 array if that drive becomes faulty. We have a mix of servers which have 36Gb, 146Gb and 300Gb drives - all Ultra320 SCSI Hotpluggable and im trying to minimise the amount of spares I have to have.

On a similar issue is there an issueif we insert say a 15K RPM drive to replace a 10K RPM drive

Id really appreciate a response

Thanks

Jonathan

[JLester_1]

You should always keep the drives in an array the exact same size and speed. I am pretty sure the SmartArray controllers will not let you substitute a different size, not sure about speed though. Even if they would, it is not a good idea at all.

Like you, we have lots of different sizes and speeds. We just keep lots of spares.

[Jonathan Klug]

Hi Jason - thanks for the response. You are correct that it is best to replace faulty drives with the same drives. I did in fact eventuially get a response from HP who said that it is fine as long as the new drive is at least as fast and big as the drive you are replacing. I.e. if you insert a 146Gb 15K RPM drive to replace a faulty 36Gb 10KRPM drive then the new drive will function as a 36Gb 10K RPM drive.

It just gives you more flexibility in case you run out of spares.

Thanks again

JOnathan

[Uwe Zessin]

Most if not all of today's arrays do not implement 'spindle sync', so a 15kRPM disk drive will still rotate with 15kRPM when it is mirrored with a 10kRPM disk drive.

You can even use this 'hack' to upgrade capacity:
- remove one disk
- replace it with a larger one, wait for rebuild
- remove second disk
- replace it with a larger one and wait for rebuild

Check with ACU and you will see that there is now free space at the end of the disk drive array. You can put another logical disk in that space or grow the existing one.

A data disk's partition + filesystem can easily grown with Window's DISKPART.
We have done this a few times with 3 or 4-member RAID-5 sets.

Warning! It is not that easy to expand the C: partition and file system of a Windows server.