Any RAID Experts

[n5gooner]

Ok guys - I'm in a little battle with our special friends over the pond with RAIDs. I am an advocate of always using the same manufactures disk and same model number of disks in any RAID typically RAID1, RAID5, RAID10 or RAID50. Also this is the case with SANs. However my colleagues over the pond feel it is ok to mix disk manufactures and model numbers of disks, even sizes as long as they are all formatted to the same size. This is all for hardware driven RAIDs. I'd like some documenty evidence to present backing my point. I have a meeting this afternoon at 2pm..........anyone help????

Many thanks...............N5Gooner

[luke warm]

i am not a RAID expert...

For your meeting get them to explain the advantages in using different sized disks and different manufacturers disks. Is the reason just because these disks are already available or do they need to purchase the disks. If they need to purchase the disks then what advantage could there be to getting different sizes/manufacturers'

also - from http://www.storagereview.com/guide20...Selection.html

"To keep performance balanced and to maximize storage efficiency, drives should all be the same size and model."

"sometimes, drive failures are related to occasional manufacturing difficulties; this can cause a specific batch of drives to have a much higher rate of failure than normal for that drive family. If you set up six drives in a RAID 5 array and they are all from a faulty lot, you run the very real risk of having two simultaneous failures and losing the entire array. For this reason, you should get drives that are all the same make, model and size, but you should if at all possible get drives from different manufacturer lots."

[RSoles]

Have to say that my only experience with RAID was with SATA drives.
There I chose identical drives because of the SATA driver, not any RAID consideration (other than 'it seemed the logical thing to do).
RS

[DaveB]

I havn't messed with large disk arrays for a few years now but the general principle has always been to keeps your hardware environment as homogenous as possibe fo a number of reasons :

1: By mixing drive sizes you are wasting resources, All your disks will have to be formatted to the size of the smallest disk, making surplus space on larger drives unusable in the array.

2: Mixing drives degrades performance. The raid controller will have to throttle data flows to match the performance of the slowest drive. Even if the specs are nominally the same there will be measurable performance differances between manufacturers and models.

3: By mixing drives you are introducing additional risk factors into the array. In the event of problems it becomes much harder to isolate hardware issues if you are running a mixed environment.

4: KISS. Avoid unnessesary complications.