Hardware - SCSI HDD mixing in RAID

Author

SCSI HDD mixing in RAID

plantwiz

2003-11-07, 2:34 pm

Looking for some information to explain either side of this issue:

Can a SCSI RAID consist of different brand/size/model type (if same mfg)?

Above is the basic question. I just want to clarify for a moment that I am already aware RAID's are supposed to contain exact matching HDD's. I also have created RAID's with one or two drives being different.

The RAID's made up from different gerenration drives seem to be working just fine, but what are the PRO's and CON's to this arrangement?

What if you have a perfectly designed RAID and all drives match. Three years later one drive in the RAID fails - You cannot match the drive to the model. What do you do? Rebuild the RAID with newer drives? Install a similar drive, or the next generation model?

If you have links to specific data - I'd like to see it. Otherwise, your first-hand experience is fine.

Why am I asking? My experience says you can mix the drives, but two MFG's I spoke with this week say you cannot mix (of course they would prefer I buy their new drives).

Thanks

DaPunisher

2003-11-09, 1:18 pm

I have replaced 18.2G SCSI drives for a failed 9.1G. Tthe controller recognizes the 18.2 as a 9.1. Also, I have swapped a 15k rpm drive in a raid-5 with a 10k. the array slowed down to accomodate the slower drive.

azimuth40

2003-11-09, 2:50 pm

I agree with DaPunisher. Been there done the same things with the same results, got the T-Shirt.

plantwiz

2003-11-09, 4:00 pm

quote:
Originally posted by azimuth40
I agree with DaPunisher. Been there done the same things with the same results, got the T-Shirt.

Thanks guys,

I too have experienced the RAID working to the smallest and slowest drive.

I realize it isn't the ideal configuration, but really question why the MFG's keep saying that it won't work???

Point is, if in a jam and a RAID drive crashes/dies/etc... And it is a must fix situation, but the model of the drives in the RAID are scarce or no longer availalbe.... what is a person to do? I'd say, get the RAID up ASAP, continue to look for matching drive, but plan on upgrading all the drives in 6 month - 1 year (depending upon the budget).

Have either of you heard of anything within the drive architecture keeping a RAID from functioning?

A few generations ago, Maxtor had an 'upgrade' program to set up drives, but I don't see how nor why that even applies.

If you can match the drive pins to the cable on your controller card - it should be easy enough to select the RAID, and install the OS. The RAID and the drives will just match down to the slowest and smallest drive.

Do you recall anything special with Maxtor's drives? It has been so long ago (or seems to have been a long time ago) I don't recall - I'd recognize it when I saw it.

azimuth40

2003-11-12, 2:16 am

Well it depends on your definition of won't work. If you are a vendor guaranteeing a certain performance level on a spec sheet then it doesn't work, plain and simple. If you are a technician trying to get something back up then it works fine. When you are selling something, you have to be very careful.

enforcer

2003-11-12, 11:51 am

I think alot of it will be down to the manufacturer, we had a compaq sevrver, which would not accomodate different HD's even just the speed being different made them throw a wobbly.

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