topic Re: Best Raid in Disk Enclosures

Best Raid

Sanjiv Bhatia — Tue, 30 Mar 2004 16:43:00 GMT

We have six drives, 4 are 18 GB and 2 are 36 GB. Can we do Raid 0 + 1? What would be the optimal Raid level with this hardware?

Re: Best Raid

Karthik S S — Tue, 30 Mar 2004 23:33:16 GMT

Are you using some kind of software RAID? I would suggest form one 4*18GB stripe, another 2*36GB stripe and finally mirror them.

-Karthik S S

Re: Best Raid

Eric van Dijken — Wed, 31 Mar 2004 00:28:50 GMT

It all depends....

For performance i would go for 1 RAID0 set of all the 6 drives. Best would be using 2 SCSI controllers.

But then again, there is too little information to give a good performance estimate.

What kind of system are you using?
What kind of bus speed are we talking about?
What kind of controllers are you using?
What kind of drives are they, cache, rpm, etc?

And please define "Optimal" and "Best RAID"

Re: Best Raid

Sanjiv Bhatia — Wed, 31 Mar 2004 07:50:37 GMT

Optimal is what we are looking for, this server will host Exchange 2003. DL380 w/5i Smart Array controller, the 18 GB drives are 10K the 36GB drives are 15K.

Re: Best Raid

Eric van Dijken — Wed, 31 Mar 2004 07:58:34 GMT

If performance is your destination (and not safety) RAID0 (with lots of Cache memory) is your best bet.

Head movement is still the nr. 1 time consumer in disk i/o. The more diskheads you use the faster the I/O (in general)

Be sure that you have a good backup (and restore) procedure. Not that is not safe to use RAID0, but one day one of the drives will fail and all the data will be gone.

Re: Best Raid

Sanjiv Bhatia — Wed, 31 Mar 2004 08:01:50 GMT

We definetly do want some type of redundancy, I guess we want something that will gives us the best mix.

Re: Best Raid

Eric van Dijken — Wed, 31 Mar 2004 08:15:44 GMT

My best estimate would be a 18,18,36 stripe, mirrored with another 18,18,36 stripe.
This way you don't have a fast and a slow diskset. But two of the same kind.

Search google for, SAME technology (Stripe All, Mirror Everything)

Re: Best Raid

Sanjiv Bhatia — Wed, 31 Mar 2004 08:31:44 GMT

Thanks for your help on this, I am unfamiliar with SAME hopefully I can find some good configuration docs.

Re: Best Raid

Jenny Urey — Thu, 01 Apr 2004 05:16:43 GMT

The better option would be RAID5 as you have redundancy however as you have 2x 36Gb and 4x 18Gb if RAID5 configured the 36Gbs would downsize to 18Gb.
So.... My suggestion would be to get your mitts on someting like an Adaptec 2100S, RAID5 the 4x18Gbs together. Then you could habe the 2x 36Gbs either to mirror or leave as a JBOD. Depends on the capacity you require!
Do you know exactly what data you are holding? Can this be archived? Does this data have to be live on your network....do you really need all this capacity??
May be worth you checking this out and sort your data now whilst capcities are fairly low!

Re: Best Raid

Jenny Urey — Thu, 01 Apr 2004 05:17:31 GMT