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Recommended raid config

We just installed two 1TB SATA shelves (28 spindles) that I want to configure in a single aggregate. These are the only 1TB shelves in the environment, so I need to dedicate two spindles (preferably one per shelf) as hot spares. I'm trying to figure out what raid config will give me the least amount of stranded drives yet maximize my usable space since the max aggregate size in DOT 7.3.2 is 16TB (19 data disks). Here's what I've come up with so far but I also need to take into account performance.

1) 5 RGs of 3D+2P = 25 used, 1 leftover. This gives me roughly 10TB usable space so I'm missing out on almost 6TB.

2) 4 RGs of 4D+2P = 24 used, 2 leftover. Only gets me one extra data disk.

3) 3 RGs of 5D+2P = 21 used, 5 leftover. But I could add another RG of 3D+2P. How does the third smaller RG effect performance? Essentially maximizes my usable space and strands 0 spindles. Thinking this is the best option assuming the mismatched RGs do not hinder performance.

4) 3 RGs of 6D+2P = 24 used, 2 leftover. essentially maximizes usable space.

5) 2 RGs of 9D+2P = 22 used, 4 leftover, essentially maximizes usable space.

Any recommendations? Am I on the right track here in my thinking that no matter what the RG size, if I can get 19 data disks I will be maximizing my usable space?

Thanks for the insight,

Jeff

Re: Recommended raid config

Jeff,

To my experience and knowledge I would never go with such a small RG configuration as they will be totally inefficient in terms of space and performance, with 1TB disk the layout I used previously and see people using it is Aggr1 (23 disks) = {[RG1 (9+2)]+[RG2 (10+2)]} which gives you total ~13.5 TB of usable space.

Would love to see how others use 1TB disk with the limitation of 16TB disk size.

Cheers,

Re: Recommended raid config

Hi Jeff,

IMHO you should use RaidGroupSize of 12. Two RaidGroups:

rg0 = 10 Data + 2 Parity

rg1 = 9 Data + Parity

The best practice says you shouldn't have a RaidGroup with less than 3 Data disks, I don't like small RGs.

See you,

Nascimento

NetApp - Enjoy it!

Re: Recommended raid config

Agreed. Go with the 12 and 11 raid groups with 7.3. One drive off is ok for performance and will only leave 3 drives behind to maximize usable.