I would suggest you to follow this:

https://mydocuments.emc.com/

You could refer to the document attached:

Yes, We are from EMC. And let us know if you need anymore info please.

Thank you for your input.

First of all, your best practices doc is outdated, I was referring to release 33 when starting the discussion. Second of all it does not have any info that would shed light on the question I asked.

I could find some more or less relevant info in the BP guide for release 33 on page 15, where it says the following:

"Use RAID 5 with a preferred count of 4+1 for the best performance versus capacity balance.

     Using 8+1 improves capacity utilization at the expense of slightly lower availability" - what about 8+1 performance?

I think EMC could have given us more info than that.

And lastly, Suman and Jiawen, do you work for EMC?

I would suggest you to go for 8+1 configuration. It will give better striping, in turn performance.

Thnx

Rakesh

Which document exactly you are referring to?

Refer this (with R33) http://www.emc.com/collateral/software/white-papers/h10938-vnx-best-practices-wp.pdf It gives you a self-explanation and Overview.

Thnx

Rakesh

Thank you, I have already read through it many times, it does not give a distinctive differences between 4+1 and 8+1, except this:

"Use RAID 5 with a preferred count of 4+1 for the best performance versus capacity balance.

     Using 8+1 improves capacity utilization at the expense of slightly lower availability"

And not a word about 8+1 performance under different workloads. I assume it is the same as 4+1, or even better, if you judge by the IOPs.

Striping on 5 drives and striping on 9 drives, doesn't look similar to me. Should be better. Moreover, we have MCx so shouldn't be worrying about hot-spares as long as there's 2 hot spare drives for a pool of 30 drives (EMC recommends min 1 with R33). (Of Course, we have to consider other factors as well, such as I/O size n numbers).

Thnx

Rakesh

Rakesh,

this is an apple to oranges comparison.

of course given the same raid level a raidgroup with more drive can provide more I/Os

you need to compare two setups with the same number of data drives.

There two 4+1R5 will provide better performance than one 8+1R5

For reasons please see Michaels explanation below