Pool or not to Pool?

Question

We just bought a VNX 5500. We bought it with lots of space up front. We initially purchased this to go behind an IBM Storage Volume Controller. After further research and a few recent issues with our CX4-240 and the IBM SVC we have decided not to put the VNX behind the IBM SVC. At this point we'll be doing all Block storage. We do not have any FAST licensing. The first thing we will be moving over are around 9.5TB of VMFS volumes on 4GB 15K FC drives and 5.5TB of SATA VMFS volumes worth about 275 VM server all together. Around 200 are production VMs the rest are test and dev. My first plan is to consolidate a bit and create 10 X 1TB VMFS volumes from our 19 X 500GB VMFS volumes. Our VMs are not I/O intense. The migration will be easy in the sense that we are just going to attach the new VMFS volumes to our ESX hosts and vMotion the servers over via Fiber Channel. That is some slight background. I guess my question is whether to make a dedicated pool for VMs or use standard RAID groups. I have 60 x 600GB 15k drives and I have 75 x 300GB 15k drives. Again I dont have any FAST software so will pools even gain me anything? Should I stick with say 10 different 4+1 RAID 5 arrays with the 300GB drives and create my 10 X 1TB VMFS from each array or should I create one big 50 disk pool and create 10 x 1TB VMFS out of that? Does it really matter performance wise and just consider ease of managment on the pool as opposed to the RAID groups? I plan on putting around 30-40 VMs on each 1TB VMFS. thanks for the info, Mark

dynamox · Answer

so currently you don't have any flash nor nl-sas drives ?

Rainer_EMC · Answer

There should not be that much of a performance difference between thick (fully provisioned) pool LUNs and similar LUNs built from traditional raidgroup with current VNX code

For thin LUNs there is a difference - but we are working on it

I don’t think there is a “one size fits all” answer whether to use pools or raidgroups.

I think we had most of the pro’s and con’s mentioned here – basically flexibility and ease of use vs. tighter control and placement

Markjc2 · Answer

Yes we do have 15 NL-SAS 1TB. I didn't add that as I didn't think having these would change anything since I do not have FAST software. Thanks, Mark

dynamox · Answer

i would consider pools, it's just so much easier to manage vs traditional raid groups/MetaLUNs. Plus you will put yourself in a position to take advantage of FAST at a later time.

Markjc2 · Answer

I ended up going with pools as it is closest to that of managing space behind SVC. You are correct on all the ease of use with pools and it would prepare me for FAST in the future.

Thanks for the suggestions!

Mark

VNX

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