Storage pools provide the storage administrator a lot of flexibility, including the ability to truly "pool" their storage, be able to tier between different drive types and performance characteristics, mix and match drives of different sizes, etc.

All of the above helps to simplify, where you can set your storage configuration and let it rock and roll. But before you start using Storage Pools as the end all be all, and completely replace the use of RAID Groups, there are several things you should be aware of.

First, under the covers of the pool there are certain "Private RAID Groups" being carved in certain multiples depending on the RAID type. This is very important to know, especially as you look to add more drives into the pool, to help maintain the valid number of performance, etc. I posted what these PRGs are in <a href="http://egroup.jasonmangone.com/emc-vnx-storage-pools-private-raid-groups">this post </a>

Second, there is a "guideline" I've found in several documents that states you should expand the pool by the same number of drives you've originally added into it. I've reached out to some internal contacts at EMC for clarification of the "why" on this, but haven't heard back just yet. In the meantime, I assume this is to maintain performance characteristics and possibly play better with some future capabilities (like rebalancing workloads across added drives).

Third, and one of the other VERY common Storage Pool questions we are asked/answer and deal with is if the pool can contain different RAID types per disk type. Meaning, if I have NL-SAS drives at 2TB each, I want to use RAID 6 for them, but if there are 600GB SAS Drives, I'd prefer RAID 5-- can I do that in the same pool?

Today, the answer is no, you can't. Futures are futures, so I can't say with certainty that you will this year (but you might be able to!).

So what does this mean? Well, we mostly see people creating Storage Pools with different drive tiers based on the desired RAID Group-- so a Storage Pool with EFDs and SAS drives would be RAID 5, and there would be a SEPARATE Storage Pool for the NL-SAS drives for RAID 6. This gives you the desired RAID groups for the disk types without causing you to lose additional disk space on the EFDs/SAS drives if you had them using RAID 6 also.

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