When you say FAST do you mean FASTVP or FASTCache?

Considering its a 5100 where FASTVP is not supported I am curious about your questions

See http://support.emc.com/docu45748_FAST-VP-for-VNX-OE-for-Block-Release-Notes-Version-05.32.000.5.201.pdf P3 for the VNX's that are compatible

Also see emc267855

Which discusses the mutual exclusivity of enablers on VNX5100's

Hope that helps

Gearoid

Sorry to not clarify, FAST VP. I'm hearing now from others it is not supported but have an array that is in a state where all the tiers of storage were setup in a single pool. It appears some of them went to the slowest disk possible and was wondering if there is any easy way to correct this.

Hmm as I said its  not possible for data to tier on 5100 with FASTVP so I dont know how it could have got there with out seeing specifics

The only way that I can suggest is that you could correct it with a lun migration to luns that in specific tiers

Hope this helps

Gearoid

FAST VP is the relocation of slices between tiers in a pool based on their I/O temperature

That isn’t supported on the 5100

Of course the 5100 does support pools composed of different tiers – so there is an initial distribution – i.e. what slice get put onto which disk.

I think that is done based on capacity – i.e. we try to fill up the tiers equally.

Without FAST VP a block will stay on the disk that it was allocated initially.

With FAST VP in the latest releases you also get the new policy “Start High then Auto-tier” which means that new incoming blocks would be allocated on the fastest tier initially.

That only makes sense if you also use FAST VP to later move some of these that aren’t accessed frequently to a lower tier.

My advice – don’t create pools with different tiers on a 5100 if you cannot tolerate the performance of the slowest tier

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glen