Effect and recommendationts of MirrorView on Fast Cache and VP

Hello everybody,

I have a question about best practices around VNX with Fast-VP and Fast-Cache and also using MirrorView/S to replicate to another VNX.

Suppose a write-intensive production load carried on a VNX with Fast-Cache and FastVP.

These production LUNs are mirrored with MirrorView/S to another VNX.

Should the replica LUNs on the second VNX also use Fast-Cache and/or Fast-VP?

I know there's a paper at EMC that recommends not using Fast-Cache and Fast-VP for the replica LUNs.

At EMC World 2012 I understood the same from an EMC speaker. He said that the I/O writes from MirrorView/S are very badly suited for Fast-Cache or Fast-VP.

But now that I think about it, I don't get it anymore:

The reason to put in Fast on the production VNX is to be able to carry the production I/O (write intensive). But this I/O is synchronously mirrored to the second VNX, so it seems logical that this second VNX should alsoe have the same amount of cache to carry the (write) I/O's?

Thanks for your experiences and/or ideas about this,

Francis