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,
I would like to know the Flare on the existing array.
The EMC MirrorView development team verified that when using MV/S on LUNs that have Fast Cache enabled, high response times can result in canceled I/Os and mirrors that could subsequently fracture. When Fast Cache is disabled on the secondary array, response times return to normal.
This discussion can be helpful :