Yes network was our first suspect, but that was ruled out a couple of weeks ago. I was under the impression that windows defrag on a FAST VP LUN was not a good idea ?
Ill have to talk to the file adms, at the moment they are going to uncompress an entire volume and see whether that makes any difference on that particular server. Keeping it to one change at a time.
We have given them a new LUN for the decompression, disk space blow out from 300Gb to 500GB, which has been built on vmfs5 just in case that was an issue..
All LUNs are thick btw, eagerzeroed from the ESX side. In the case of the file servers they get one or more LUNs per guest so not shared with other guests.