Have you set your users to use technologies like user profiles / directory synchronization, file replication etc.. and have recently moved to a EMC based NAS and virtually everyone is now taking forever to load / log on / log off / synchronize.  Conversely are you having issues using robocopy copying data to your NAS on subsequent copies (a lot of *Older* files that have not changed)

Here is what is going on:  EMC nas arrays (VNX File and Celerra) do not support NTFS time stamping, it in fact uses FAT time stamps (with a two second granularity) and not NTFS granularity which is down to +- 100 nano seconds.

Fix: if your problem is only robocopy and nothing else, you can add the /fft switch your list of switches used with robocopy (FFT is Fat File Times).

If your problem is more on the profile issue there is one setting you can change on the NAS: you can have the NAS round up the time stamp placed on the file as it rests on the NAS.  This will alleviate the *Older* files problem but it can cause a issues on the first updated sync as some of the files will be *Newer* and copied back down from the array to your client, but your client will now have the rounded time stamp on their file and all subsequent syn’s should not have an issue.

You can enable the setting of NanoRoundoff

$ server_param server_2 -f cifs -m nanoroundoff -v 1

You will have to restart CIFS on your NAS after setting the parameter to enable it.

For more information please see EMC Primus emc169068