I have to SVmotion all VM on my productions environment from shared storage to local storage on the host.
There are Windows server 2008 R2, 2012, microsoft exchange, linux, centOS, etc.
I wanted to know what are the risk of the SVMotion.
Shared storage : FreeNas 9.3 Stable
Host : Dell PowerEdge R710 and R610.
DS presented from the Freenas : VMFS5
DS on presented from host VMFS5.
That is, both source and destination are VMFS5 Datastore
There shouldn't be any issues with this. Only make sure that the host's RAID controller operates in write-back mode (the default with battery-backed write cache), otherwise you may experience very slow performance.
Go for it, but consider to do it during non-peak hours, and - just in case something goes wrong - after a full backup.
Storage vMotion is a "binary" transaction. It either succeeds, or it doesn't, in which case the VM will continue to run on the "old" storage.