Hi
Have you been able to fix things together with Fujitsu?
If your virtual environment loses access to its storage, its basically one of the wort things that could happen.
That your host lost access to the datastore can have multiple reasons, cables, switch, storage controllers etc.
To avoid downtime due to a broken RAID, because of faulty controllers, double disk failure or whatever you need a mirrored SAN (DataCore, StoreVirtual, 3par remote copy, EMC VPLEX etc. etc.) so your hosts could have failed over the the second storage node.
Regards
Patrick