The storage unit is listed as offline, why?
Try to restart the services once and where is the disk storage created is that on ISCSI if ISCSI connection is terminating then disk storage can go offline so check for the events in event viewer
Also there is known issue with BE 2012 were disk storage goes offline during BE maintainence see if that matches too in your case
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Thanks, I will go to the client for testing. Surely the day Monday ...