This is a known issue with Brocade fabric @8gb/s.
FIllword should be set to 3 (if ARBF/ARBF fails, use IDLE/ARBF), if not you get bad_os error increasing continuously.
Beware, configuring the fillword will disable/enable the port, so do one port at a time with 5 min pause within each.
Regarding the eager thick zeroed, you should definitively look at the litterature about Thin on Thin, Thin on Thick, Thick on Thick and thick on thin
When dealing with a 3par, having hardware assisted thin provisionnig and global wide stripping, you should really consider using Thick on Thin (Eager Zeroed).
One Veeam value about using Thick VM disk is DirectSAN restore and CBT restore !! Think about it !