I can certainly sympathize, as I have that problem occasionally with my iPod. But so far I haven’t seen that problem when running on my 8-core Mac Pro, also equipped with 16 GB of RAM.
In fact, the other day I was playing some music stored on the DroboPro, and at the same time ran several Xbench runs against the DroboPro, fully expecting the music to hiccup or the Xbench performance to be impacted, but nothing happened – neither task seemed to be impaired!
Now, I have 8 drives in my DroboPro, so it is quite possible that I was reading from one drive, and simultaneously writing to another drive, but even that would be rather impressive.
I suppose this could be caused by a disk read error that was silently corrected by the RAID mechanism. Unfortunately, Drobo doesn’t report such events (to my knowledge), except in the encrypted Diagnostic file.
if it happens again, I would suggest opening a Tech Support case and sending in the Diagnostic file. And we should continue to press DRI for more and better status summaries, so that a failing disk drive can be replaced before it is too late.