Thank you as well as I am having a similar issue. Currently running ESXi 5.5 HP version on a HP ML10 v2.
My 8 HDD is already in an RAID array controlled by a LSI 9265.
1. I have tried to Putty into ESXi, but for some reason I can't have the right access privilege to change or create any files. So I can't get the vmkfstools to work.
(This is a non-Xpenology issue - I am just not a good Linux person)
2. When I pass through to a Windows VM on the same machine, the array is visible in Windows VM environment.
Best regards,
Jack