The reason I ask is that the manual on pages 29-30 lists that IT/IR and IM/IME supporting "Hot-swap capability" while ESRT2 does not:
Yes ESRT2 does support hot swapping.
You attained "Hot-Swap Capability" if your hard disk drive is plug into drive cage/hard disk cage with backplane. If your hard disk is directly connected to the motherboard via SATA CABLE it doesn't have a hot-swap capability. ESRT2 is just a controller of the motherboard.
With regards the hard disk drive you've add and you got error, if your hard disk is configured in RAID you need to add/member that new hard disk to the existing RAID(if you are replacing a defective drive). If you add that as a different storage then you need to create another raid for that hard disk.
I hope this will help Sir.