Optimising raid on 4k devices

[Matthew Moore <matthew@moore.sydney>]

Hi all,

I'm setting up a RAID6 array on 8 * 8TB drives, which are obviously 
using 4k sectors.  The high-level view is XFS-on-LUKS-on-mdraid6.

I've traditionally used partitions appropriately aligned to 4k sectors, 
however my understanding is that modern utilities properly recognise and 
align to the underlying disk structure.

Can I simply create the array on top of the physical disks, do I need to 
tell mdadm to offset/align, or do I need to continue to use partitions 
on the physical disks to get the best performance from this setup?

Many thanks in advance.