Booting from a large RAID

[Dominic Bishop]

I am looking to deploy some new fileservers shortly running on either
RELENG_6_2 or RELENG_6, these servers will have 16x500GB SATA drives running
on a 3ware 9650 raid controller.

Ideally I would like this to be configured as a single large RAID5 or RAID6
array, however this leaves me problems with installing the OS. I can't use
bsdlabel on a drive of this size as it has a 2TB limit, and as I understand
it I can't use GPT and put the OS on there since the bootloader code isn't
capable of booting from a GPT partition.

At this point I'm assuming my only option is a separate small HD for the OS
which can be partitioned using bsdlabel. Ideally I would rather not do this
however as the server cases only have 16 drive bays so I'll have to
sacrifice some capacity from the RAID in order to achieve this.

Just want to make sure I am correctly understanding the limitations around
what I want to do. Any comments/corrections to my line of thinking are
welcome.

Regards,

Dominic Bishop