zfs - How can I monitor HP P410 hardware RAID degraded in Freenas

I would like to run freenas on a HP P410 hardware RAID 5
4x600GB 15k SAS array and be alerted in the case of physical disk failure, however the
freenas documentation
says:

to prevent
problems, do not enable the S.M.A.R.T. service if your
disks are controlled
by a RAID controller as it is the job of the
controller to monitor S.M.A.R.T.
and mark drives as Predictive Failure
when they
trip.

As the
machine is installed in a lights-out data center, there's no way for the controller to
alert anyone of RAID array being degraded. S.M.A.R.T. would appear to be an option -
perhaps a physical disk failure would show as a high "Reallocated Sectors Count" at the
array level?

Notes: Other options I
have considered, but rejected are: Using a dumb HP H220 HBA with RAID-Z (<1.2TB
guaranteed) or RAID 10 (1.2TB), but neither provide the capacity of RAID 5 (1.8TB), and
I don't have any spare drive bays (HP DL120 G7). Also, there doesn't appear to be an HP
agent for BSD.
Context: I have a pair of these servers to reconfigure (main
and replicated - 8 disks total) and they provide for an SQLServer and other VMs via
iSCSI.

Update: I'm going down the cciss route
( href="https://docs.google.com/document/d/1dvSPLpaJvOw96LFDDbB5y5H_o02jJSKlRLBuTAXVaiM/pub"
rel="nofollow noreferrer">here's how I installed cciss on FreeNAS 9.x).
Other possibility: RAID controller with out-of-band management on
ethernet.