High-availability storage

[scottd at cloud9.net]

Greetings,

I'm looking for some information on high-availability direct-attached 
storage with FreeBSD.  To be specific, some form of RAID 6 with 12 to 16 
SATA drives (500 or 750GB).

We have a 2TB NetApp filer, but will soon be outgrowing it.  More NetApp 
space would be nice, but it's expensive and not as dense (144 or 300GB 
SCSI drives only) as other options.  Given that FreeBSD now has snapshot 
support, and dual parity disk setups are more common than a few years ago, 
it's an attractive option.

What's frustrating is that none of the external SATA controllers supported 
by FreeBSD (Areca 1120ML, Adaptec 4805) have more than 128MB of cache. 
Using SATA to Fibre Channel would be the next choice, with RAID 6 being 
handled by the array itself (Nexsan SATABoy, for example) but FC support 
on FreeBSD seems limited.

Any thoughts?  Thanks.

  - Scott