Hi Steve,
I saw this thread and thought you may want to hear for one of the manufactures.
Medea offers a range of products of both Raid0 and Raid3 SCSI and Fibre solutions. The product you would be most interested in based on your need for protection is a product called the RTR320. This is a 5 dive SCSI Raid3 array built on an Ultra 320 controller. It has a sustained rate (from the front of the drive to the back of the drive) of 160 MB/Sec and burst rates over 200 MB/Sec. You get the capacity of 4 drives while one drive is dedicated data protection. With our array you can lose one drive and not lose your data or data rate which allows you to continue to edit. A lot of manufactures offer similar solutions but with a drive shutdown the performance comes to a crawl. Our array also offers MST (Multi Stream Technology) which is RAM caching system that aids in performance. A single 5 drive array is capable of 4 layers of 10 Bit SD or 4 layers of DVCPR0HD in real time.
As someone else mentioned there are other solutions out there that may be outside of the budget you specified. I would like the opportunity to speak with you directly and see if we can work something out. I can be reached at 888-296-3332 x109.
Mike Schuyler
Medea Corp