File server hardware config

Clarifications

You could do what we done and buy two identical servers, mirroring one to the other one or more times a day (we put ours in a different building, for more protection against disaster). It might also help you restore a 'just deleted' file quicker than from backup media.

I am looking at your configuration and wonder how this will help you in a disaster recover scenario.

Your configuration is great for availabilty and performance reasons.

You mention your DR goal. What exactly is the goal. I am assuming being able to rebuild your system in case it (or the location it is in) totally tanks.

Tony's reply, a totally mirrored system, preferably to a secondary location, is a DR solution, since you can bring it up if the primary system or site goes down. But with your specs you'd still have to define the Disaster Recovery steps for yur system.

As far as your server configuration goes, it looks ok. I used to setup servers w/ the same drive configuration. The more I thought about Raid5 though, the more I thought about how "safe" it is so I now just skip the mirroring, add 6 SCSI HD in a HW Raid5 configuration, with the 6th drive being a hot spare. Then I would partition the array into 2 separate partitions (1 for OS and 1 for Data.) With this configuration you would have to loose 2 drives before you were out of luck. Some probably don't like this configuration.
I know, Murphy's Law plays a part here, if you can loose 2 drives you will. I have heard of it happening.
This is where the DR could come into play. I agree with lowlands, your configuration has no DR about it. Tony's idea is something that I have implemented with several clients. If the building should blow up, or if their server dies a horrible death, we can have them up on another server fairly quickly with minimal data lose.

Good Luck!