Etch amd64 + perc6/E RAID arrays + clustering (heartbeat)

[admin at matphot.com]

Dear All,

First off, I've got four PE1950 machines running amd64 etch, each  
managing two MD1000's through perc6/E SATA controllers.

My goal is to develop an always-available, high-security (high  
performance if possible) data storage system.

Assuring the security/performance of the storage space under each  
server is not a great problem (either RAID 10 or RAID 50 or RAID 51),  
but I would like to consider perc6/E card failure, or the failure of a  
server itself, as I would like to provide a failproof-as-possible  
service that would be available uninterrupted around the clock. My  
idea was to have one server managing two first-level RAID 5 arrays  
'mirrored' (clustered) to another managing also two first-level RAID  
arrays, with the content of one RAID array on one server 'mirrored' to  
another under the other server.

I have read up on "heartbeat" (heartbeat-2) and it seems to do what I  
need as far as clustering servers goes, but what I can't find is a  
means to 'cluster' (or 'mirror') the contents of one RAID array to  
that of another under another server. Is this possible, or am I  
looking in the wrong place?

I am still rather new to this, so any and all advice would be a great  
help.

Thanks, best,

J.M.S.