zfs discuss - May 2007 - RAIDZn+1 (related to the h/w raid ponderings)

Dropping in on this convo a little late, but here''s something that  
has been nagging me - gaining the ability to mirror two (or more)  
RAIDZ sets.

A little background on why I''d really like to see this....

I have two data centers on my campus and my FC-based SAN stretches  
between them. When I buy RAID arrays, I do so in pairs so that one  
array ends up in each data center, and the LUN config on these  
"matched" arrays are also the same. The server which consume those  
LUNs use software mirroring (via ZFS, SVM, or whatever) to mirror  
data in real time between the two arrays... in effect gaining me  
chassis-level redundancy in two separate buildings set half a mile  
apart. If one building goes up in smoke, I know that my data is fine  
in the other.

Anyway, lets now step down to the array level. These array disks are  
configured in RAID5 sets. This is a further level of redundancy so  
that if one of the arrays in a pair is out of service for an extended  
time, the remaining array can still withstand a drive failure.

Well, I''d like to get rid of that hardware RAID5 and use RAIDz... but  
then that would preclude my mirroring setup from happening since I  
can''t set up two distinct RAIDZn sets within a pool and mirror them.

For those familiar with ZFS internals, could a "RAIDZ+1"  
configuration be a distinct possibility?

/dale