|Not sure what you are looking for. Are you looking to setup RAID that would make ONE fault tolerant drive out of all of your SANs or are you looking to setup RAID on each SAN?|
Most RAIDs use Firmware that comes with the Backplain for RAID drives. There are Software RAIDs where the OS sets up the Fault Tolerance but most people including me, would suggest you steer clear of these because if the Software fails then you lose your data.
Ok, that being said. Most RAIDs use DAS drives because you need speed and a reliable connection between the drives to maintain the data replication and parity. So in theory you could do RAID but across a Network it is neither speedy nor reliable.
There are some systems being developed for MACs and Solaris like SoftRAID.
You could use Microsoft Windows Server 2003 Name Spaces to simulate a RAID drive. It is really replication which is Fault Tolerant. The problem with this is that it does not use Parity so it only simulates RAID 1 and you will only have as much space as your smallest SAN.
Not sure if I helped (Probably Not) but this is a very interesting subject and I would love to know what others come up with.