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SAN -- Realtime Recovery ?

I want 99+% uptime of our SAN.
What are some other possible solutions ?

Solution #1
  1. main SAN does "real-time" replication to Standby
     SAN at same hosting location over 1GB network
  2. Standby SAN does "hourly" replication to Standby
     SAN at another hosting location over 6MB network
Solution #2
  1. ....
3 Solutions
You have to decide between 2 bad cases:
a) Simple robust active/passive system
b) Complex active/active system

My personal experience is that (b) systems fails MORE OFTEN simply due to their complexity.
Worse than that, is the point that in most failure case, my customer had a real problem to find THE expert available to fix this cluster crap.

If you still want near real time availability, you should study if your main datacenter desserves a backup itself and go with (2) on a near real time transfer
I do  IBM SAN-SAN hardware replication. Basically replication (LUN copying) has two different varieties: the synchronous and asynchronous. Synchronous replication is cross reference to a RAID1, but over a larger distance. IBM got Metro Mirror (synchronous) and Global Mirror (asynchronous). The main challenge in SAN-SAN replication is to have enough bandwidth such as dark fiber for replication between the Data Centers.
Something like HP LeftHand multi-site bundle would do, two nodes on main site, two in DR centre. local replication is synchronous, remote replication asynchronous, does need enough bandwidth though as all changes are sent to the remote site - but you can cut that down by not having transaction logs or pagefiles on the SAN.
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