Option 1) 2 servers each having 2.0TB raid disk with SAS drives, 2GB ram and standard other features.
If going down this road, why not look into getting one of those fancy new storage enclosures where the RAID is built into the enclosure and can allow 2 servers to simultaneously access the arrays with full battery backed write-back cache?
What is available for Linux in this department?
I'm testing out an MD3000 from Dell. It can allow 4 hosts with single 4x serial paths, or 2 hosts with redundant 4x serial and can chain up to 2 MD1000s off it for up to 45 spindles.
It was 2 RAID controllers in 2 EMMs with 512MB BBU write-back that is synchronized between them which act as redundant RAID controllers. Ships with 4 plain-jane 2 path SAS controllers for host systems.
Downside, right now, it currently only supports SAS drives, they hope to have a SAS/SATA firmware update maybe by year-end.
Binary drivers from Dell?