You can now get a 20 TB SAN with high-end FC disks and integrated NAS appliance from the EMC for < 100 KEuros.

I think that if you use your database the same way you watch a movie (like reading sequentially some 10 GB files) throughput is the only point, and there will be no big deal between 8Gb FC and 10Gb ethernet.

If your database load is transactional, with many users performing short transactions (leading to 1KB synchroneous writes), latency will be the point.

As long as you hit the SAN's write cache (thus minimizing pure physical disk performance, and focusing on protocol and adapter overhead) you'll get at least 20,000 KIOps out of your FC SAN, which is out of reach by any 10Gb iSCSI).

If you reproduce a logfile activity with SQLIO (1KB unqueued, synchroneous, sequential writes to a 1 GB file, which will fit your SAN's write cache) you'll get, say 30 micro-second latency on 8Gb FC, vs. 200 micro-second on 10 Gb iSCSI (not even talking about NFS ;).

This latency is more or less the time taken by every _short_ transaction. Think about it if you cannot change an application that keeps over-committing onto your database.

http://www.demartek.com/Reports_Free/Demartek_LSI_CTS2600_Evaluation_2011-10.pdf