the data size is about 250 GB. Our system is of rather static nature,
definitely it is no classic OLTP. The typical wueries are reads by id with
joining 3 up to 6 big tables (each 50+ mln records).
However, I did performance comparison between our current setup
(DirectAttachedStorage, RAID5) and the new one (SAN via iSCSI through 1GB
LAN). The results were AFAIR 100% to 300% better, it was big improvement.