become accustomed to larger and larger hard drives in consumer PCs, with the Terrabyte barrier broken some time ago, enterprise hard drives are still trailing behind. Part of the reason for this is that many high-speed enterprise drives use 2.5-in platters instead of 3.5-in platters, even though they're 3.5-inch drives.
The main reason for this is that 15,000RPM hard drives produce a lot of heat and as such need better cooling than the average desktop hard drive, and most of these drives have heatsinks built into the casing. More importantly, the drives need to allow for super fast data access, and as such, a smaller diameter of the disc means less head travel which speeds up data access.
Enough technology lessons already, the latest 15,000RPM hard drive from Hitachi - the Ultrastar 15K450 - packs no less than 450GB onto four platters. Add 16MB cache, an average latency of 2ms, and a seek time of 3.6ms and you've got a scorchingly fast drive.
Interface-wise, the Ultrastar 15K450 is available with either SAS connectivity or FibreChannel interface. This drive is guaranteed for 24/7 uptime and is meant to be used in mission critical systems.
You can find the product page here