hard drives will always die. it's not a question of if, but when.
if you aren't using a RAID array, you probably don't need access to the data 24/7/356, which means you really should power off the disks when they're not in use. if you
are using RAID array, chances are with that many disks, you've already invested in a proper RAID controller. which means that even if one or two disks fail, you've already spent extra money (since you seem to have lots of it) on spare disks.
there are still plenty of good reasons to choose 1x1tb over 4x250. for one, you save a lot of physical space. for another, you end up only needing to power one drive, not four (which is still a problem in a desktop setup, since you need a massive PSU to power 15x or 24x drives). hdds to build up heat, so the fewer you have the less heat you have to deal with (not that it's safe to ignore, though). plus, with fewer drives and larger capacities, you can add more space to a standard setup without having to buy additional SATA ports.
still, at $450 per drive for 24x drives, plus maybe roughly $4000 for good server components including a proper RAID card, you're looking at a $16000 investment. though more expensive, you may want to invest instead in a sun X4500 [
http://www.sun.com/servers/x64/x4500/]. that beast features sun's new ZFS file system, for guaranteed data integrity regardless of how many disks fail (as long as it's not more than 2 at once, while it recovers data). of course, the X4500 isn't a toy, and requires a LOT of power, plus industrial-rated air conditioning systems and so forth. but a homegrown storage server would need something similar anyway...
Topic: Hitachi ships 1TB in a 3.5" drive (Read 4141 times)