The performance considerations are marginal at best, on a very fast drive. I have done this for years and haven't noticed performance to suffer or improve either way. I don't benchmark, it's a waste of time when I know I've purchased high performance hardware to begin with.
Now, doing this on the same hard drive but separate partitions, that won't be as high performance as separate disks. But again, performance isn't the main reason why you would want to do this.
The primary reason is to separate your data from your operating system and programs. This is why many Unix systems have /home as a separate filesystem. OS upgrades don't interfere with your data. I've built my systems where "Program Files" was on a separate partition of the same disk the OS was on, and my data lived on a separate disk entirely. This made reinstalling the OS easy, but that practice is deprecated on newer Windows OS's. I don't install a lot of crap programs, so my OS doesn't get crufty, so I don't have to reinstall every 6 months to a year :-).
Nowadays with high speed gigabit ethernet and a basement available for noisy server systems, I keep my data on a separate physical system. Most of the data I'm accessing is media for playback on my HTPC, and gigabit is perfectly acceptable for streaming.
Any actual benchmarks to show the benefits of this strategy? – aaaidan – 2011-02-12T05:54:03.233
Would they fit into a normal PC tower? – Damien – 2009-07-20T13:31:49.460
I think 2 or 3 drives usually fit into a normal PC tower. But you can always check. ;) – KovBal – 2009-07-20T13:33:12.563
This varies depending on the system. Most towers only include two hard drive bays, but give more than enough 5 1/4" slots. You may need to get a mounting bracket. – Raymond Martineau – 2009-07-20T13:46:51.993
The only problem is apps that edit the registry will still need to be re-installed even if they were installed onto the 2nd drive. – ChrisF – 2009-07-20T14:11:57.427
He said he's going to install all applications to the system disk afaik. – KovBal – 2009-07-20T14:16:38.983
So he did - obviously skimmed over that on my first read through of the question. – ChrisF – 2009-07-20T14:19:50.663
I mean would a SSD fit it – Damien – 2009-07-20T14:22:56.027
So what does 2.5 compared to 3.5 mean? – Damien – 2009-07-21T16:29:10.360
(you can add it as a answer so I can upvote you) ;) – Damien – 2009-07-21T16:30:24.133