Guys, here is a challenge for you...regarding hard disks

[IanB]

It seems you've got things rather about face there to me. I'm assuming that your F: drive is providing frequently accessed files to remote users (you mention downloads), so that is the drive that needs to have most availability and redundancy. It rather depends on the amount of data and the amount of money you have spare to throw at the problem, but a reasonable solution for the data you seem to have and the usage would be to use 2 disks as a RAID 1 mirror for your F: drive. This is at least as fast on reads as a single disk, provides good redundancy and may be as fast as a RAID 0 on reads with a good controller. However, if money is no object and you are providing a sharing service which must have very low downtime, upgrade to a good offboard controller card and go RAID6 (needs at least 4 disks) for more streaming speed with Enterprise-quality disks (Seagate ES or WD RE series) - 500GB ones are about the best bang-for-buck right now.

So you'll need at least one more 500GB drive to match your current one to make the mirror, or a new (faster? larger for expansion?) pair to make one from scratch. Remember you'll need at least one more 500GB+ drive to backup the data temporarily while you make the mirror, as you can't mirror an existing drive without losing all the data on it. Given the plummeting cost of 1TB drives, you're probably better off getting a pair of those, providing future expansion and backup space for other drives.

I'd then use the 2x 250GB drives as a second mirror to put only your games on. Same rationale: at least the same read speed as a single drive, maybe twice as fast, which is more important than the write speed. That's going to be the best way to reuse your smaller drives and makes sure they are set up redundantly if they are older to provide against failure. You also have a little expansion space there.

That then leaves the OS/apps drive. Short-stroking a larger drive gets you close to the same access times as a Raptor on this critical partition, and you then have lots of spare space for backups of the other drives. Redundancy won't hurt, even when the other drives are mirrored. I'd RAID 0 your 500GB drive with another identical one, so you are using the fastest first 10% of this set for your 50GB OS partition. Then add your user profiles partition (backed up on the F: RAID set) and use the rest as backup space.

So total extra cost would be 1 new 500GB to match your existing one and a matched pair of 750GB or 1TB drives depending on what you can afford. You'll need a mainboard with 6 RAID-capable SATA ports, or an offboard controller if you can afford it, but a newer ICH9R or ICH10R mainboard will be more than adequate for RAID 0 or RAID 1 with two disks in each set. 4 x 500GB Enterprise drives for RAID 6 would give you the same storage (at about the same cost) as 2 x 1TB drives in a mirror, but faster, so if you can afford the controller card go for it! You may not find RAID 6 available in anything less than an 8-port card, though, which would be very pricy.

EDIT: RAID 6 is safer than RAID 5 always, but for the same 4 disks RAID 10 (1+0) is an alternative with similar redundancy and identical price. I'm not sure of the relative risks of failure but I suspect the RAID 10 may be better and faster. No doubt stevecs can confirm that, if it isn't in the RAID sticky here. You'd also only need an extra 4-port controller if you don't have 8 RAID ports available on your mainboard, much cheaper...