The quoted numbers per GB are honest calculations, but they can be a little misleading because they don't reflect the REAL costs you are going to end up paying PER MONTH and UP FRONT. As with anything, you always have to run the calculations first.
An illustrative example: My co-founders and I recently looked at a bunch of new office spaces and were doing similar comparisons with costs per square foot for each space. We ended up in a situation where option A (a much larger space) looked MUCH cheeper at $17/sq.ft, but we ended up going with option B (a small space) at nearly $40/sq.ft. because we just didn't need all the space in option A, and option B was in an office facility where we wouldn't have to buy any additional furniture or appliances like couches, chairs, a coffee maker, fridge, etc. (they were supplied to all tenants in a large common area as part of the cost). So the REAL cost difference to us PER MONTH was about $400 LESS with option B (the smaller more "expensive" space) and came with a lot of extra conveniences to boot.
So in the example given in the article, if you're not using the full 45TB of backup storage space (24 x 2TB in RAID-6), you could actually end up paying significantly more per GB for what you have stored (what you're actually using) - ESPECIALLY when you include the UP FRONT costs of buying and co-locating the server and the maintenance costs that go along with it.
Moral of the story: Just because something LOOKS more expensive per unit doesn't mean it's actually GOING TO BE when it comes to cashflow. ALWAYS do the math for your own situation before making decisions like these.
Not sure how honest these calculations are because I couldn't repeat them and the article gives no REAL detail.
Cheapest matching configuration I could find at SoftLayer was $559 for a dual processor Xeon 5504 with 12GB RAM ("Speciality: Mass Storage"). Each 2TB drive costs an additional $60. I'm assuming the raid controllers come free if you can plug in that many drives so not adding that onto the build. Total for build with 24 drives: $1999. (Assuming a free OS, and that you don't need to upgrade the network port speed.)
24x2TB in RAID-6 gives you 45TB usable capacity (all 24 drives, madness) or 20TB usable capacity (12 drives in mirrored RAID-6 configuration, probably more sane).
45TB @ $1999/mo is ~$0.045/GB, but if more than 2 disks fail you're screwed (quite likely to happen in a 24 disk configuration!)
20TB @ $1999/mo is ~$0.1/GB, and you can stand to lose at most 4 disks (at most 2 in each of the mirrored array).
Compare with the $0.11/GB Amazon S3 is charging you to store data in the TB range (excluding data transfer costs, which are free for incoming data, which ought to be the bulk of data) and I'm not really sure I follow their argument given that maintaining this backup system is going to be a PITA and the risks don't seem worth it.
An illustrative example: My co-founders and I recently looked at a bunch of new office spaces and were doing similar comparisons with costs per square foot for each space. We ended up in a situation where option A (a much larger space) looked MUCH cheeper at $17/sq.ft, but we ended up going with option B (a small space) at nearly $40/sq.ft. because we just didn't need all the space in option A, and option B was in an office facility where we wouldn't have to buy any additional furniture or appliances like couches, chairs, a coffee maker, fridge, etc. (they were supplied to all tenants in a large common area as part of the cost). So the REAL cost difference to us PER MONTH was about $400 LESS with option B (the smaller more "expensive" space) and came with a lot of extra conveniences to boot.
So in the example given in the article, if you're not using the full 45TB of backup storage space (24 x 2TB in RAID-6), you could actually end up paying significantly more per GB for what you have stored (what you're actually using) - ESPECIALLY when you include the UP FRONT costs of buying and co-locating the server and the maintenance costs that go along with it.
Moral of the story: Just because something LOOKS more expensive per unit doesn't mean it's actually GOING TO BE when it comes to cashflow. ALWAYS do the math for your own situation before making decisions like these.