To anyone who was wondering the total storage in that rack (just HD's, not counting what is lost from raid) is 162TB. With colo'd and other machines my total storage is just under 200TB (quite a ways from 1PB).
Several of the machines in that rack keep backups of others and do not run 24/7. Only two of the machines run 24/7 (well five I guess if you count the two 30x3TB but those are JBOD chasis and aren't computers).
The power usage actually isn't very bad considering everything:
I am using the storage mainly for storing media. I just recently added the 90TB and until then my biggest system which contained almost all of my collection was 40TB but I was running out of disk space so I added 90TB. Since I did not just upgrade my current array (and move all my data to it) but instead added additional storage via JBOD chasis My biggest storage machine went from 40TB to 130TB. This storage should last me atleast 3 years. Also since the new 90TB array I added currently has almost nothing on it I have power-management enabled which spins down the drives after 30 minutes which saves a good 120-140 watts of power.
I store a lot of high definition TV shows/movies. I also have a ton of Anime and various asian drama's.
I don't like to delete anything I download as there are many times I feel like watching something again years later. Also I provide access to my friends/family. My internet connection is good enough (75mbit upload) that I can stream pretty much anything over the internet. It is nice because I can watch anything off my machine at my house when I am at my dad's house (We like to watch some TV shows and movies together).
I got a rack because it simply made sense. The high density/high number of hot-swap bay chassis (which I wanted) are rack-mount. I used to just have a rackmount chasis sitting on a dresser or desk like a regular computer for a while. When I bought my house I had several rackmount machines/chasis and I figured I might as well get a rack so I can have things a little better organized. I also spent a little money to convert a few systems into rack-mount. In the end I think it was the right decision.