Posterous chooses The Rackspace Cloud over Amazon
rackspacecloud.com
rackspacecloud.com
This is a pure PR puff piece.
Why is this even on HN in the first place?!
I used to spend a lot of time with EC2 deployments dealing with attaching EBS volumes, then starting services that required the EBS volumes (though I finally got this down pat).
It inspires me that we have these cloud services at our disposal. And maybe Posterous (and many other great startups) would not have been conceived without the founders having access to such technology.
Whether you lease or buy your servers, if you have a > 30% 'on' pattern and use anything but trivial bandwidth then using a cloud instead is very expensive.
Sure you can instantly call up more instances, but there are only a limited number of cases for which that is true, and almost none of them involve web based services (which are pretty much 'on' all the time, with some fluctuations because of the day/night shift).
Building fault-tolerance (like S3/EBS do) is a HARD problem. That's worth paying for.
Once you move your data to the cloud for reliability, you almost have to move the processing close to the data to get acceptable performance.
The 400% jump in video utilization upon the release of the iPhone 3gs probably represented a major inflection in their rate of storage growth, and their peak need for media processing capability. That may have been something they could have anticipated, but it would have been easy to end up dramatically over- or under-provisioned.
In addition, I'd expect that their load varies a lot. Some of it may be predictable, but short lived (like increased photo and videoposting around the holidays), so renting 2x as many servers for a week a few times a year seems like a hassle. Other spikes are going to be unpredictable and of unknown duration. Keeping too much extra capacity around for these situations can quickly eat up the savings from renting servers.
At the very least, "cloud computing" is going to be valuable for handling large peaks, even if they have some more permenant infrastructure in place. Look at electrical power generation. Utilities invest heavily in steam plants to achieve high efficincies andclow costs for meeting their base load. To meet peak demand, they fire up less efficient gas turbines. The higher operating cost is more than offset by the fact that they are so much cheaper to build and can be spun up and down quickly.