> No swap on the box.

Wrong.

...some common myths:

1. Swap space does not inherently slow down your system. In fact, not having swap space doesn't mean you won't swap pages. It merely means that Linux has fewer choices about what RAM can be reused when a demand hits. Thus, it is possible for the throughput of a system that has no swap space to be lower than that of a system that has some.

2. Swap space is used for modified anonymous pages only. Your programs, shared libraries and filesystem cache are never written there under any circumstances.

3. Given items 1 and 2 above, the philosophy of “minimization of swap space” is really just a concern about wasted disk space. ...

http://www.linuxjournal.com/article/10678

Edit: formatting

I've heard the "no swap" argument before, but can you explain this a little further?

It seems like there are two potential situations here: 1/ You have swap, you hit swap. Massive slowdown. 2/ You don't have swap, run out of memory and processes die.

#1 is not a good situation, but it seems preferable to #2 doesn't it?

Thanks!

This is a bad metaphor. Utility computing isn't quite up to the same level as electrical utilities. Heroku has suffered from more downtime in the past year than I have power outages. Also, most commercial operations that tap into public utilities have some sort of backup plan for when the power goes out. A dramatic example of that is the power staying on in the Goldman Sacs building during Hurricane Sandy (http://www.inquisitr.com/381743/hurricane-sandy-rages-but-th...)

More visibility would be greatly appreciated into what you're doing behind the scenes and increase your customers' confidence and expectations of using the Heroku pg cloud service. I hope you provide more depth to future answers as opposed to, "Just trust us". I've found that in practice, things never work out that way.

It sounds good until the power grid goes down and the only person in the street with the lights on is with the generator in his garage.

What is your uptime over the last 12 months? As opposed to e.g. the power grid in non-Sandy hit areas?

What if you are a Fortune 500 company, or a part of the government? A defense contractor? Heath insurance provider? I work for a company that does "private cloud", mostly large enterprise/government places that want the flexibility of having their data accessible anywhere, but are not willing or able (for security reasons) to have Amazon or some other provider host their data. If you already have data center infrastructure and expertise in-house, the long-run cost and benefits of buying your own hardware for high-traffic applications can often outweigh renting space and/or paying on a per-transaction basis from AWS. Public cloud is great, but it's not the right solution for everyone.