Which is why designing for scale is so important. I don’t believe any startup “needs” to achieve anything more than around 2 9s of uptime, which is what a properly configured server should do for you. However, even at the beginning, you need to be coding and planning for growth.(emphasis mine)
Small things like managing how transactions occur, having separate database connections for reading and writing, making your app able to handle variable state sessions, etc are key.
One of his posters, Ian Holsman, responds:
The reasoning behind not worrying about scaling is that in a lot of cases people worry about the wrong things. They will spend hours getting that code tuned just so, and have it running in 10ms less time, only not to realize that the code is only run once a day.
Scott Sanders from Feedlounge also responded:
The FeedLounge development process was more along the lines of:(again, emphasis mine)
1. Build a webapp, see if the features are compelling to a set of users, keeping a design in mind that is capable of scaling
2. Overrun the shared server that you are using, switch to dedicated server, so you can properly measure the effects of the application.
3. Add more users, adding requested features from the users, measuring the load in a fixed, known environment, and start work on “Distributed” part of ladder. The is where the build portion of the scalability starts.
4. Now that you believe you have something that has value, invest in the hardware and software development necessary to scale. Continue working on priority based tasks towards release of your product.
Scott's point is valid, and the italicized portion makes it valid: you need to be designing your software so it's capable of scaling. No, Ian, this doesn't mean spending weeks optimizing the code to trim every last microsecond off of every transaction. It means designing your software well from the beginning.
Most importantly, it means acknowledging the possibility, however remote, that you may actually succeed and build something that people eventually use. Many people.
This point applies equally to those designing web sites and those planning on deploying SaaS. If you are going to make it available on the web, and you're not designing for scalability, then you just aren't planning for success: you're planning for failure.
Ian does make one point validly: in the beginning, you can't spend too much time on scalability. You need to make sure you get the <content, features, service, whatever> right. But you need to be prepared for scaling; that's why it's important to choose a toolset in the beginning that makes scaling later as easy as possible.
Plan on succeeding.
As a product manager, I'd be remiss if I didn't point out that that is exactly what we designed our SDK for--so developers can spend their time in their area of expertise, but have a framework underpinning their software that will scale when the time comes.