If you are thinking about scaling a web application or service, congratulations, because you have users that liked you or were curious enough to sign up and stick around! You will of course be acquiring more users shortly.  While the trajectory of user growth is unknown, and depends a lot on your usage model (viral social network vs. word-of-mouth individual user service) there are a few things you need to address:

1. Capacity – your site will need to handle more concurrent users, signing up users alone can generate a lot of load on the system, even before they get to using the product.
2. Reliability – users will want to use the service on their own time.  The site needs to be up and running 24 hours with  limited maintenance windows.
3. Scalability – if users can generate data on your site you will have more data you need to store/retrieve.

If you’re growing too fast a common way to solve #1 and #3 is to throw hardware at the problem.  A startup focuses on creating the MVP (minimum viable product), which means the prototype has just enough functionality to add a significant value to the lives of users that convinces them to sign up and use it for awhile.  Putting the product out there initially means you’re testing the product/market fit, and as a result you’re unsure of how many user will signup, and what their usage patterns will be .  Let’s say you are a cocky and a cheapskate, you know you’ll have users, but you don’t want to solve problems by buying hardware all the time.  If you’re cautious you will do the following:

1. Start performance tuning and load testing even before releasing the product!
2. Create a restricted alpha and beta, which allows you to control the growth rate.
3. Measure the adoption rates and usage patterns for your alpha and beta users.
4. Use the measured adoption rate to anticipate how many servers you can afford.
5. Monitor spikes in adoption due to press releases or other news events. And be ready to re-route traffic (failover) in the event of a server failing.

These are the top 5 ways you can initial think about scaling your app without a whole lot of code re-writes.  But there will come a time in which you will need to redo a lot of the prototype’s code base.  We’ll save that for another post…