Windows – Ruby on Rails on Windows – IIS 7 or IIS 6

You can configure how many Rails processes Apache/passenger spawns. For your size (3 concurrent requests) you should be fine with 2 rails processes:

Set these in your apache config:

PassengerMaxPoolSize 2
PassengerMaxInstancesPerApp 2

The MaxPoolSize determines how many instances can be started maximally, the MaxInstancesPerApp determines how many instances each web-app can have.

You might want to play with:

PassengerPoolIdleTime 

to specify how many seconds an instance must be idle before it is unloaded. Default is 300 seconds.

I run pretty high traffic web application with 3 instances without any problems.

Oh and - the Ruby Enterprise Edition helps too.

I installed 3 instances last night of a vanilla Windows 2003 server. The first two took about 45 minutes, the 3rd, about an hour later, took a full 2 hours before it was ready!

Those had nothing in them at all, without any S3 usage. I doubt there is a way to speed up that fundamental step apart from waiting for Amazon to make deployment speed improvements over time. So, I would conclude that a certain delay is to be expected and Kurt's advice is good, which is to keep 1 or 2 in reserve already prepared.

Another thing you could do is to create a new instance of your AMI type a few times and time it. Then try a few times with your S3 storage and see how much time that adds to it. I assume that the availability zone should match between the image and S3, although I don't know how much time difference that will make.

Once you've determined the max time to provision, keep ahead of the load/usage by that many minutes.