The on-demand disk pattern is similar in nature to the scale up pattern, in that it operates on an already running instance and requires some downtime. This pattern is a manual process and might be avoided in automated processes such as the scale out pattern, as the downtime involved might cause alarm or scaling policies to trigger, causing some unwanted side effects.

The benefit of on-demand disk size is that you do not need to plan ahead for disk resources. Once the instance is running, you can simply resize its volume when it gets to its maximum capacity. Another example would be in the event where your application is very I/O heavy. At first your instance performs very well, but over time, with increased usage, the I/O operations take longer. An easy way to get more performance out of the base volume might be to enable RAID and stripe the volume.

First we will launch the AWS Linux AMI with an additional 20 GB EBS volume. Ensure that the Volume Type is Magnetic and...