At PDC10 Microsoft announced a new Compute Instance Size: Extra Small. Previously, there were four Azure Virtual Machine Instance sizes: Small, Medium, Large and Extra Large, each with its own price and resources. The standard price for an Extra Small instance is $0,05/hour (to compare, the Small VM costs $0,12/hour). What you get for this price is not a lot as you can expect:

• 1 x 1GHz processor
• 768 MB memory
• 20GB storage
• 5Mbps network bandwidth

These low resource levels are achieved by having multiple XS VMs share resources on the same node.

In my opinion the new XS VMs are interesting for two reasons. First of all, they’re ideal for testing purposes. Individual developers can get there own Windows Azure account and use it to deploy only XS instances. A few days ago I deployed an ASP.NET MVC app to four XS instances. After confirming everything worked, I removed the hosted service and the whole excercise cost me just $0,20.

A second reason this may be interesting is when you have a large workload that you can divide over a (very) large number of nodes. Suppose you have a workload that can be divided into 1000 chunks. Using 1000 Extra Small instances will cost you $50,00 per hour, using the same number of Small instances will cost you $120,00 per hour.

Deploying Windows Azure roles to Extra Small VMs is really easy. Just like the other VM sizes you select it in the role’s property panel: