Reserved Instances offer significant savings over Pay As You Go VM’s; typically, you can get a 42% discount with a one year reserved instance and 62% with a three-year reservation. However, how can you save money on VM’s which you only intend to use for a short period?
Azure Automation allows you to automatically shut down and then restart VM’s when required, such as during off-hour periods.
The following features are available with Azure Automation:
- Schedule VMs to start and stop.
- Schedule VMs to start and stop in ascending order by using Azure Tags. This activity is not supported for classic VMs.
- Autostop VMs based on low CPU usage.
Although Azure Automation has been around for quite a while now, most people are unaware of the saving which can be achieved by automating the shutdown and starting of VM’s.
In the below example, I have 2 VM SKU sizes, based in the UK South region, with cost comparison as follows:
- PAYG monthly, based on 730 Hours a month, this is the price most customers are using.
- Monthly cost with 1 year reservation
- Monthly cost with 3 year reservation
- Monthly cost for 310 hours, based on running a VM for 10 hours a day for 31 days.
- Monthly cost for 264 hours, based on running a VM for 12 hours a day, for 22 days.
|VM Size||PAYG Costs Monthly||Monthly Cost 1 Year Reservation||Monthly Cost 3 Year Reservation||310 hours per month||264 hours per month|
|B4MS 4Core 16GB RAM||£102.31||£59.81||£38.43||£43.45||£37.00|
|E4-2as v4 2 vCPU 32GB RAM||£160.23||£94.24||£60.25||£68.04||£57.94|
As you can see, significant savings can be made by automatically shutting down and starting VM’s when not required. In addition, depending on the amount of time the VM’s are running, you can save more money than using Reserved Instances.
Although I wouldn’t recommend using the auto-shutdown and restart on critical servers, they are ideal for test/dev environments.