Reserved instances are a relatively new concept in Azure where you can commit to a 1-year or 3-year term for a virtual machine. By doing so, the price of the VM is heavily discounted (up to 50%). VMs that are consistently up for long periods of time are prime candidates for reserved instances.
Reserved Instances are created for a specific VM size and region. A reservation cannot span multiple regions or multiple sizes.
Reserved Instances are not available for MSDN dev/test subscriptions and may not available for all VM sizes and regions (ex: A-series and G-series are not eligible).
For additional information, refer to Microsoft's documentation article: https://docs.microsoft.com/en-us/azure/billing/billing-understand-vm-reservation-charges
NOTE: Reserved instances use a different permissions model than regular subscriptions. By default, only the user that has created the reservation will be able to see it. As such, it is possible that Overcast recommendations may not 100% represent the actual state of your Azure subscription. The best way to ensure that you can see all reservations is to add the user as Reader to the root management group of your tenant.
To be considered a candidate, a Virtual Machine must fill the following criteria:
- Have 70% or more uptime over the past 3 months;
- Be in a region and of a size that is supported by Reserved Instances.
How to apply
Step 1: To apply this recommendation, click on "View in Portal" to open the Azure Portal.
Step 2: Click on the "Add" button in the top menu.
Step 3: Configure the settings for the reservation. Shared reservations can be used across multiple subscriptions. Alternatively, you can limit the reservation to a single subscription. Please note that reservations must specify Region and VM size.
Step 4: VM usage will automatically deduct from Reserved Instances within the scope. You do not need to do anything else!