Microsoft Azure Reservations are a way of pre-paying for an Azure resource over a one or three-year term to get the most cost-effective pricing. The Reservations family continues to grow: it started with Reserved Instances, a way of pre-paying for Azure virtual machine base compute, and was extended with Reserved Capacity, a way of pre-paying for Azure SQL Database compute capacity. In 2018, Software Reservations for SUSE Linux software and Reserved Capacity for Azure Cosmos DB throughput were added to the family.
Now the family also includes Microsoft SQL Data Warehouse Reserved Capacity. Microsoft SQL Data Warehouse Reserved Capacity allows customers to buy compute Data Warehouse Units (cDWU) with either 1-year or 3-year options for discounts of up to 65%. Reserved Capacity can be shared by multiple warehouses in the same region and there are exchange and cancel options available if business needs change. Additionally, there are new RedHat Enterprise Linux Software Plans where the rules are stricter in terms of exchanging and cancelling, but discounts of up to 18% are still available.
For further information on Microsoft SQL Data Warehouse Reserved Capacity, please visit https://azure.microsoft.com/en-us/blog/azure-sql-data-warehouse-reserved-capacity-and-software-plans-now-generally-available/.
The following link gives you an overview of Reservations and if you expand the “Buy a reservation” link at the left you can get details on the current five members of the Reservations family: https://docs.microsoft.com/en-us/azure/billing/billing-save-compute-costs-reservations.