Reducing costs with Azure Spot Instances
When provisioning a new QBS Member in the Development Tier, you have the ability to reduce the costs of your QBS Member by selecting the Azure Spot Instances option.
Azure Spot Instances are a special virtual machine (VM) offering from Microsoft Azure where unused VM capacity is offered to customers at a significant pricing discount.
If VM capacity decreases in the Azure datacenter hosting an Azure Spot Instance, Microsoft may re-claim the Azure Spot Instance for other use, stopping the Azure Spot Instance and evicting the VM. When capacity increases, the Azure Spot Instance becomes available again for use.
For more information about Azure Spot Instances, see Microsoft's documentation.
How QBS manages evictions
When a VM is evicted due to capacity constraints, Microsoft Azure provides the ability for applications to attempt to restart the VM. When a VM impacting a QBS Member is evicted, QBS will continually request to restart the VM every 10 seconds until the request is successful. Once capacity becomes available, the restart request succeeds and the VM restarts.
QBS Members using Azure Spot Instances cannot particpate in a consortium.
When to use Azure Spot Instances
Azure Spot Instances are ideal for development and testing environments where potential intermittent unavailability of the blockchain network is acceptable. QBS production networks that are part of a consortium can't use the Azure Spot Instance feature as the blockchain network ceases to function if the VMs are evicted due to capacity.
The infrastructure costs of a QBS member are primarily the cost of the VMs. By using Azure Spot Instances, you can save over 50% of your monthly costs for a Development Tier member.
For details on estimated cost savings using Azure Spot Instances in QBS, see pricing.