Today we are announcing the public preview of upgrade policies for Virtual Machine Scale Sets with Flexible Orchestration. Upgrade policies allow for more granular control over the upgrade process, ensuring that your services remain available and responsive during updates.

Automatic upgrade policy

With an automatic upgrade policy, the scale set makes no guarantees about the order of virtual machines being brought down. The scale set might take down all virtual machines at the same time to perform upgrades.

Automatic upgrade policy is best suited for DevTest scenarios where you aren’t concerned about the uptime of your instances while making changes to configurations and settings.

Manual upgrade policy

With a manual upgrade policy, you choose when to update the scale set instances. Nothing happens automatically to the existing virtual machines when changes occur to the scale set model. New instances added to the scale set use the most update-to-date model available.

Manual upgrade policy is best suited for workloads where you require more control over when and how instances are updated.

Rolling upgrade policy

With a rolling upgrade policy, the scale set performs updates in batches. You also get more control over the upgrades with settings like batch size, max healthy percentage, prioritizing unhealthy instances and enabling upgrades across availability zones. Additionally, Rolling has the option to enable MaxSurge. MaxSurge deploys new instances running the latest model to replace instances using the old model. MaxSurge allows customers to maintain their full scale set capacity during the upgrade process, ensuring the entirety of their scale set is available to receive traffic

Rolling upgrade policy is best suited for production workloads that require a set number of instances always be available. Rolling upgrades is safest way to upgrade instances to the latest model without compromising availability and uptime.

Key Benefits

Keep scale set instances up to date and secure without impacting availability
Choose an upgrade policy that best fits your workload
Change and modify your upgrade policy at any time
Spend less time manually managing the upgrade process

Setting the Upgrade Policy

The upgrade policy can be set during scale set creation or change any time post creation. If you do not explicitly set an upgrade policy, it will default to manual.

During the Virtual Machine Scale Set creation in the Azure portal, under the Management tab, set the upgrade policy to Rolling, Automatic, or Manual.

Alternatively, for existing Virtual Machine Scale Sets, select the Virtual Machine Scale Set you want to change the upgrade policy for. In the menu under Settings, select Upgrade Policy and from the drop-down menu, select the upgrade policy you want to enable.

If using a Rolling Upgrade Policy, you can configure additional settings such as batch size, max unhealthy percentage or opt to use MaxSurge which will help to ensure your application remains fully up and running during the upgrade process.

Available Now

Upgrade policies for Virtual Machine Scale Sets with Flexible Orchestration are available in all public cloud regions. To get started, see Upgrade Policies for Virtual Machine Scale Sets.

Micah McKittrick

Microsoft Azure Compute Services
Senior Product Manager

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