New SLAs for Azure VMs

For a while now Microsoft has offered an SLA with service credits for 2 or more Virtual Machines in an Availability Group and also for a single virtual machine with premium SSD based storage. Obviously an SLA doesn’t prevent an outage but it does incentivize the vendor to design their service to avoid outages. The guarantees were:

  • For all Virtual Machines that have two or more instances deployed across two or more Availability Zones in the same Azure region, we guarantee you will have Virtual Machine Connectivity to at least one instance at least 99.99% of the time.

  • For all Virtual Machines that have two or more instances deployed in the same Availability Set, we guarantee you will have Virtual Machine Connectivity to at least one instance at least 99.95% of the time.

  • For any Single Instance Virtual Machine using premium storage for all Operating System Disks and Data Disks, we guarantee you will have Virtual Machine Connectivity of at least 99.9%.

This is the wording in the “SLA for Virtual Machines” v1.8 dated March 2018.

This has been updated as of July 2020 to v1.9 to the wording below:

  • For all Virtual Machines that have two or more instances deployed across two or more Availability Zones in the same Azure region, we guarantee you will have Virtual Machine Connectivity to at least one instance at least 99.99% of the time.

  • For all Virtual Machines that have two or more instances deployed in the same Availability Set or in the same Dedicated Host Group, we guarantee you will have Virtual Machine Connectivity to at least one instance at least 99.95% of the time.

  • For any Single Instance Virtual Machine using Premium SSD or Ultra Disk for all Operating System Disks and Data Disks, we guarantee you will have Virtual Machine Connectivity of at least 99.9%.

  • For any Single Instance Virtual Machine using Standard SSD Managed Disks for Operating System Disk and Data Disks, we guarantee you will have Virtual Machine Connectivity of at least 99.5%.

  • For any Single Instance Virtual Machine using Standard HDD Managed Disks for Operating System Disks and Data Disks, we guarantee you will have Virtual Machine Connectivity of at least 95%.

What’s interesting here is that there is now an SLA for virtual machines using Standard SSD and Standard HDD managed disks.

The connectivity SLA for Standard HDD isn’t great at 95% – this means in a month you could experience 1 day 12 hours of downtime before any service credits were payable… so I wouldn’t advise this for Virtual Machines that you really care about. For Standard SSD however a SLA of 99.5% equates to up to 3 hours 36 minutes of outage per month which may be an acceptable compromise.

This does mean there is now an SLA at a lower price point for Azure Virtual Machines – for example the A_v2 series VMs don’t support premium SSDs so would not previously had a SLA at all but now one is available. This is surely a good thing?

You can read more about the Azure virtual machine SLAs here.

If you want to find out more about how you could benefit from using virtual machines or Azure then give us call.

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