Microsoft will be rebooting a large number of VM's across several Azure regions on Tuesday, 9th January.
Further to Microsoft's recent annoucement (scroll down for details), we recommend that you check the planned maintenance section of your service health dashboard within your Azure environment as soon as possible, to see which, if any, of your services may be affected. With the correct action upfront, you can avoid unexpected downtime for your services.
Please note this is not a new practice by Microsoft and certainly not a reason to dismiss Public Cloud IaaS.
Seasoned Azure Admins will be familiar with the reasoning behind reboots in Azure. From time to time, Microsoft need to patch the underlying infrastructure - or even migrate services to new hosts. We hope this will become an invisible task to customers one day, but currently can get around it with availability set clustering of VM's or a timely proactive-redeploy of VM's, before Microsoft do it for you.
If you have any questions on this, please reach out to email@example.com or contact your Account Manager.
-- Original communication from Microsoft --
Performance, security, and quality are always top priorities for us. I am reaching out to give you an advanced notice about an upcoming planned maintenance of the Azure host OS. The vast majority of updates are performed without impacting VMs running on Azure, but for this specific update, a clean reboot of your VMs may be necessary. The VMs associated with your Azure subscription may be scheduled to be rebooted as part of the next Azure host maintenance event starting January 9th, 2018. The best way to receive notifications of the time your VM will undergo maintenance is to setup Scheduled Events.
If your VMs are maintained, they will experience a clean reboot and will be unavailable while the updates are applied to the underlying host. This is usually completed within a few minutes. For any VM in an availability set or a VM scale set, Azure will update the VMs one update domain at a time to limit the impact to your environments. Additionally, operating system and data disks as well as the temporary disk on your VM will be retained during this maintenance.
Between January 2nd and 9th 2018, you will be able to proactively initiate the maintenance to control the exact time of impact on some of your VMs. Choosing this option will result in the loss of your temporary disk. You may not be able to proactively initiate maintenance on some VMs, but they could still be subject to scheduled maintenance from January 9th 2018.
Here is a list of resources that should be useful to you:
• Planned maintenance how-to guide and FAQs for Windows or Linux VMs.
• Information about types of maintenance performed on VMs.
• Discussion topics for maintenance on the Azure Virtual Machines forums.
- By Sami Ozturk (Cloud Solution Specialist)