News

Hotpatch Released for Windows Server 2022 Datacenter Azure Edition

• By Kurt Mackie
• 02/16/2022

Microsoft on Wednesday announced the "general availability" commercial release of its Hotpatch capability for virtual machines, which just works with the Windows Server 2022 Datacenter Azure Edition product.

The Windows Server 2022 Datacenter Azure Edition product is obtained via the Azure Gallery and became commercially available in November. The Datacenter Edition is described as "a special version of Windows Server built to help you use the benefits of the cloud in combination with Azure Automanage for Windows Server."

Hotpatch and Reboots
Hotpatch is a capability of Azure Automanage, which helps automate virtual machine management tasks in accordance with Microsoft's best practices. Organizations can use Hotpatch to automatically apply hotpatch updates to virtual machines, without reboots, because the patching occurs in memory. Applications continue to run without interruptions, even when Hotpatch is installing updates.

In actuality, reboots are still part of the virtual machine patching process, even when using the Hotpatch capability. Microsoft's announcement and this document explained that Hotpatch just applies security patches that don't require a reboot on top of an Azure virtual machine baseline update (which does require a reboot).

These Azure virtual machine baseline updates are analogous to the Latest Cumulative Updates (security plus quality patches) that arrive on "update Tuesdays" (the second Tuesday of each month) for IT pros that maintain PCs and servers "on-premises."

The Azure Patch Model
The Azure patch model appears to be somewhat different from Microsoft's monthly patch cycle for on-premises machines.

Microsoft releases baselines for Azure, both planned and unplanned, which require reboots. The planned baselines get "refreshed with the Latest Cumulative Update" about every three months. If something unplanned happens, such as a need to fix a zero-day software flaw, an unplanned baseline is applied, which also requires a reboot.

There might be four planned Azure baseline releases in a year (requiring reboots), with multiple hotpatches (no reboots) released in between those intervals.

Even though the Hotpatch capability just applies security fixes, the virtual machine is still kept up-to-date with patches when full baseline releases get applied every three months or so.

Patching virtual machines is a lot faster with the Hotpatch capability, which uses smaller packages. A demo comparing the traditional patching approach with Hotpatch is available in Microsoft's announcement, which offered a patch timing test.

While Hotpatch sounds like an IT pro dream come true, it specifically is only available when using the Windows Server 2022 Datacenter Azure Edition product. It also requires using the Core deployment option with a Generation-2 virtual machine image.

The Windows Server 2022 Datacenter Azure Edition product can be used with Microsoft's Azure infrastructure-as-a-service offering (virtual machines) or with the Azure Stack HCI certified hardware products deployed on premises.

"Windows Server runs best in Microsoft Azure, especially in combination with management capabilities like Azure Automanage," claimed Thomas Maurer, a senior cloud advocate at Microsoft, in the announcement.