One of virtualization's best features is that it can easily perform host maintenance. Learn how Hyper-V works and when to use it.
Many Hyper-V and vSphere terms are similar and easy to figure out regardless of your background (mine is primarily in VMware products). One such concept is host maintenance mode, which requires System Center Virtual Machine Manager (SCVMM) to be in place because it is not supported on standalone hosts using Hyper-V Manager. The basic premise of Hyper-V maintenance mode is to remove all running (and powered off) virtual machines from the host. Hyper-V host maintenance mode is excluded from new PRO ratings that will aid in future placement or other migration options.Selecting a host to put in maintenance mode is quite easy via a right-click on the host in question. Figure A shows the quick menu that appears. Figure A
Click the image to enlarge.The option to do a live migration is much more attractive for any virtual machines running on the host. Once the migrations are launched to the host, the tasks are underway and can be viewed in the jobs window within the SCVMM console. The host going into maintenance mode is shown in Figure B. Figure B
Click the image to enlarge.
Entering maintenance mode is painless, and from there, you can do work on the source host. In the example above, a failover cluster leveraging Clustered Shared Volumes (CSV) allows the virtual machines to reside on a shared storage resource yet have a local path. The CSV path is c:\ClusterStorage\Volume1 by default.
For me, the clear use case for Hyper-V host maintenance mode is Windows Updates. Though you can use the Hyper-V "only" operating system (which is, in my opinion, just a further stripped down core installation that permits the Hyper-V role), I think we are better off with a full installation of Windows. This is specifically for troubleshooting reasons. In both cases, the Hyper-V server will need Windows Updates applied.
Have you used Hyper-V host maintenance mode? If so, why do you use it? Share your comments in the discussion.