Microsoft has just released the fourth Technical Preview of Windows Server 2016. Among the new feature introduced, Hyper-V is the main one with network adapters and RAM hot add, new Check Points, nested virtualization and a direct Container management feature. Windows Server now support hybrid clusters with Server 2012 R2.
It’s now possible to add RAM memory and network adapters in hot mode, that is, while the VM is powered on without incurring in any downtime at all. RAM can be hot added only if the Dynamic Memory option wasn’t selected while creating the virtual machine itself.
The PowerShell Direct feature allows to run commands from host to guest without realizing a direct connection between the two or creating dedicated firewall rules, and regardless to the host connection mode (direct or remote). The virtual machine must have Windows Server 2016 TP4 or Windows 10 as operating system; naturally you must be logged as Administrator on the host and have access credentials to the guest VM.
Guest Additions, the optimization toolset akin to VMware’s VMware Tools, are now available as a simple update to be installed on Windows operating systems; for the installation on Linux and FreeBSD, please consult this TechNet article.
The vmguest.iso file is no longer available.
Production Checkpoints (PC) are a new type of Hyper-V snapshots that allows to create a “point in time” image of a Virtual Machine, ie, a checkpoint instead of a recording of the state; PCs are created using a backup technology inside the the guest OS: in Windows it’s Volume Snapshot Service (VSS), in Linux the file system’s buffers are cleared to create consistent checkpoint at the file system level. Anyway, it’s possible to used checkpoints based on saved states; PC is the default snapshot mode.
An host with Server 2016 TP4 can now be added to a cluster with Server 2012 R2 hosts, however it will work with the same set of features available for Server 2012 R2; in other words, the new features introduced will not work. These will be available once the upgrade of the whole cluster (and of VMs with the dedicated cmdlet) to Server 2016 will be performed.
As far as virtualization with Hyper-V is concerned, there are some important news. First, there are new formats for configuration files of VMs: .vmcx for configuration data and .vmrs for run state data. These two new files have been conceived to guarantee a better efficiency in writing and reading operations of configuration data and to reduce the problems caused by corruption after a storage failure; both are in binary format, so direct editing (as for VMware’s .vmx config files) is not an option.
Finally nested virtualization available, that is, creating a VM inside a VM, but with a few caveats: only Intel processors with VT-x technology and Windows Server 2016 Technical Preview 4 or Windows 10 build 10565 operating systems are supported.
Lastly, Containers (a topic we’ve covered in this article) can now be managed with Hyper-V and not just an additional service available with Server Manager. It’s worth a mention that now you can manage from a single interface all versions of Hyper-V: 2012, 8, 2012 R2, 8.1 and 2016.
This release has a few problems: the Edge browser can’t be used if logged as Administrator, some shortcuts might not appear in researches and the first loon might take even a minute; next ones will be quicker.
Windows Server 2016 Technical Preview is available at the Microsoft official website and this article of the TechNet offers additional information about this release.