What You Must Know About Hyper-V
The good news is that there is now a lot of fantastic information out there on Hyper-V. The bad news is that there’s so much, it can be hard to know where to start. So, we’re going to help you out a bit with a simple list of the things that you must know and that you have to get right — not just from a technological standpoint, but also so you can effectively communicate with others in the Hyper-V community.
What follows is a collected wisdom of the experiences of many Hyper-V administrators who have gone before and learned by trial.
Terminology and Concepts
- Hyper-V is available in three distinct packages.
- A standalone product called Hyper-V Server. This product has no licensing costs. It also has no GUI.
- A role inside a fully licensed copy of Windows Server 2012 Standard Edition or Datacenter Edition.
- An installable feature of Windows 8 Pro.
- There is no product called “Hyper-V Core” and the term is completely meaningless. Hyper-V can be installed as a role inside an installation of Windows Server running in Core mode. This is called “Windows Server 2012 with Hyper-V”, just as it is when installed inside a GUI.
- When Hyper-V is enabled, it becomes the kernel. Windows becomes the “management operating system” (term that Microsoft documentation uses). It is also referred to as the “host operating system” or the “parent partition”. This is a special-case virtual machine that has some unique properties and features, such as the ability to communicate with and control the hypervisor. Hyper-V Server installs a stripped-down version of Windows Server that has no available roles and features beyond those required for servicing Hyper-V guests.
- If you don’t understand the Hyper-V virtual switch, don’t even get started until you do.
- “C” power states are bad. Get into your BIOS and disable them. Each BIOS is different. Especially watch for C1E.
- If any of your storage doesn’t support offloaded data transfers (ODX), disable it at the first sign of storage troubles (section 3). As of now, Windows/Hyper-V Server 2012 tries to use ODX on everything, even if it doesn’t support ODX. A hotfix/patch is on the way to change this.
- Pass-through disks don’t really perform better. Most experts will tell you not to use them at all.
- Guest operating systems must all boot from a virtual disk on the virtual IDE chain. The page file for Windows guests must also be on a virtual disk on the virtual IDE chain.
Software and Patches
- You need a copy of Windows 8 or Windows Server 2012 to remotely manage Hyper-V Server 2012. If you don’t have those, you can always RDP to the management operating system and manage it that way.
- Stay abreast of updates, even those that aren’t yet in the main update branch.
- Until it finds its way into a mainstream patch roll-out, KB2813630 should be installed on all Hyper-V Server clusters.
- The Server Manager in Windows Server 2012 has a built-in Best Practices Analyzer for Hyper-V. Let it help you.
- Microsoft publishes the Microsoft Assessment and Planning Toolkit for free. Too many people either dramatically overestimate their need for storage and networking horsepower or listen to inexperienced people on Internet forums proclaim that absolutely every Hyper-V deployment must have RAID-10 and 10GbE, and waste a lot of money as a result. MAP can help you avoid that.
- Don’t use teaming for iSCSI and SMB 3.0 connections to storage. Multipath I/O (for iSCSI) and SMB Multichannel are both free.
- VMQ is really helpful when it works, and crippling when it doesn’t. It’s on by default, so if your virtual machines are suffering with terrible network performance, try disabling VMQ on physical adapters before performing a lot of extensive troubleshooting.
- Update the Hyper-V Integration Services in every Windows guest and keep them updated.
- Getting to many advanced features, like multiple virtual network adapters for the management operating system, requires PowerShell.
- Teaming in Windows/Hyper-V Server is really cool, and gives you lots of benefits. Unfortunately, using it cuts off a few enhancements for virtual adapters attached to it, specifically RDMA and SR-IOV.
- Virtual adapters themselves don’t have all the features of hardware adapters, specifically RSS.
- “Management traffic” refers to network traffic that is intended only for the management operating system. It includes remote desktop connections, connections from management tools like Hyper-V Manager and System Center Virtual Machine Manager. It is also the path that network backup tools will operate on. It includes Windows Update downloads, either from Microsoft or an internal WSUS system. Essentially, management traffic is all traffic that is not specific to virtual machines or operation of a failover cluster that the Hyper-V Server is a member of.
- For standalone hosts, put management traffic on its own physical adapter. Have another for the virtual machines to use.
- Disable DNS registration on all management operating system adapters aside from the management adapter.
- If you’re not using IPv6, disable it, especially in a cluster.
The purpose of this list is to provide a very fast read on what you need to know and do. Where possible, I have provided links to one-shot explanations of an item. I have intentionally not expounded on any of these so as to make the material easily digestible. If there are any subjects that are a real hang-up, please let us know. We’d be happy to provide detailed postings on anything that people are struggling with.
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