The day has finally come. You're the VMware person, but your boss has asked you to take a look at Microsoft virtualization.
He's got it all worked out for you; you're going to be his all-around, multi-platform virtualization person! Don't despair: Mike is here and going through the same learning curve. So here are my top tips (or is that gotchas?) when it comes to building a Hyper-V infrastructure.
Use the Server Core edition
It is possible to enable the Hyper-V role either in the fully blown version of Windows 2008 R2 or in Server Core. I would recommend you always use the Server Core edition of R2 for the Hyper-V role. You can do it very easily from a command prompt using:
start /w ocsetup Microsoft-Hyper-V
Server Core only requires 512MB of RAM to function, compared to the normal 2GB or 4GB for other flavors of Windows. As such, it reduces the amount of patching needed, as well as the overall attack area. Whilst the Server Core edition is in no way as slim as, say, VMware ESXi, it's still worth using the slimmest build possible to get a really bare bare-metal hypervisor up and running.
Using Hyper-V on Server Core offers unique challenges, given its lack of a GUI front end, but for those with VMware experience, getting your head around command-line utilities may not necessarily be the challenge that it is to other administrators.
Virtual switches are different
If you are used to vSwitches in VMware ESX, you know they have built-in teaming features, which very easily allow you to patch more than one physical vmnic to a vSwitch.
The same is not true of Hyper-V, which essentially uses hardware manufacturer-specific tools. So it's important to install the vendor drivers for your physical network interface cards (NICs) and create NIC teams at the Hyper-V level before presenting these bonds to the vSwitch -- and to use the vendor's own management tools.
Just as with VMware, your physical switch will have to support the appropriate protocol and be enabled for that protocol, too. Given the challenges of the network layer with Hyper-V, if your project with Microsoft virtualization is a new one, it might be an ideal time to consider the new converged networking or virtual I/O systems. These allow for two 10GB or 20GB adapters to be teamed by the network consolidation system, with the bandwidth being carved up at the hardware layer.
Plan for more physical RAM
Hyper-V does not currently support memory overcommit. Microsoft has promised to introduce a feature called Dynamic Memory in Service Pack 1 for Hyper-V R2, but at this stage it's not 100% clear whether Dynamic Memory will have the same functionality as VMware's much-vaunted memory overcommit. The message from Microsoft is that Dynamic Memory addresses the same problem, but in a totally different way.
In the meantime, imagine that in the world of Hyper-V, when you allocate memory to a virtual machine (VM), it is exactly like setting a reservation in VMware. So if you create a 4GB VM within Hyper-V, when you hit the power button for that VM, there must be 4GB RAM available on the physical machine, regardless of whether the VM needs it or uses it. For this reason, you will need more RAM to get the same consolidation ratios as you do with VMware ESX.
With luck, by the end of the year, you will be able to squeeze more capacity out of the Hyper-V host. (I'm not making a cheap shot here at Microsoft, by the way. Everyone always runs out of memory before they run out CPU cycles when they virtualize. The more memory you can afford in a single host, the better.)
Use the Datacenter Edition when possible
Selecting the right version of Windows is also pretty critical. I consider it a best practice to use Windows Server 2008 R2 Datacenter Edition. The 64-bit edition supports up to 64 logical CPUs, 2TB of RAM and 16 nodes in a cluster. But the main reason for selecting the Datacenter Edition is that it allows for an unlimited number of VMs from a licensing perspective. Many of the larger VMware shops have switched to using the Datacenter Edition for this very reason. If you are one of them, then you are already covered.
Use the Best Practice Analyzer for Hyper-V
Recently Microsoft released a Best Practice Analyzer for Hyper-V. For years my students have moaned about how they really could do with some kind of sanity checker for their VMware ESX builds. The nearest VMware has is the Host Profiles compliance check and the ConfigControl system, neither of which are free.
The Microsoft utility is not as comprehensive or functional as ConfigControl, but it is at least a free download. The utility integrates with Server Manager and allows you to exclude lists of best practices that your organization may not necessarily follow because of your own unique business practices. You can get these kinds of analyzers for all manner of components within Windows Server 2008, so even if you're not using Hyper-V, you may still find them useful.
Use Cluster Shared Volumes for HA
Few organizations would consider using a virtualization platform without some kind of high-availability solution in place. If you are used to VMware's Distributed Resource Scheduling and High Availabilty and want the same feel and experience in Hyper-V, Cluster Shared Volumes (CSV) is the way to go.
CSV is not mandatory for a feature like Live Migration on Hyper-V, but without CSV there is no other easy way to protect a VM from the failure of a physical host. In the original version of Hyper-V, you literally had to create one VM per volume -- yes, I know it's crazy, isn't it? -- but fortunately Hyper-V R2 dispensed with this limitation.
Explore Hyper-V management tools
It's a common misconception that your management options are limited on a Microsoft virtualization platform. There are loads of free utilities that can help manage Hyper-V, and in some cases they actually supplant the management tools that are part of the Microsoft stack. I have in mind two such utilities: HyperV_Mon and Citrix Essentials for Hyper-V, Express Edition.
HyperV_Mon monitors physical, logical and virtual performance information and displays it in an easy-to-understand graphical interface. Detailed text displays also highlight other performance issues, such as memory, paging and I/O. And the tool also provides information about virtualization overhead within VMs. Many people rate HyperV_Mon higher than the built-in monitoring tools that ship with Hyper-V.
Citrix Essentials for Hyper-V, Express Edition allows you to manage two Hyper-V hosts connected to the same storage array. It ships with Citrix StorageLink technology, which enables the provisioning of iSCSI and Fibre Channel storage and facilitates the Site Recovery Express Feature. The real downside of the Express Edition is that it is limited to a two-node Hyper-V environment, but it is a good way of dipping your toe into the water.
If you're a VMware person who is being asked to use Microsoft virtualization, don't be too disheartened. Try to see it as yet another skill you can develop. The more you know about VMware, Microsoft and Citrix Systems' virtualization technologies, the greater your job security! Plus, it puts you in the driver's seat when it comes to discussing licensing and pricing -- and allows you to do your own comparisons, rather than being mired in the deluge of vendors' fear, uncertainty and doubt.
About the expert
Mike Laverick (VCP) has been involved with the VMware community since 2003. Laverick is a VMware forum moderator and member of the London VMware User Group Steering Committee. Laverick is the owner and author of the virtualization website and blog RTFM Education, where he publishes free guides and utilities aimed at VMware ESX/VirtualCenter users, and has recently joined SearchVMware.com as an Editor at Large. In 2009, Laverick received the VMware vExpert award and helped found the Irish and Scottish VMware user groups. Laverick has had books published on VMware Virtual Infrastructure 3, VMware vSphere4 and VMware Site Recovery Manager.
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