Hyper-V implementation considerations
Posted by martijnl on December 21, 2008
Last Friday I attended a Microsoft Hyper-V training. It was not the full course with hands-on labs but there was some interesting discussion between presenter and attendees and some attendees already had experience with running Hyper-V in production situations. At the end of the session I had several pages of notes that I have summarized below. As Hyper-V is based on a licensed Xen hypervisor it has an established pedigree but as with all things the quality of the hypervisor alone is not the whole story.
Update: Note the comments from Matt McSpirit in the comments section (I have made some changes to the post to reflect the comments):
Hyper-V pricing was also discussed and I learned some interesting things again. The main thing being that if you want to use the VMware DRS-like “intelligent placement” functionality that you need System Center Operations manager and System Center Virtual Machine Manager. It also turned out that while you get “free” licenses (one with Standard Edition, four with Enterprise Edition and unlimited for Datacenter Edition) to run virtual machines on Hyper-V that this only applies to VM’s that use Server 2008 as their OS. Everything else you still need to have a license for. Which means that if you want to save on licenses that you also need to plan for a migration to Server 2008 for all the servers that you want to virtualize. Edit: As mentioned by Matt it is possible to downgrade a license. I had not found that earlier. There seems to be one issue and that is the versioning of the user CAL’s. Hopefully Matt can clear it up.
Apart from the licensing these are the main points I jotted down during the meeting:
- There is no management interface on the server itself. You can install the server in two ways: as a Core installation or as a Role on top of a normal Server installation. With the Core installation you only have the command line interface (CLI) to manage the server. With the Role installation you can use perfmon and other indicators but like other solutions virtualization with Hyper-V uses a “parent partition” and you can only get environment stats from this parent partition. Management of the server is done from a Windows Vista (with SP1) workstation. Update: When you install the Hyper-V role there is an MMC snap-in available for server management.
- The most stripped down installation of Hyper-V is the Core installation that is downloadable for free from the Microsoft website. This is a 937MB .iso file and it needs 10GB minimum of harddrive space. There has been talk about the hypervisor being 872KB but the hypervisor does not work on it’s own and thus needs an installation of the size mentioned here.
- The free downloadable version is not upgradeable to any other version of Hyper-V. This is in contrast to VMware’s ESXi product which can be integrated into a virtual infrastructure and enabled for Vmotion, DRS, High Availability etc. by letting a vCenter Server manage the box(es).
- If you want to have all the performance advantages offered by the “enlightenments” or para-virtualization of the OS than you are bound to either Server 2003 R2 or Server 2008. Other OS versions do not support these enlightenments.
- Clustering your environment for High Availability is only available in the Enterprise and Datacenter Editions of the software, not in the free version or the Standard Edition.
- To use High Availability your storage solution needs to support SPC3 commands. This is a function that has only been recently implemented by storage vendors. At the training there was a comment by another attendee that there are many storage arrays that did not support these commands as early as a year ago.
- Like VMware VMotion requires vCenter Server Hyper-V Quick Migration requires System Center Virtual Machine Manager.
- Live Migration is planned for Server 2008 R2 which is currently planned for a Q1 2010 release (possibly earlier as mentioned in this ZDNet article).
- Updating of templates or servers that are stored but offline can be done through System Center Virtual Machine Manager with the Offline Virtual Machine Servicing Tool. Updating of the actual server is done through WSUS or System Center Configuration Manager. This means that you have to be using one of either technologies for your current patchmanagement.
- Technologies like the Distributed Virtual Switch that is announced for VMware’s next version have not been announced for Server 2008 R2. This means that currently you have to align your vSwitch configuration on all machines. I have not found it yet but I expect this can be done through a PowerShell script which should make life easier.
- Virtual Switches in Hyper-V support only one VLAN per virtual switch. Because it is not possible to have multiple virtual switches controlling the same NIC’s you have to plan for at least one physical network card per VLAN. Edit: It seems that what was described was the way to configure a VLAN for the Parent Partition. See this writeup on VLAN settings in Hyper-V.
- Bonding or teaming is not supported for an iSCSI storage network.
- Resource allocation is handled at the Virtual Machine level, not at a centrally managed location. At the training it was not mentioned if you can manage your resource pools in combination with System Center Operations Manager.
- As mentioned earlier, there is a Core installation and a Server Role installation. Keep in mind that with the Core installation you will not have the possibility to use Powershell scripts. This is only available when the full server functionality has been installed.
As far as an idea about the practical use of Hyper-V in a production environment you will find a number of potential disqualifiers in the list above. There were two attendees already using Hyper-V in production environments and these were both IT firms that handled server management for clients. One of those mentioned that the network issues in Hyper-V prevented them from deploying it further.
If you are planning a Hyper-V deployment or are making a comparison between different virtualization vendors this information will hopefully help you in making the decision.