Hyper-V Live Migration

Well Microsoft Hyper-V has been around for a little while now and has been playing the catchup game. However the release of Server 2008 R2 sees the introduction of features previously only available from other vendors.

One such feature is Live Migration, the ability to move a Virtual Machine from one Host to another without turning the guest off. Coupled with a case study deployment of Direct Access I got the opportunity to complete an implementation of Live Migration with great success.

Things I have learnt;

• There's a lot of useless information around for Hyper-V - I'll try not to add to it :)
• Hyper-V and Hyper-V R2 are quite different, dont expect them to behave the same.
• DO NOT team network cards - As of today (04/09/09) teaming is not supported, and when it is, it will be up to the vendor to provide and support any teaming of NICs.
  Update: This has changed. Check this post for details.
• You'll need more NICs - Hyper-V loves network cards. 2 teamed for production (when it actually works), 1 for heart beat, 1 for live migration traffic and 1+ for iSCSI, if you use it.
• You'll have to rethink your SAN - Cluster Shared Storage require a witness disk for the quorim data, and you can't store anything else on it. So plan to setup a new vDisk from your SAN at around 250 -> 500MB.
• You'll want more resources - One of the really appealing aspects to Live Migration is the ability to setup an N+1 High{ish} Availability Cluster, but that means the nearly 90% utalization you are currently running your poor, innocent hosts at, isn't going to do. Plan / Budget for it.

Server 2008 core

It is a huge pain. I do like working on core though, it feels (excuse the pun) hard-core, but it does make managing the hosts hard. Unless you are going to implement Virtual Machine Manager (which I do recommend btw) you aren't going to be able to do all the thing you want to within core. Troubleshooting is also made substantially harder.

The big appeal is of course the smaller footprint Core has - though dont expect some magic performance boost by just going to core.

That being said, I'd implement Hyper-V on 2008 Core whenever I can - it just seems appropriate.

As for your guests - You'll need to re setup their networking, moving to R2 will install new networking hardware with nice fresh DHCP settings [maybe an oversight from Microsoft but no biggie]. Just remember to record them before hard.

Micosoft Cluster Shared Storage

I've kept this seperate as it is required by Hyper-V Live Migration but IS NOT part of Hyper-V.

This means you should consider it seperately and carefully.

You'll need a static IP and hostname for your Cluster when you create it, you'll need to configure the Witness disk mentioned earlier and you'll need to seperate the heart beat, production and Live Migration network all setup in Cluster Manager.

TIP: Moving an already NTFS formatted disk to Cluster Shared Storage does not destroy the data. Be sure you have backups though.

Installation Order

Do things one at a time and test them carefully and you wont go wrong. - Measure twice, cut once and all that.

1. SAN - Create the Witness Disk, Virtual Machine storage, LUNs etc
2. Server 2008 R2 - Install the base OS, if at all possible stick with the Windows Drivers (I'd only use vendor drivers after careful testing) *See below for Core
3. Networking - Assign your IPs, Name your NICs, test connectivity between all hosts and SAN [iSCSI]
4. Storage - Connect to the SAN, check all the drives appear and make sure they have the same drive letters on all hosts.
5. Clustering - Install MPIO and Clustering. Create your cluster, give it its IP and hostname, check your hosts and networking appears corrently. Configure your witness disk.
6. Hyper-V - Install Hyper-V, configure all networking, dont create Guests!
7. Live Migration - Enable Cluster Shared Storage and add your disks (No, not the witness disk)
8. Add/create your Virtual Machine using Cluster Manager.
9. Check their configuration using Hyper-V manager.
10. Start your Guests using Hyper-V manager.
11. Migrate your Guests using Cluster Manager.

Well thats all for now, have fun with Virtualization. It's powerful technology but there's a lot of room to break things, so please be careful.

Footnote about Server 2008 Core:

There's a lot of good info online about the basic setup of core as well as a few mini GUI tools to download. Check out http://www.petri.co.il/configuring-windows-server-2008-networking-settings.htm

One thing I'd recommend is get remote management working and do as much as you can from your Windows 7 management machine.

Update: As for this past weekend (12/10/09) I've managed to get NIC teaming working with Hyper-V. Have a read.