VMM P2V Migration

Microsoft System Virtual Machine Manager (VMM) 2008 R2 includes the ability to do a P2V (physical-to-virtual) migration of Windows computers.  This is usually the last critical step in a normal virtualisation project – take those physical servers that an audit identified as being candidates to be converted into virtual machines.  The process scans the contents of the hard disk and converts them into VHD’s.  The machine specification is converted into a virtual machine configuration.

The first step in all of this begins really when you are doing a feasibility study or sizing your virtualisation hosts and storage.  You’ll run something like Microsoft’s MAP (Microsoft Assessment and Planning) toolkit.  Alternatively if you have already got Operations Manager 2007 deployed then you can install VMM 2008 R2 and wait a while before running the Virtualisation Candidates report.  That takes information from the continuous performance monitoring provided by OpsMgr.  Or you can just run individual performance reports from OpsMgr – but you need to be careful about seeing both the details and the big picture when it comes to a manual interpretation of the statistics.  And be careful about the process OpsMgr uses to store long term data.  Spikes or sudden drops may not be apparent by the data aggregation.

Once you have your Hyper-V 2008 R2 platform and VMM 2008 R2 tested, documented and in production then you can start your P2V process.

Here’s a list of the supported operating systems:

You can use the Microsoft Virtual Server 2005 Migration Toolkit (VSMT) or third-party solutions (cloning, e.g. s/w from Acronis is said to be a successful approach) for converting computers running Windows NT Server 4.0.

As if that isn’t complicate enough then you have to consider how you are going to do the P2V process.  There are two approaches:

• Online: VMM will deploy an agent to the machine to be converted.  This is a temporary installation and does not require a license for the agent.  The agent scans the machine for suitability for an online conversion.  Upon success it will then use the Volume Shadow Copy Service (VSS) to grab file cleanly from the computer to create a new VHD for each disk in the machine.  VSS is used because things like OS files, Exchange files, SQL files, etc can be copied cleanly.  There’s a few catches with this.  (1) Not every version of (older) Windows has suitable VSS support.  VSS is a relatively new technology still.  (2) A P2V conversion is not instant.  It takes time, during which some files, particularly database files like Exchange or SQL will change after they have been copied.  That means the new VM won’t have all the data. (3) Not all server applications, e.g. MySQL or Oracle, have a VSS writer/engine.  They cannot be grabbed cleanly.  Once an online conversion is complete the source computer is left running.
• Offline: With this process VMM deploys a boot image (Windows PE) to the machine to be converted.  The machine is reconfigured to boot from the boot image. The P2V job then runs.  The complication with this approach is that you must ensure that all the required drivers for the original physical machine must be in your boot image.  You can use the “Use storage and network drivers from the following location” option to supply additional drivers.  Because WinPE is used the physical machine must have at least 512MB RAM.

Should you use and online or offline conversion process?

Again, you can use a cloning solution to work with those unsupported operating systems.

Here’s another basic rule of thumb:

• Any machine with static data (web server) can be safely done with an online conversion.  The server stays operational and responsive to users.
• Any machine with changing data (domain controller, Exchange, database, file, etc) should be converted with the offline approach to avoid data loss.  It does mean taking the server offline during an announced outage window.

Is there any preparation work you should do?  Yes.  Remove unwanted files.  Defrag the hard disk (schedule it in Windows Scheduled tasks, e.g. defrag C:).  Finally, remove any hardware integrated software, for example a HP server should have the HP ProLiant Support Pack from the server prior to conversion.  Failing to remove hardware integrated software will cause the new VM to blue screen or have failing services at start up.  You can do a safe mode boot and uninstall the relevant software after the P2V conversion.

When the process runs a new dynamic VHD is created by default for each physical hard disk.  You cannot reduce the size of these disks.  If you need them to be smaller then use a 3rd party solution to do this before the conversion.

When the job is complete VMM will add the Integration Components.

What about a strategy?

• Identify virtualisation candidates.
• Identify required drivers for offline conversions and add them to your VMM driver pool.
• Prepare the physical computer, e.g. do a defrag and double check anti virus, etc.
• Make sure all backups of the physical computer have worked OK and that you can recover from any disaster.
• Maybe do an online conversion to test the process for the server in question.  Place the new VM on a test virtual network.  Make sure it boots up OK and performs OK.  This won’t affect the production physical server.
• Perform final P2V preparations, e.g. uninstall hardware integrated software.
• Perform a suitable conversion (probably offline)of the physical computer.  Leave it offline.  Bring the VM online and test it.
• Put the new VM into production.
• Make sure backups are working OK for the new VM.
• Leave the physical server powered off for a pre-agreed timeframe before removing/recycling the physical computer.  You never know what will happen, e.g. require a

reversal of the process to V2P (not in VMM) of the server.

Notes:

• FAT/FAT32 cannot be converted using Online P2V
• You can do a P2V of virtual machines, however VMware users will want to use the V2V approach.
• You cannot do a P2V of an in-place cluster.  However you can convert each cluster node and then create a new failover cluster.