Migrating Virtual Machines

I decided to use VMWare Update Manager to help upgrade the virtual machines like this:

  1. In the Update Manager VM View I created a baseline group that contained both VMWare tools upgrade and the VM Hardware upgrade baselines
  2. In the VMs and Templates I selected the Datacenter and in the Update Manager tab I Scanned for VM Hardware and Tools upgrades to check that nothing is needed before we move the VMs
  3. I shut down the VMs en masse (not too many at a time so that we don’t overwork the host and storage)
  4. When they are down I migrate them to the new cluster (I chose this approache so that I don’t enable Enhanced VMotion Compatibility as all new servers will run with Nehalem CPUs) and power them on
  5. After I waited for them to up properly I scanned again for VM updates in the datacenter tab (this was needed because the VMs are scattered around in a quite elaborate folder structure)
  6. I then clicked Remediate and checked that only the right VMs are in the list to be upgraded and finished the wizard without creating a snapshot (no need to snapshot VM Tools upgrade)
  7. After the task finished I let everything settle down a few minutes and then:
    1. Connected on all Windows 2008 machines to make online the offline disks (see http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1013109 ). I did this manuall because we had only a few Win 2008 Ent machines
    2. Rebooted all the Virtual Machines once more (after the VM Hardware upgrade Windows redetects devices and asks for a reboot; dynamic DNS records are also not registered properly)

So now I have a new beautiful working virtual infrastructure, yuppiee!

The performance benefit of this upgrade is beyond expectations, CPU Ready% got to almost 0 and CPU Usage went to almost half on the most used machines – see the following graphs for 4 various Virtual Machines running SQL, an Oracle Monitoring app or System Center Configuration Manager:

There was a downside to all this though :( : due to EPT features in Nehalem I get much less Transparent Page Sharing and thus much more memory usage – see http://www.vmware.com/files/pdf/large_pg_performance.pdf . I probably will disable the allocation of large pages to guests on some hosts that run less important VMs.

In conclusion I like vSphere a lot, the upgrade to 4.0 was MUCH easier than the upgrade to 3.0, thank you VMWare for this fine product! Storage VMotion rules, it’s so easy now to move VMs around datastores!

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