WMWare workstation – copying, snapshots, cloning

A lot of people these days use Virtual Machines for testing and development due to their flexibility and versatility.

I make heavy use of them to host demos and also to have an instance of various environments at hand. For example, i have a the following VMs:

  • Windows XP
  • Windows Server 2003/SQL 2005/Sharepoint 2007/PPS07
  • Windows Server 2003 R2/SQL 2008
  • Windows Server 2008 R2/SQL 2008R2/Sharepoint 2010
  • Windows Server 2008R2/Denali

Sometime when building an image i like to keep a complete “snapshot” backed up at various points so i can revert to it if need be. I also want to use the “snapshot” as a base for future work. For example, once i have Windows server 2008 R2 installed i could store that away so that next time i have this ready to go to build a different VM.

I say “snapshot” in quotes here because i did not use the Snapshot feauture of VMware workstation. This lets you keep a single physical copy of a VM with snapshots stored as part of the whole VM defnition. Note many native VMware snapshots on a VM can degrade performance over time due to the differential nature of the storage after snapshotting. Anyway, I specifically want a separate image that i can pick up and at any time and work with independently.

So, in order to satisfy my requirement i would simply copy my VM folder to a backup location after each signficiant point of development. All good? Not really! One day i had some corruption in a VM and needed to revert to a previous copy. I booted it up only to find it was behaving strangely and wasnt the copy i expected it to be. I thought somehow it had gotten corrupt/confused as well.

After a few days i looked at the VM settings and figured it out. When you copy a VM it still points to the virtual hard disk at the original locations! So my pristine backup was botting off the corrupted virtual disk! There are two ways out of this.

  1. Reconfigure the backup VM to point to the virtual hard drive in its own folder
  2. The preferred method – to avoid this situation in the first place – dont simply copy the VM to back it up. Use the Clone option in Workstation and it will make a proper independent copy. You can also use this to rename a Virtual Machine safely.

This may seem like a trivial and newbie mistake – it probably is. But hey, if it took me years to run into this situation perhaps this info will hep someone else!

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