Virtualization Pro

Mar 11 2008   7:13PM GMT

The Clone Wars

Scott Lowe Profile: Slowe

I started to call this post “Attack of the Clones”, but I was a bit worried that George Lucas might get upset at my use of his movie title. So, while sticking to the Star Wars theme, I settled on the current title.

The idea of leveraging the cloning functionality that’s present in many storage arrays on the market today is not a new or unusual one. In particular, on my personal blog I wrote a number of articles about the processes around using clones, the advantages of using clones, and some of the disadvantages of using clones. While my articles were primarily focused around storage systems from Network Appliance (now just NetApp), the basic principles are very similar for other storage arrays as well.

In How to Provision VMs Using NetApp FlexClones, I discussed the processes and procedures around the use of hardware-based clones. In particular, new functionality within ESX Server 3.x required administrators to enable resignaturing in order to see cloned VMFS datastores and be able to use the virtual machines stored in those datastores. At the time, there was no automated way of registering the VMs stored in the cloned datastores as well, and I believe that is still true even today.

Having discussed the “how” of using clones, I moved on to a couple of articles discussing the advantages and disadvantages of using storage system clones. In NetApp FlexClones with VMware, Part I, I presented the advantages of using clones:

  • Reduced storage usage
  • Reduced time to create VMs

In NetApp FlexClones with VMware, Part 2, I moved on to some of the disadvantages of using storage system-based clones:

  • Scalability issues with regards to a maximum number of LUNs supported within VirtualCenter
  • Lack of integration with VMware’s graphical tools
  • Potential blurring of responsibilities across functional IT teams

Clearly, it’s up to each customer to determine whether the advantages and disadvantages are truly applicable to their organization. For some organizations, the “potential blurring of responsibilities” may be a non-issue, and the reduced storage requirements are a major issue.

Of course, it’s also possible to use hardware-based clones for purposes other than just provisioning. In VM File-Level Recovery with NetApp Snapshots and Full VM Recovery with NetApp Snapshots, I discussed ways to leverage NetApp FlexClones and LUN clones–which are based on Snapshots–to facilitate VM recovery scenarios. So this technology can be used for a variety of purposes in VMware environments.

If you’re a reader whose using hardware-based clones or snapshots — not necessarily Network Appliance-based, but from any hardware vendor — are you using this functionality? How are you leveraging it in your environment? I’d love to hear about the ways in which you are putting these kinds of technologies to work in the real world.

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