VMware vSphere

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  • 1.  clone vs template

    Posted Nov 26, 2009 05:20 PM

    Hi all, I'm reading the Sysadmin Guide. I don't understand the difference between clone and template.

    Seems very similar but the doc says as if it's different thing.

    What's the difference and can pls give example on when to use clone, when to use template.

    Thank you.



  • 2.  RE: clone vs template
    Best Answer

    Posted Nov 26, 2009 05:37 PM

    Clone is a copy of a VM (also running) with or without customization.

    Template is a VM that you cannot power-on (unless you convert to a VM). A deploy from template is just a "clone" of a template and the conversion in a VM.

    So are quite similar, the big difference is that template cannot be powered on.

    And can be stored in compact format (but now also VM can be in thin format).

    Andre



  • 3.  RE: clone vs template

    Posted Nov 26, 2009 05:57 PM

    Interesting differences! Thanks Andre.



  • 4.  RE: clone vs template

    Posted Nov 26, 2009 06:03 PM

    As Andre said, clones and templates are practically the same thing, but there are a few other differences. A VM template can support the provisioning of multiple VMs simultaneously. In other words, each "deployment" task will run concurrently in parallel. You can queue up multiple cloning operations, but the actual copy operation will only run one VM at a time. Another difference...vSphere now supports linked clones, which is a space-efficient copy of a VM. Within a linked-clone group, each clone is created almost instantly...sharing a snapshot of the source VM. The only additional space consumed would be disk writes that are unique to the clone. This feature is used heavily with VMware View when working with Automated Desktop Pools, and is available via VMware's APIs. The last functional different I can think of is that with a template you can have the image "prepped" and "sealed" via whatever means. It's meant for one purpose...to create new VMs from it...so you can sysprep, have scripts ready to run on 1st login, have an application configured in a default state waiting to be configured for the 1st time, etc. With a clone, things are usually already setup. While you can use vCenter's guest customization to do some basic things, templates tend to be more flexible for provisioning VMs from a "packaged" unit.



  • 5.  RE: clone vs template

    Posted Nov 26, 2009 06:23 PM

    Thanks so much enDemand.

    Btw, I read that we must install sysprep tool on the VCenter host. So, I try to install sysprep for w2k3 on my VC host (XP), but it forbid me, say the sysprep is for the wrong OS. I don't get it. Does it mean I have to have many VC on each different OS if I want to use sysprep?



  • 6.  RE: clone vs template

    Posted Nov 26, 2009 06:30 PM