Jul
29

How To: Hot Extend Virtual Disks Using ESX 3.5 Update 2

Paul Shannon ESX, VMware, VirtualCenter, Virtualisation 2008-07-29

One of the great new bits of functionality in ESX 3.5 Update is the ability to hot extend non-boot virtual disks without shutting down the VM.

I decided to give it a go with a Windows 2003 Standard VM and thought I”d provide a How To for anyone that might need/want it.

You can download the pdf here.

It is the first version of the document so please feel free to comment and let me know how to improve it.

I”m working on a Linux equivalent, but to be honest, I have never tried this before in Linux so it might be a while until the Tech Note appears ;-)

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Address: http://www.vm-aware.com/2008/07/how-to-hot-extend-virtual-disks-using-esx-35-update-2/
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6 comments untill now

  1. VMware: Hot Extend Virtual Disks Using ESX 3.5 Update 2 « ICT-Freak @ 2008-07-30 07:09

    [...] pdf kun je hier downloaden: how-to-hot-extend-virtual-disks-using-esx-35-update-2 « VMware: ESX 3.5 and VC 2.5 update 2 [...]

  2. Virtualization Short Take #15 - blog.scottlowe.org - The weblog of an IT pro specializing in virtualization, storage, and servers @ 2008-07-31 21:27

    [...] Shannon at VM-Aware has a PDF on how to hot extend virtual disks with Update 2. I personally had a problem reading the PDF; the pictures were there but there was no text. Even [...]

  3. Rick Scherer @ 2008-09-07 18:19

    This functionality has always been in ESX, from the CLI you can grow a VMDK then use partition managers to extend the partition. It can even be done with boot volumes, simply mount the VMDK as a second disk on another VM.

    ie: vmkfstools -X ##

  4. Paul Shannon @ 2008-09-08 22:37

    Hi Rick

    You are right that the functionality of extending VMDK files has always been ESX for a long time and that a helper VM can even do a boot vmdk, but the point of the article was more to show point out the hot extend functionality.

    This functionality was introduced with ESX 3.5 Update 2 and admittedly builds on existing functionality, but now allows this functionality to work whilst the VM is running.

    Thanks for you comment

  5. Extending Boot Partitions | VM-Aware @ 2008-11-10 22:36

    [...] more disks in the physical world or by extending the vmdk size in the virtual world (see this article for more information) it is a case of a single line in the command prompt.

  6. Bruce Thompson @ 2008-12-03 20:15

    Hi Paul,

    We have a Linux environment on ESX 3.5 u2 so have been very keen to find a way to use the Hot Extend feature. I’ve been searching the net for a while for a method but found nothing so yesterday I asked a VMware guru about doing this with Linux. He gave me the following response:

    “I don’t know exactly what feature set we have in 3.5, especially in the
    storage area. However, I would imagine extending disks requires
    re-attaching to the storage layer in Linux, which means at least an
    unmount and re-mount. Typically, Linux won’t reprobe LUNs unless you
    remove the driver module and re-install, so you would need a root FS on
    a different storage type (Buslogic or IDE), and LSI Logic as a kernel
    module.

    Since dropping your entire non-root storage offline will take out any
    active processes working on that (they must be stopped, or you can’t
    unmount, and thus can’t remove the module), I would imagine this
    hot-extend feature is not much better than a reboot, certainly not as
    useful as PCI hot add/remove, which I believe we are adding in our
    upcoming 4.0 release. With PCI hot add, a new controller can be
    hotplugged, which truly allows you to add storage on demand with zero
    downtime. I don’t know if you can add LUNs on demand, it would be a
    driver dependent issue”.

    So I think that gives me closure on the possibility… it’s just not going to
    happen with Linux, at least for the moment.

    Cheers,
    Bruce

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