Can I compress a hyper v snapshot .avhd

Posted on 2012-08-19
Last Modified: 2013-12-02
I have a 3tb D: drive (SAS RAID array) storing a 2tb vhd of a VM.

I have a 3tb SATA drive (E:), which holds a ~600gb .avhd snapshot

I also have the most recent child .avhd snapshot fragment which is ~350gb running on the D drive.

I plan to manually merge the 350gb and 600gb fragments using this guide:

The problem is, my copy speed from the SATA drive is only 30MB/s. That means it'll take nearly all day to do the merge - and I only have a maintanance window of 10hrs to get this done - and I'll be left with no space on the D drive for additional growth of the fragments.

Array is full so can't add more disks.

Is it safe at all to run a compression on the base .vhd or any of the .avhd's?

Is there any other way I can compress them or reduce their footprint?
Question by:itGenius
    1 Comment
    LVL 20

    Accepted Solution

    You cannot run compress while there is a snapshot. A compress can be run on a VDH disk only.

    Also, in my humble opinion, doing manual merge could be quite risky and certainly it is not supported from Microsoft (witch means if something goes wrong you cannot call them for help).

    I will suggest another more safer approach:

    1. Build a temporary Hyper-v server with at least 6TB disk space (this could be made of 2 JBOD disks or an external iSCSI)
    2. Export the VM from the production server and import it in the temporary one.
    3. Complete the merge there
    4. Do not power on th vm on the temporary server
    5. Export the compressed VM and replace the original one by it: delete the the original vm and import the compressed one.

    This is much safer approach and in any stage you will have an uncompressed copy in case something goes wrong.

    The downside: I will take muh longer than 10 hrs so you'll hav to find a better window.

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