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Backup to VHD wasted space

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  • Backup to VHD wasted space

    Hi everyone,

    Just want to give a bit of background so you understand the issue better. We're running Hyper-V Server 2008 with 3 Server 2008 VMs. We currently have them do weekly backups to external hard drives that are directly attached to the Hyper-V host machine. We dedicated an external drive to each VM by creating a VHD file for the VM to use as storage for the backup images.

    Now for the issue: over time, I noticed the backup volumes appear to be filling up rather quickly. I checked the folder sizes and there are considerable differences in what is shown to be used and what is actually being used. Example, our Exchange VM backup has a capacity of 394GB, the only thing on this volume are the backup images with a total of 139 GB, but it only shows a total of 86.9GB free. I SHOULD have 255 GB free, the difference being 168.1GB, what is utilizing the remainder of the storage space?

    My previous solution was the format the backup volume and start fresh which seemed to work for sometime but this keeps happening. I want to change from weekly to daily backups as well, I can't go reformatting every other week because storage space is being wasted. Any ideas?

  • #2
    Re: Backup to VHD wasted space



    • #3
      Re: Backup to VHD wasted space

      So the backups (as VHD files) are going to a VHD file on the external drive....
      IIRC VHDs do not ever give up space , so you might be easier creating 3 folder shares and backing up direct to them
      Tom Jones
      MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
      PhD, MSc, FIAP, MIITT
      IT Trainer / Consultant
      Ossian Ltd

      ** Remember to give credit where credit is due and leave reputation points where appropriate **


      • #4
        Re: Backup to VHD wasted space

        Definitely not snapshots, the only thing stored in that folder are Window Server backup files.

        The backups are VHD files created by the host machine onto external drives and mounted on the VM which is seen as an extra drive with its own volume label.

        So your proposal is to dismount the volumes from the VMs, reformat the external drives on the host machine, and create folder shares to have the backups send directly? Sounds like a pretty good bet to me!

        Any clue as to why this would happen with the VHDs?