Hey everyone, after posting another question here, it seems I have to create a fixed disk in order to get one 700GB.

I have shut down the machine (which basically has nothing on it), and gone to convert to a fixed disk. It is going EXTREMELY slow - if my calculations are correct at the rate its going it will take ~2 days to complete. Its been going for about 6 hours and its about 10% complete. I'd like to continue setting up my server and start using all of the space.

Is this normal? How can I speed this up???

Thank you,

2 Answers 2


By default, when you create a VHD, the creation process zeros out the data as it builds the file.

MS released a tool to create VHD's very quickly which bypasses the zero out process.


To create a 100 GB VHD, use something like:

.\VhdTool.exe /create '.\Virtual Hard Disks\SRV-EXCHANGE_Backup.vhd' 107374182400

It will take only seconds to complete.


PS C:\VMStorage> .\VhdTool.exe /create '.\Virtual Hard Disks\SRV-EXCHANGE_Backup.vhd' 107374182400
        Status: Creating new fixed format VHD with name ".\Virtual Hard Disks\SRV-EXCHANGE_Backup.vhd"
        Status: Attempting to create file ".\Virtual Hard Disks\SRV-EXCHANGE_Backup.vhd"
        Status: Created file ".\Virtual Hard Disks\SRV-EXCHANGE_Backup.vhd"
        Status: Set the file length
        Status: Set the valid data length
        Status: VHD footer generated
        Status: VHD footer written to file.
        Status: VHD header area cleared.
        Status: Complete
PS C:\VMStorage>
  • To add to Andy's response, the blog entry Why does it take so long to create a fixed size virtual hard disk? by the Virtual PC Guy, provides some background explanation as to why it takes so long to create a fixed VHD. The reason why this takes so long is that when we create a new fixed-size virtual hard disk we take the time to explicitly zero-out all of the disk space that is being assigned to the new file.
    – Reuben
    Sep 7, 2009 at 5:54

If you are looking for a fast VHDX creation tool consider the Systola VhdxTool: It works almost like VHDTool but for VHDX and even offers compatible command line.

  • Why minus this? VHDTool is no longer available; this is a vaild answer.
    – namezero
    Jun 17, 2018 at 9:58

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