How to make a file of an size fast - fsutil file createnew test 1048576

https://stackoverflow.com/questions/982659/quickly-create-large-file-on-a-windows-system

http://technet.microsoft.com/en-us/sysinternals/bb897428.aspx

Quickly create large file on a Windows system

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In the same vein as Quickly create a large file on a Linux system, I'd like to quickly create a large file on a Windows system. By large I'm thinking 5 GB. The content doesn't matter. A built-in command or short batch file would be preferable, but I'll accept an application if there are no other easy ways.

• windows
• batch-file

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edited Sep 8, 2018 at 20:57

Peter Mortensen

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asked Jun 11, 2009 at 18:01

Leigh Riffel

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fsutil file createnew <filename> <length>

where <length> is in bytes.

For example, to create a 1MB (Windows MB or MiB) file named 'test', this code can be used.

fsutil file createnew test 1048576

fsutil requires administrative privileges though.

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edited Feb 14, 2021 at 12:43

DxTx

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answered Jun 12, 2009 at 10:37

Patrick Cuff

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  @ZXX +1 For my purposes I merely needed the file system to see the space as unavailable, but your information is helpful if someone else needs this. 

  – Leigh Riffel

   Dec 22, 2010 at 13:50
• 24
  fsutil file createnew does not create a sparse file. 

  – Per Mildner

   Jun 30, 2013 at 17:58
• 10
  "fsutil sparse setflag temp.txt" sets the sparse flag, making it a sparse file. "fsutil sparse setrange temp.txt 0 1024" sets the range of sparseness :) 

  – Coldblackice

   May 10, 2014 at 21:53
• 3
  @ZXX fsutil file createnew does NOT create sparse files: c:\>fsutil file createnew test.txt 0x100000 File c:\test.txt is created c:\>fsutil sparse queryflag test.txt This file is NOT set as sparse 

  – ivan_pozdeev

   Oct 20, 2017 at 6:29 
• 4
  This might not technically be a sparse file, but creating a 500GB file takes less than a second (even on a somewhat faulty hard disk). If you want to actually trigger 500GB of disk IO (like I do), this command isn't it. 

  – Simon Kissane

   Oct 5, 2018 at 7:43 

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You can use the Sysinternals Contig tool. It has a -n switch which creates a new file of a given size. Unlike fsutil, it doesn't require administrative privileges.

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edited Jan 7, 2018 at 10:42

answered Jun 11, 2009 at 19:1