Javy de Koning

Welcome

Geek 🤓, love sports 🏃‍♂️🏋️‍♂️, food 🍛,
tech , @ Amsterdam ❌❌❌.

Javy de Koning

3 minutes read

Get-ChildItem is probably the command that’s most used when working in PowerShell console. Next to file-system operations the command is also excellent to browse objects accessible via PSDrive(s).

Most sysadmin’s are probably familiar with tools such as TreeSize and/or WinDirStat. Did you ever wonder why these tools are so much faster than Get-ChildItem? There is even a PowerShell TreeSize implementation available on the PSGallery, however it’s pretty slow when running on large file-servers.

The downside of Get-ChildItem is that it will not let you grab a sub-set of properties. It seems likely that this is one of the reasons Get-ChildItem is slow.

The following 3 commands will all produce the same result, which is the total Dir Size in bytes:

#Use erroraction silentlycontinue to ignore access denied errors 
(`Get-ChildItem` $home -Recurse -force -erroraction SilentlyContinue | Measure-Object length -Sum).sum 

#Good old Dir, recursively
((cmd /c dir $home /-C /S /A:-D-L)[-2] -split '\s+')[3]

#RoboCopy in list only mode: 
(robocopy.exe $home c:\fakepathduh /L /XJ /R:0 /W:1 /NP /E /BYTES /NFL /NDL /NJH /MT:64)[-4] -replace '\D+(\d+).*','$1'

17996994274
17996994274
17995815085

Dir size in Windows Explorer

All commands come close enough with only a 1MB deviation in the RoboCopy.exe version. On the right-hand-side you will find a screenshot showing the properties of my homefolder. This also shows a small deviation. This deviation seems to be the result of a growing VHD file in my homefolder. I’ll list to RoboCopy parameters for reference

  • /L : List only
  • /XJ : Do not follow NTFS junctions
  • /R:0 : Retries 0
  • /W:1 : Wait 1 sec before retry
  • /NP : Don’t display progress
  • /E : Include empty folders
  • /BYTES : Display output in bytes (not supported on pre Win7 RoboCopy versions)
  • /NFL /NDL : No file and No directory listing
  • /MT:64 : Use 64 threads

Measuring the Dir Size calculations

So how fast are these commands actually? Which command should we use? Let’s use Measure-Command to find out:


There you go Dir.exe is 3.79x faster than Get-ChildItem on my notebook with SSD. RoboCopy.exe is 18.86x faster.

Warning BUGS

I found a bug when using DIR over PowerShell Remoting. After some fiddling around it appears as DIR get’s into an infinite loop when recursively listing ‘C:\Users\Username\AppData\Local\Application Data'. When running in a local PowerShell session DIR will not try to follow the NTFS Junction. We’ve been able to reproduce this issue on Windows 2008, 2012R2 and on 2016TP5.

When executing locally:

cmd.exe /c dir /A:H
Volume in drive C has no label.
Volume Serial Number is E653-EF16

Directory of C:\Users\jdekoning\AppData\Local\Application Data

File Not Found

When executing over PSR:

cmd.exe /c dir /A:H
Volume in drive C has no label.
Volume Serial Number is E653-EF16

Directory of C:\Users\jdekoning\AppData\Local\Application Data

05/04/2016  10:47 AM    <JUNCTION>     Application Data [C:\Users\jdekoning\AppData\Local]
05/04/2016  10:47 AM    <JUNCTION>     History [C:\Users\jdekoning\AppData\Local\Microsoft\Windows\History]
05/19/2016  08:34 AM            23,699 IconCache.db
05/04/2016  10:47 AM    <JUNCTION>     Temporary Internet Files [C:\Users\jdekoning\AppData\Local\Microsoft\Windows\INetCache]
               1 File(s)         23,699 bytes
               3 Dir(s)  127,835,623,424 bytes free
comments powered by Disqus

Recent posts

See more

Categories

About

There should go some text here but I'm to lazy to write it.