TB & PB

PowerShell Team

“To ship is the choose.”  That is the sad reality behind a number of the things that we regretted about V1.  When we first started the project (a LONG time ago) we knew that we wanted to close the semantic gap between what admins thought and what they had to type.  Imagine that you wanted to find all the processes that had greater than 15MB of workingset.  Who the heck could type in the following:

PS>  Get-Process |where {$_.Workingset –ge ?????}

What?  You didn’t know that 15MB was 15728640 bytes?  Yes you should have written:

PS>  Get-Process |where {$_.Workingset –ge 1572850}

Wait – is that right? 

NO!  As I typed it in, I made a mistake.  I thought I would leave it in to make the point.  If you came across this line in a script would  you have caught the mistake?  I doubt it.  Ok Ok – so  you’re a genius – I asked the question wrong.  Would the person in the next office have caught the mistake?  Right – “no way!”

That is why we added shortcuts KB, MB, and GB

PS> 1kb
1024
PS> 1mb
1048576
PS> 1gb
1073741824
PS> 15mb
15728640
PS> 1kb+2mb+3gb
3223323648

This then allows you to type things like:

PS>  Get-Process |where {$_.Workingset –ge 15mb}

Sadly we did this so early on that we thought GB was going to be enough.  It wasn’t that long before we realized our mistake in not including TB and PB but at that point, we were up to our necks in feature prioritization and this never became higher priority than something else. 

With V2, we decided to remedy this situation and we now support TB and PB.

PS> 1tb
1099511627776
PS> 1pb
1125899906842624
PS> 1kb+2mb+3gb+4tb+5pb
5633900804047872

(Want to double check our math?  🙂 )

To me, the interesting part of this story is the way we got this into V2.  The fact of the matter is that if we had done feature prioritization, I doubt very much that we would have included this change.  What happened was that a number of us were embarrassed by this mistake and just decided to do the right thing and fix it.   In retrospect, I think it was exactly the right thing to do.  The lesson here is that you have processes and you have judgment and that success is all about finding the right balance between these two.

Experiment!  Enjoy!  Engage!

Jeffrey Snover [MSFT]
Distinguished Engineer
Visit the Windows PowerShell Team blog at:    http://blogs.msdn.com/PowerShell
Visit the Windows PowerShell ScriptCenter at:  http://www.microsoft.com/technet/scriptcenter/hubs/msh.mspx

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