An oddity that's a little bit scary...

[mathewsdw]

As I usually do an unmodified partial log of a TCC session:

 Directory of  X:\Obsolete Music Files\z*

 7/20/2014  1:30  0  zia10224
  0 bytes in 1 file and 0 dirs
 1,407,083,044,864 bytes free

[X:\Obsolete Music Files]del zia10224
Deleting X:\Obsolete Music Files\zia10224
  1 file deleted  1,182,859,264 bytes freed

Presumably the question is obvious. How can deleting a file whose length is zero free 1,182,859,264 bytes bytes (more than a gigabyte!)?

 

[thedave]

If I recall correctly, it doesn't actually keep track of the space freed, but rather, it does a comparison against the free space at the start and end of the operation. This leaves plenty of room for oddities.

 

[rconn]

You've got something else running in the background. As Dave said, DEL does a "before and after" comparison. Your disk space might go down, stay the same, or even go up.

 

[mfarah]

Quick question: should the "before and after" behavior be the proper one (... at least for single file deletion)? After all, it's not like the system can't tell exactly how many sectors a certain file occupied.

 

[rconn]

Quick question: should the "before and after" behavior be the proper one (... at least for single file deletion)? After all, it's not like the system can't tell exactly how many sectors a certain file occupied.

TCC used to do that -- and I got hundreds of complaints from people who said that DEL told them they freed memory when they didn't (because Windows was deleting to the recycle bin or similar third-party app). The current solution was deemed the least confusing and apt to generate "bug" reports.

 

[mathewsdw]

Thank you guys and I believe you. But it is a little bit strange that something of that magnitude can happen in the time it takes to do a delete of a single zero-length file!

 

[rconn]

Thank you guys and I believe you. But it is a little bit strange that something of that magnitude can happen in the time it takes to do a delete of a single zero-length file!

Not really -- there's usually an enormous amount of activity going on in the background. Text indexing, incremental backups, temp file cleanups, disk optimization, journaling, etc.