Windows Filenames & File/Directory Sizes

Do long filenames and/or large directories slow down a computer's performance?
In one word, C:\X123_ades11_4_dfag1_1345_122\X123_ax15_1343(p012)_wa1234_x6tc123a234_c112_x23_y11.YES!

In the Days-of-Olde, Microsoft had a neat little convention of 8.3.  Eight character filename prefix and 3 character suffix (extension).  As the operating systems grew, so did the filename lengths.  Microsoft has since given us more than enough flexibility to really screw ourselves up.

When saving a file with a long filename to an NTFS (New Technology File System) drive, NTFS creates a secondary file entry with a shorter filename conforming to the 8.3 convention.  The reason for this to allow older operating systems which cannot handle the larger names to index the file.  When NTFS enumerates files in a directory, it has to look up the 8.3 names associated with the long file names.  And because an NTFS directory is maintained in a sorted state, corresponding long filenames and 8.3 names are generally not next to one another in the directory listing. So, NTFS uses a linear search of the directory for every file in the volume. As a result, the amount of time required to perform a directory listing increases as a function of Square-Law.  Keeping in mind, this is in addition to the slow indexing due to the long filenames.

If you must use long filenames it would be beneficial disabling the 8.3 file creation.  Two registry keys will need to be changed: NtfsDisable8dot3NameCreation and NtfsDisableLastAccessUpdate  Set their values to 1.  Keep in mind, doing so may prevent longer filenames from working with older computers.

Performance Test is a program I put together to test the performance of the computers using either long files and/or lots of files and directories.  Basically it just creates a bunch of zero length files & directories and spits out the number of Operations Per Second (OPS).  FOPS being Files Operations Per Second and DOPS for Directory Operations Per Second.  Each experiment was done twice; one set with 36 character names, and the other with 144 character names.

  It is easy to see the difference between long and short file names.  The long file names seems to slow down the operation down about 30 -40%.  Keeping in mind, this is on a PC.  It will almost definitely be slower over a Network.  What is also interesting is how the OPS seems to take a hit around the 200 -500 file/directory mark.  I have seen this mentioned before in other articles but no one mentions why.  If I find some time I will look into it further.

So for my buddy Mike, here ya go, proof positive!

NTFS vs FAT vs exFAT