Path: utzoo!attcan!uunet!husc6!ukma!rutgers!mcdchg!chinet!ward
From: ward@chinet.chi.il.us (Ward Christensen)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Large number of files slows machine.
Message-ID: <7255@chinet.chi.il.us>
Date: 23 Dec 88 05:06:48 GMT
References: <8545@j.cc.purdue.edu> <7192@chinet.chi.il.us> <1078@pilchuck.Data-IO.COM>
Reply-To: ward@chinet.chi.il.us (Ward Christensen)
Organization: Chinet - Public Access Unix
Lines: 28

In article <1078@pilchuck.Data-IO.COM> del@pilchuck.Data-IO.COM 
  (Erik Lindberg) writes about... (attributions getting too lengthy,
  Pruned)
  The original article wondered why a disk with >650 files/subdir was slow
doing DIR and other things.
  I stated:
>>  What is happening is the fragmentation of your directory resulting in
>>many seeks while processing the directory.
   while Erik stated "This might SEEM to be what is happening on your 
system, but it isn't right", and said that in a case where his directories
completely fit in cache (eliminating seek time), he found "a massive 
increase in file access time when the number of files in a subdirectory 
exceeds 512."
  To defend my initial comment (but not say Erik is wrong the way he said I
was): my Compuserve capture directory slowed WAY down at one time, and I 
finally traced it.  Deleting files from the directory didn't help, so I 
looked - and found my directory in 3 extents "all across the disk" (say, 
at 1/4, 1/2, and 3/4 the way across).
  By copying the files in the 3rd extent to a temp directory, then
manually patching the FAT to not point to the 3rd extent, then copying the
file back - so I had the SAME NUMBER of files but in 2 extents instead of
3, the speed improvement was very significant.
  So, Erik in MY case, the NUMBER OF DIRECTORY EXTENTS was VERY significant
- probably due to the slow seek time.  In YOUR case it was the sheer number
of files.  We're both right - like a car that can mis-fire from either fuel
or electrical problems, a hard disk can slow down from either too many
files or too many directory extents (and probably more things).
  Happy Holly-Daze to you all.