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From: winders@aux.support.apple.com (Scott Winders)
Newsgroups: comp.sys.mac.system
Subject: Re: Is there a limit on the number of files?
Message-ID: <52820@apple.Apple.COM>
Date: 13 May 91 20:46:26 GMT
References: <76189@eerie.acsu.Buffalo.EDU>
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Organization: Apple Computer, Inc.
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In article <76189@eerie.acsu.Buffalo.EDU> v109lptc@ubvmsd.cc.buffalo.edu 
(Mark R Waldmiller) writes:

> Actually there is a limit.  It arises because the desktop file for 
> the Finder has its information stored as resources, and there is a 
> limit to the number of resources any given file can contain without
> the system crashing.  The limit on the number of resources is given
> in one of Apple's tech notes, I can't remember the exact value but
> it is approximately 2700. Since every file on your disk has a few 
> resources the finder uses (such as its icon, size information, and
> other such stuff), the actual number of files you can have on a
> given volume is about 700 or so.

Mark, 700 or so is certainly not the limit to the number of files on a
HFS volume. I have had volumes with 30,000 files on it (yes, desktop
updating was very slow due to the limitations of the Resource Manager 
as a database engine). 

Your concept of how the Desktop file in System 6.0.x and  earlier is a 
little flawed as well. Each file does not have an entry in the Desktop 
file that takes up a resource. Here is the text from Macintosh Technical
#210:

-----
There is a limit to the number of applications/files that the Finder can
"see" on a single volume. This limitation is imposed by the Desktop file.
The Desktop file is a resource file that the Finder uses to keep track of information about files and applications, including Finder file comments
(Get Info comments), and how these files and applications relate to each other. 

Because the Desktop file is a resource file, the maximum number of
resources it may contain is currently 2727 (refer to Technical Note #141).
To illustrate this limitation of the Desktop file, here are some example applications and how their entries currently affect the Desktop file.

-	The Finder puts a single resource into the Desktop file (the Finder is
  not on the disk).
-	MacWrite puts 10 resources into the Desktop file.
-	MacPaint puts 9 resources into the Desktop file.
-	MacDraw puts 8 resources into the Desktop file.
-	MacWrite and MacPaint together put 20 resources into the Desktop file.
-	MacWrite and MacDraw together put 19 resources into the Desktop file.
-	A generic application (no BNDL resource) or a file without any Finder
  file comments does not put any resources into the Desktop file.
-	Finder file comments put a single resource into the Desktop file.

Note: 	Both the maximum number of resources in a file, including the
Desktop file, as well as the number of resources the above examples
put into the Desktop file could change in the future.

As you can see, it is difficult to accurately predict how many applications/files will fit on any single volume.  Clearly, the more information an application or file carries with it, the larger its 
"entry" in the Desktop file.  This is normally not a problem, but with
the advent of very large capacity media, it is possible to reach this limitation by creating a single volume with too many applications/files.
-----

Scott Winders
internet: winders@aux.support.apple.com
AppleLink: winders.s@applelink.apple.com