Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!ut-emx!young
From: young@ut-emx.UUCP (Young)
Newsgroups: comp.os.msdos.misc
Subject: Re: Limit on number of files per directory
Message-ID: <34573@ut-emx.UUCP>
Date: 27 Jul 90 22:52:24 GMT
Reply-To: young@ut-emx.UUCP (Young U. Ryu)
Organization: UTexas Computation Center, Austin, Texas
Lines: 49

Limit on Number of Directory Entries
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

1. Each directory entry (usually file) requires
   32 bytes for sttributes and specifications.
   ^^^^^^^^
2. One sector usually provides 512 Kbytes.
                               ^^^^^^^^^^
3. Each disk type uses different number of sectors
   for directory entry information. High-density
   disks use _14 sectors_ (7168 bytes), double-sided
   double-density disks use _7 sectors_ (3584 bytes),
   and single-sided double-density disks use
   _4 sectors_ (2048 bytes), regardless the size
   of disk (e.g. 5.25" or 3.5").
   Note: In case of double-density 5.25" disks,
         both 9 and 8 sector formats use the same
         amount of sectors for directory entry
         information.

4. Now, one can easily :-) calculate the maximum number
   of directory entries:

   DSSD (160 or 180 Kbytes)    -  64 entries
   DSDD (320, 360, 720 Kbytes) - 112 entries
   DSHD (1.2 or 1.4 Mbytes)    - 224 entries.

5. As Mr. Glenn L. Austin @ Apple Comp. Inc.
   (austing@apple.com) posted on 7/26/90,
   most hard disks support(ed) up to 512 directory
   entires. But, under a DOS 4.xx, the number
   may be different. In addition, the number is
   dependent on the physical design of a hard disk.

6. Finally, let me quote Mr. Glenn L. Austin's words:

   > Don't forget that the Label uses one directory entry,
   > two are used for the low-level DOS (xxxIO, xxxDOS),
   > one is needed for CONFIG.SYS, one is needed for
   > COMMAND.COM (unless you specify otherwise in CONFIG.SYS),
   > and one is used for each subdirectory in the root directory.

   These are important things that are frequently overlooked.


Young @ the University of Texas at Austin

young@emx.utexas.edu (Arpa/Internet)
BGBG767@UTAIVC (Bitnet)