Errors Creating Files or Folders in the Root Directory

• Microsoft Windows 95

SYMPTOMS

You may receive an error message when you create a file or folder in the root directory. The exact error message depends on the method used to create the file or folder.

Using the COPY command in an MS-DOS session reports the following:

   Cannot make directory entry - <filename>

   <filename>: This filename is not valid.

   Unable to create <"New Folder">. Make sure the disk is not full or
   read-only.

CAUSE

This problem occurs when all 512 root directory entries have been used. This problem can also occur with fewer than 512 files and folders in the root directory because Windows 95 uses additional directory entries to store long file names.

STATUS

To ensure compatibility with MS-DOS, Windows 95 uses a standard file allocation table (FAT) file system. The root directory for a FAT drive has a fixed size and is stored in a fixed location on the disk. All hard disk drives use 32 sectors of 512 bytes each to store the root directory. This limits the root directory on a hard disk drive to 16K: 32 sectors x 512 bytes per sector = 16,384 bytes, or 16K.

MS-DOS uses one directory entry for each file and folder, but Windows 95 uses additional directory entries to store long file names and folder names, and the associated 8.3 aliases. This means that you can run out of directory entries with fewer than 512 files or folders in the root directory.

Folders do not have a fixed size, so the only limitation to the number of files or folders you can store in any folder with Windows 95 is free disk space. For this reason, it is best to store your files (programs and data) in a folder off the root directory.

RESOLUTION

Use the following steps to free root directory entries:

1. Check the drive for invalid long file names, and then defragment the drive as follows:

   Use the right mouse button to click the drive icon in My Computer or Windows Explorer and the click Properties on the menu that appears. Click the Tools tab and then click Check Now. Perform the default correction if invalid long file names are found. Then choose Defragment Now.

2. Rename any files or folders in the root directory using only upper- case 8.3-compliant file or folder names.

   The characters that are valid for an 8.3-compliant file or folder name include any combination of letters (A-Z) and/or numbers (0-9), plus the following special characters:

         $   Dollar sign
         %   Percent sign
         '   Apostrophe
         `   Opening single quotation mark
         -   Hyphen
         @   At sign
         {   Left brace
         }   Right brace
         ~   Tilde
         !   Exclamation point
         #   Number sign
         (   Opening parenthesis
         )   Closing parenthesis
         &   Ampersand
         _   Underscore
         ^   Caret
   
   

3. Move some files or folders out of the root directory.

MORE INFORMATION

An MS-DOS FAT root directory contains a separate entry for every file and folder it contains. These directory entries contain information such as the file name, extension, attributes, time and date the file was last modified, the starting cluster number, and the file size. Each directory entry uses 32 bytes to store this information. Because the root directory is 16K in size, it can contain a maximum of 512 directory entries, which are 32 bytes each.

When you name a file or folder in Windows 95, the system creates a primary file name, which can be a long file name, and an MS-DOS-compliant 8.3 alias. If the file or folder name is already 8.3-compliant, only one directory entry is used.

NOTE: For a file or folder name to be 8.3-compliant, it must contain only those characters that are valid for an 8.3 alias name, and it must be composed of all uppercase characters.

Windows 95 allows file and folder names to contain up to 250 characters. Valid characters for a Windows 95 file name include all the valid MS-DOS file name characters, the space character, and the following additional characters:

   +   Plus sign
   ,   Comma
   .   Period
   =   Equal sign
   [   Opening bracket
   ]   Closing bracket

If the file name is not 8.3-compliant, Windows 95 automatically generates an 8.3 alias for the file name. An additional directory entry is used to store the 8.3 alias. If the primary file name contains more than 13 characters, an additional directory entry is used.

The following table shows some primary file names, their 8.3 aliases, and directory entry usage in Windows 95:

   Primary               Possible       Directory
   file name             8.3 alias      entries used
   -------------------------------------------------
   EXAMPLE.TXT           EXAMP~1.TXT         1
   Example.txt           EXAMP~1.TXT         2
   !@#$%&().{^}          !@#$%&~1.{^}        1
   !@#$%&().{+}          !@#$%&~1.{}         2
   LFN TEST.TXT          LFNTES~1.TXT        2
   This is a LFN.TEST    THISIS~1.TES        3
   This is a very long
    file name.test       THISIS~2.TES        4