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Microsoft KB Archive/106266

From BetaArchive Wiki

Article ID: 106266

Article Last Modified on 9/22/1999


  • Microsoft Windows for Workgroups 3.11

This article was previously published under Q106266

kbtool kbtshoot kbfile


Your system seems slower after you enable 32-bit file access.


Enabling 32-bit file access can result in slower system performance in the following situations:

  • VFAT is unable to mount.

This can happen as a result of one or more of the following problems (note that the numbers below correspond to the numbered steps in the "VFAT is Unable to Mount" subsection of this article):

    1. The real-mode network redirector has been loaded into memory.
    2. A memory-resident program or device driver has a file open while Windows loads.
    3. The drive is involved in a SUBST, ASSIGN, or JOIN action. Because of the way they alter apparent disk characteristics, the SUBST.EXE, ASSIGN.COM, and JOIN.EXE programs are not compatible with installable file systems (IFS), such as 32-bit file access. These utilities can't be used if 32-bit file access is enabled.
    4. The cache size selected is too large or invalid.
    5. Required components are missing, corrupted, or not in the specified directory.
  • Windows for Workgroups version 3.11 is in a low-memory situation after enabling VFAT.

Running VFAT/VCACHE with SMARTDrive may place Windows for Workgroups into a low-memory situation because memory used by SMARTDrive is not available to VCACHE.386 and vice-versa. Since VCACHE.386 provides the caching on VFAT-enabled drives and network drives, while SMARTDrive caches CD-ROM drives and floppy disk drives, it is possible that systems with too large a percentage of memory allocated to caching have some performance reduction.


Low-Memory Situation

If you are in a low-memory situation (that is, you are running both SMARTDrive and VFAT), make sure that the amount of memory allocated to SMARTDrive's WinCacheSize and the cache size allocated to VCACHE.386 do not exceed roughly 30 percent of total system RAM.

For example, on a machine with 4 megabytes (MB) RAM, if you have allocated 1024 kilobytes (K) to VCACHE, set the SMARTDrive WinCacheSize to 128K. To do this, use a command similar to the following

c:\windows\smartdrv.exe <1024> <128>

where <1024> is the InitCacheSize (the cache size at MS-DOS) and <128> is the size of the cache in Windows.

VFAT Is Unable to Mount

If VFAT is unable to mount, try the following:

  1. You can unload the real-mode network redirector by typing net stop at the MS-DOS command prompt before starting Windows for Workgroups.
  2. To ensure that no device driver or terminate-and-stay-resident (TSR) program has any files open upon entering Windows for Workgroups, clean start the machine.

    For more information on clean start configurations for Windows for Workgroups version 3.11, query on the following words in the Microsoft Knowledge Base:

    wfw and clean and start

  3. Do not use the SUBST, ASSIGN, or JOIN utilities with 32-bit file access enabled. If you must use one of these utilities, disable 32-bit access first.
  4. Verify that the cache size selected is valid. For more information, see the "Low-Memory Situation" section above.
  5. The components used by VFAT vary depending on the system's hard disk drive (HD) controller type and whether or not disk compression (such as DoubleSpace, DriveSpace, or Stac Electronics Stacker) is used. If you suspect the components are missing, corrupted, or not in the specified directory, verify the components files sizes, or re-expand them from your original Windows for Workgroups version 3.11 disks.

       File              Size
       ----              ----
       IOS.386           28,352
       RMM.D32           11,894
       RMM.D32           11,473  (updated version of RMM.D32)
       VCACHE.386         9,862
       VFAT.386          32,925
       VXDLDR.386         5,678

    NOTE: VFAT cannot load on a volume compressed with MS-DOS 6.0 DoubleSpace. This problem was resolved in MS-DOS 6.2 and later.

    IMPORTANT: The SYSTEM.INI file entries shown in the examples below are made by Control Panel and do not require manual editing. These examples are provided to show the component files involved and to aid in troubleshooting. You should avoid manually editing your SYSTEM.INI file.

    Example 1: Uncompressed WD 1003 Compatible Drive

    Western Digital 1003 or ST506 compatible drives without compression require the following entries in the [386Enh] section of the SYSTEM.INI file:


    All entries marked with an asterisk (*) are contained in the WIN386.EXE file. All files should be located in your Windows SYSTEM subdirectory unless otherwise noted.

    Example 2: Compressed or Not WD 1003-Compatible Drive

    If the drive is compressed, or if another hard disk in the machine is not WD 1003 compatible, then the line "device=*BLOCKDEV" should be replaced with the following:


    In addition, the real mode mapper (RMM.D32) must exist in the Windows SYSTEM subdirectory.

    Example 3: Not WD 1003-Compatible Drive

    If 32-bit disk access cannot be used by a particular hard disk controller (because it is not WD 1003 compatible), the VFAT entries for the SYSTEM.INI file's [386Enh] section should include the following:


    Again, RMM.D32 must exist in the Windows SYSTEM directory.


VFAT is a 32-bit virtual MS-DOS file allocation table (FAT) file system and can only mount on hard disk volumes. If 32-bit disk access drivers are not available for a particular hard disk controller, additional handling of INT 13h calls is required. The IOS.386, VXDLDR.386, and RMM.D32 files provide this functionality and allow VFAT/VCACHE to work on these drives. (Drives affected include most SCSI and ESDI drives, a few IDE drives, and compressed volumes residing on any type of hard disk.)

32-bit disk access drivers may also be provided by an original equipment manufacturer (OEM) to work with a specific hard disk controller, replacing Microsoft's *WDCTRL. As a troubleshooting step, these drivers should be temporarily disabled and IOS.386, VXDLDR.386, and RMM.D32 should be used instead.

Additional query words: dblspace wfw wfwg 3.11 fastdisk slow slower slows tshoot

Keywords: KB106266