SMARTDRV Cache Status -- What Does the Buffering Value Mean? (82709)

The information in this article applies to:
    Microsoft Windows 3.0
    Microsoft Windows 3.0a
    Microsoft Windows 3.1
    Microsoft Windows 3.11
    Microsoft Windows for Workgroups 3.1
    Microsoft Windows for Workgroups 3.11
    Microsoft MS-DOS operating system 6.0
    Microsoft MS-DOS operating system 6.2
    Microsoft MS-DOS operating system 6.21

This article was previously published under Q82709


In MS-DOS, Windows, and Windows for Workgroups, the character-mode display of the status of SMARTDrive has a column for buffering status. The entry in this column can be "yes," "no," or "-" (MINUS SIGN). This article describes the meaning of these entries.


The following is an example of the printout you receive if you access SMARTDrive from the command prompt by typing smartdrv and pressing the ENTER key:
   Microsoft SMARTDrive Disk Cache version 4.0
   Copyright 1991,1992 Microsoft Corp.

   Cache size: 1,048,576 bytes
   Cache size while running Windows: 1,048,576 bytes

               Disk Caching Status
   drive   read cache   write cache   buffering
     A:       yes           no           no
     B:       yes           no           no
     C:       yes           yes          yes
     F:       yes           yes          -
     G:       yes           no           no

   For help, type "Smartdrv /?"
The column labeled "buffering" describes the state of double buffering. "Yes" in this column means that double buffering is being performed on the corresponding drive. "No" means that buffering is not being performed on the corresponding drive. The state indicated by a MINUS SIGN means that SMARTDRV.EXE cannot determine if buffering is needed.

SMARTDRV.EXE watches each data transfer to determine the need for buffering. If it sees a transfer to an upper memory block (UMB), it may be unable to determine if there is a need for double buffering.

NOTE: The double buffer driver must be loaded for SMARTDRV.EXE to determine if there is a need for buffering. If the double buffer driver is not loaded, all entries in the buffering column read "no." The double buffer driver is loaded from the CONFIG.SYS file. The following is a sample line to install the double buffer driver:
Even if you install the double buffer driver, SMARTDRV.EXE may decide that it is not needed. In this case, the double buffer driver is not loaded and does not take up any memory.

You can force the double buffer driver to load even if SMARTDRV.EXE decides that it is unnecessary. Adding a PLUS SIGN (+), as in the following example, forces the double buffer to load:

Modification Type: Major Last Reviewed: 11/25/2003
Keywords: KB82709