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BUFFERS


Description | Syntax | Parameters | Switches | Related | Notes | Examples | Errorlevels | Availability

Allocates memory for a specified number of disk buffers when your system starts. You can use this command only in your CONFIG.SYS file.


Syntax

BUFFERS=n[,m] [/X]


Parameters
m (v2.0 NT3.5)
Specifies the number of buffers in the secondary buffer cache. The value of m must be in the range 0 through 8. Default is 2 (PC and XT), 3 (AT), 10 or 15 (512Kb RAM).
n (v2.0 NT3.5)
Specifies the number of disk buffers. The value of n must be in the range 1 through 99. Default is 1.

Switches
/X (v4.0 through (v5.0)
Allows up to 10,000 n buffers.

Related

none


Notes
Default Settings

The default setting for the number of disk buffers depends on the configuration of your system, as shown in the table:

        Configuration              Buffers      Bytes (n)
        <128K of RAM, 360K disk    2            none
        <128K of RAM, >360K disk   3            none
        128K to 255K of RAM        5            2672
        256K to 511K of RAM        10           5328
        512K to 640K of RAM        15           7984
        Configuration              Buffers      Bytes (n)

The default setting for the number of buffers in the secondary cache (m) is 0 (no secondary cache buffers).

If you specify an invalid value for n or m, BUFFERS uses the default setting of no secondary cache buffers.


Using BUFFERS with DriveSpace

If you are using SMARTDrive with DriveSpace and the operating system is loaded into the HMA, set BUFFERS=10. This ensures that there will be enough room in the HMA for the operating sytem, DriveSpace, and all your buffers. (If BUFFERS is set to a value higher than 10, there might not be enough room in the HMA for all your buffers, and the operating system will place all the buffers into conventional memory.) If you're using SMARTDrive, specifying more than 10 buffers will not speed up your system much, but will use additional memory.


Using BUFFERS with SMARTDRV.EXE

If you are using SMARTDRV.EXE, either use a smaller value for BUFFERS, or do not specify a BUFFERS command at all.


How MS-DOS uses buffers

The operating system uses the memory reserved for each disk buffer to hold data during read and write operations. To achieve the best performance with programs such as word processors, specify a value between 10 and 20 for n. If you plan to create many subdirectories, you might want to increase the number of buffers to 20 or 30. Each buffer requires approximately 532 bytes of memory. Therefore, the more buffers you have, the less memory you have available for programs. (To find out how much memory the operating system is using for disk buffers, use MEM /D /P.)

If the operating system is loaded in the high memory area (HMA) and there is enough room in the HMA to contain all the buffers, the operating system also places the buffers in the HMA. If you specify more than 48 buffers, or if you upgraded from MS-DOS 6.22, are running DriveSpace, and specify more than 10 buffers, there might not be enough room in the HMA for all the buffers. In that case, the operating system places all of the buffers into conventional memory.


Using the secondary buffer cache

Using the cache can speed up certain disk operations if you are using a computer with an 8086 processor. If you are using a computer with a faster processor, it is better to use SMARTDRV for a cache.


Examples

Create 20 disk buffers, include in your CONFIG.SYS file:

    buffers=20

Errorlevels

none.


Availability
Internal
DOS
v2.0 v2.01 v2.05 v2.10 v2.11 v2.11R v2.12 v2.2 v2.25 v3.0 v3.20 v3.05 v3.1 v3.21 v3.25 v3.30 v3.3A v3.3R v3.3T v3.31 v3.40 v4.0 v4.01 v4.01A v5.0 v5.0A v5.00.02 v5.001A v5.01 v5.02 v6.0 v6.10 v6.2 v6.21 v6.22 v6.23 v7.00 v7.0R1 v7.10 v8.00
Windows
none
Windows NT
NT3.5