MS-DOS v6.22 Help: SMARTDRV

------------------------ MS-DOS v6.22 Help: SMARTDRV -------------------------
<Notes> <Examples>                                               <Index>
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                                  SMARTDRV

Starts or configures SMARTDrive, which creates a disk cache in extended
memory. A disk cache can significantly speed up MS-DOS disk operations. When
used for disk caching, SMARTDrive is loaded by using the SMARTDRV command in
your AUTOEXEC.BAT file or at the command prompt.

SMARTDrive can also perform double buffering, which provides compatibility
for hard-disk controllers that cannot work with memory provided by EMM386 or
Windows running in 386 enhanced mode. To use double buffering, load the
<SMARTDRV.EXE> device driver by using a DEVICE command in your CONFIG.SYS
file.

SMARTDrive will not load after Windows has started.

Syntax

When starting SMARTDrive from your AUTOEXEC.BAT file or from the command
prompt, use the following syntax:

    [drive:][path]SMARTDRV [/X] [[drive[+|-]]...] [/U] [/C|/R] [/F|/N] [/L]
    [/V|/Q|/S] [InitCacheSize[WinCacheSize]] [/E:ElementSize]
    [/B:BufferSize]

Once SMARTDrive is running, use the following syntax:

    SMARTDRV [/X] [[drive[+|-]]...] [/C|/R] [/F|/N] [/Q|/S]

To view the current status after SMARTDrive has loaded, use the following
syntax:

    SMARTDRV

Parameters

[drive:][path]
    Specifies the location of the SMARTDRV.EXE file.

[[drive+|-]
    Specifies the letter of the disk drive for which you want to control
    caching. Include the plus (+) sign to enable caching for the specified
    drive; include the minus (-) sign to disable caching for that drive. You
    can specify multiple disk drives.

    If you specify a drive letter without a plus or minus sign, read-caching
    is enabled and write-caching is disabled. If you specify a drive letter
    followed by a plus sign (+), read-caching and write-caching are enabled.
    If you specify a drive letter followed by a minus sign (-), both
    read-caching and write-caching are disabled. If you don't specify a
    drive letter, floppy disk drives, CD-ROM drives, and drives created
    using Interlnk are read-cached but not write-cached, hard disk drives
    are both read-cached and write-cached, and network drives and Microsoft
    Flash memory-card drives are ignored. (For information about how
    DriveSpace caches compressed drives, see Notes.)

InitCacheSize
    Specifies the size in kilobytes of the cache when SMARTDrive starts
    (when Windows is not running). The size of the disk cache affects how
    efficiently SMARTDrive runs. In general, the larger the cache, the less
    often SMARTDrive needs to read information from the disk, which speeds
    up your system's performance. If you do not specify an InitCacheSize
    value, SMARTDrive sets the value according to how much memory your
    system has (see the table below).

WinCacheSize
    Specifies, in kilobytes, how much SMARTDrive will reduce the cache size
    for Windows. When you start Windows, SMARTDrive reduces the size of the
    cache to recover memory for Windows' use. When you quit Windows, the
    cache returns to its normal size. WinCacheSize specifies the smallest
    size to which SMARTDrive will reduce the cache. The default value
    depends on how much available memory your system has (see the table
    below). If you specify a value for InitCacheSize that is smaller than
    the value specified for WinCacheSize, InitCacheSize is set to the same
    size as WinCacheSize.

The following table shows what the default values for InitCacheSize and
WinCacheSize will be, depending on the amount of available extended memory
your computer has.

Extended         InitCacheSize        WinCacheSize
Memory
---------------------------------------------------------------------------

Up to 1 MB       All extended         Zero (no caching)
                 memory

Up to 2 MB       1 MB                 256K

Up to 4 MB       1 MB                 512K

Up to 6 MB       2 MB                 1 MB

6 MB or more     2 MB                 2 MB

Switches

/X
    Disables write-behind caching for all drives. You can then enable
    caching for individual drives by using the drive+|- parameter.

/U
    Does not load the CD-ROM caching module of SMARTDrive even if you have a
    CD-ROM drive. If SMARTDrive is loaded with the /U switch, you cannot
    enable CD-ROM drive caching. If SMARTDrive is loaded without the /U
    switch, you can disable or enable caching individual CD-ROM drives using
    the drive+|- parameter.

/C
    Writes all cached information from memory to cached disks. SMARTDrive
    writes information from memory to the disk at times when other disk
    activity has slowed. You might use this option if you are going to turn
    off your computer and want to make sure all cached information has been
    written to the disk. (SMARTDrive writes all cached information to the
    disk if you restart your computer by pressing CTRL+ALT+DELETE, but not
    if you simply turn off the power or press your computer's reset
    button.)

/R
    Clears the contents of the existing cache, including writing all
    write-cached information to disk, and restarts SMARTDrive.

/F
    Writes cached data after each command completes. This is the default
    value.

/N
    Writes cached data when the system is idle. When the command prompt
    returns, not all cached data may be written yet. To ensure that all the
    cached data is written, use the /C switch.

/L
    Prevents SMARTDrive from automatically loading into upper memory blocks
    (UMBs), even if there are UMBs available. You can use the /L switch if
    upper memory is enabled for use by programs. If you are using
    SMARTDrive's double-buffering feature and your system appears to be
    running slowly, try adding the /L switch to the SMARTDrive command in
    your AUTOEXEC.BAT file.

/V
    Instructs SMARTDrive to display status and error messages when it
    starts. (By default, SMARTDrive does not display any messages unless it
    encounters an error condition.) The /V switch cannot be used in
    conjunction with the /Q switch.

/Q
    Instructs SMARTDrive not to display status messages when it starts. (By
    default, SMARTDrive does not display status messages when loading, but
    does for most other operations.) If SMARTDrive encounters an error while
    starting, it displays an error message whether or not it was loaded with
    the /Q switch. The /Q switch cannot be used in conjunction with the /V
    switch.

/S
    Displays additional information about the status of SMARTDrive.

/E:ElementSize
    Specifies in bytes the amount of the cache that SMARTDrive moves at a
    time. Valid values are 1024, 2048, 4096, and 8192. The default value is
    8192. The larger the value, the more conventional memory SMARTDrive
    uses.

/B:BufferSize
    Specifies in bytes the size of the read-ahead buffer. A read-ahead
    buffer is additional information that SMARTDrive reads when an
    application reads information from the hard disk. For example, if an
    application reads 512K of information from a file, SMARTDrive then reads
    the amount of information specified by BufferSize and saves it in
    memory. The next time the application needs to read information from
    that file, it can read it from memory instead. The default size of the
    read-ahead buffer is 16K (16384 bytes). Its value can be any multiple of
    ElementSize. The larger the value of BufferSize, the more conventional
    memory SMARTDrive uses.

Caution:  Check that SMARTDrive has completed all write-caching before you
          restart  or turn off your computer. (This is not necessary if you
          restart your computer by pressing CTRL+ALT+DELETE.) To have
          SMARTDrive write all cached information to cached disks, type
          SMARTDRV /C at the command prompt. After all disk activity has
          stopped, you can safely restart or turn off your computer.

                                      ***

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                              SMARTDRV--Notes

Enabling write caching on specific drives

By default, MS-DOS Setup configures SMARTDrive so that write-caching is
disabled. This configuration is extremely safe, but does not provide optimum
speed. After SMARTDrive starts, you can use the SMARTDRV command to enable
write caching on specific drives. This can significantly speed up your
system. To enable write-caching on a particular drive, carry out the
SMARTDRV command and specify the drive letter and a plus sign. For example,
to enable write-caching on drive C, you would type the following:

    smartdrv c+

For information about enabling write-caching for compressed drives, see
"SMARTDrive and Compressed Drives" later in this help topic.

Using extended memory

For SMARTDrive to use extended memory, your CONFIG.SYS file must contain a
DEVICE command for HIMEM.SYS or another extended-memory manager that
conforms to the Lotus/Intel/Microsoft/AST eXtended Memory Specification
(XMS).

Loading SMARTDrive into the upper memory area

If the upper memory area is available through MS-DOS, SMARTDrive will
automatically load into upper memory. You do not need to use the LOADHIGH
command with SMARTDrive.

If your hard disk requires double buffering, SMARTDrive may run faster if
its cache is located in conventional memory. To load SMARTDrive into upper
memory and its cache in conventional memory, use the following command:

    loadhigh smartdrv /l

SMARTDrive and compressed drives

SMARTDrive does not actually cache compressed drives; instead, it caches the
physical (host) drive on which the compressed volume file is located. This
improves the speed of both the physical drive and the compressed drive.

SMARTDrive and CD-ROM drives

If you are using a CD-ROM drive and you want to cache it, load MSCDEX before
you load SMARTDrive. If you do not want to cache the CD-ROM drive, load
SMARTDrive with the /U switch. (Note that MS-DOS Setup adds the SMARTDRV
command to the beginning of your AUTOEXEC.BAT file, before any other
commands.)

To find out whether SMARTDrive is caching your CD-ROM drive, type SMARTDRV
at the command prompt.

                                      ***

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                             SMARTDRV--Examples

To create a SMARTDrive disk cache and use the default cache size, add the
following command to your AUTOEXEC.BAT file:

    c:\dos\smartdrv

Example: A typical SMARTDrive command

Suppose you want to create a disk cache with a cache size of 2048K, and
ensure that Windows will not reduce the size of the cache to less than
1024K. To do this and to specify that the SMARTDRV.EXE file is located in
the DOS directory on drive C, add the following line to your AUTOEXEC.BAT
file:

    c:\dos\smartdrv 2048 1024

Example: Enabling and disabling caching on specific drives

Suppose that SMARTDrive is already running and you want to enable write
caching on drive C. To do this, type the following at the command prompt:

    smartdrv c+

Suppose you want to configure SMARTDrive to disable all caching of your
floppy-disk drives and enable write caching on Interlnk drive D. (Interlnk
drives, like floppy-disk drives, are not write-cached by default because
it's possible to lose access to the drive before all information has been
written from the cache). To do this, you would add the following command to
your AUTOEXEC.BAT:

    c:\dos\smartdrv a- b- d+

Example: Saving cached information on the hard disk

Before pressing your computer's reset button or turning off your computer,
it is a good idea to have SMARTDrive write all cached information from
memory to any cached disks. To do this, type the following at the command
prompt:

    smartdrv /c

You will not need to use this command before restarting your computer by
pressing the CTRL+ALT+DELETE keys: SMARTDrive detects the CTRL+ALT+DELETE
key sequence and automatically writes all information to cached disks before
allowing the system to restart.

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