SOS Technical Reference Document
Copyright (c) 1994 by Synergistic Office Solutions, Inc.

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TOPIC..: Disk Caching
REVISED: 03/10/94

SUMMARY -------------------------------------------------------------------

There is no better way to inexpensively and dramatically improve the
performance of your system than to install disk caching software. Even a fairly small area of RAM set aside for this purpose will increase the
speed of many disk operations by 400% or more. The caching software
stores frequently accessed data in a reserved area of memory so that when
it is needed again it can be read almost instantly instead of retrieved
from your hard disk.

SMARTDRV.EXE --------------------------------------------------------------

Although almost any cache is better than none, there is a wide
differential in performance. Pretty much at the bottom of the heap is
the free disk caching software, called SMARTDRV that comes with MS-DOS versions 5 and higher, as well as with Microsoft Windows. SMARTDRV is slow, and the default installation, at least up through version 6.2 of DOS, if for the dangerous "write-caching" feature to be turned on. If you use SMARTDRV, it is ***ESSENTIAL*** that you disable the write caching feature in order to avoid almost certain file corruption. Here are some examples of lines you might find in your AUTOEXEC.BAT if you are using a recent version of DOS or have installed MS Windows:

C:\DOS\SMARTDRV.EXE BAD! Write-caching is enabled!
C:\DOS\SMARTDRV.EXE C+ BAD! Write-caching is enabled!
C:\DOS\SMARTDRV.EXE C DOS Ver 6.0, Windows: OK
C:\DOS\SMARTDRV.EXE /X Default DOS Ver 6.2: OK

The SMARTDRV line may also include other options and numbers. Example 2
above specifies the letter of a specific drive that you want to cache.
The absence of either a plus (+) or minus (-) after the drive letter
means that read operations will be cached, but writes will be done
immediately. That is what you want. What you do NOT want is the "C+"
situation, which specifically ENABLES write caching as well as read
caching. Remove the plus if you find it! For more information about
SMARTDRV, type HELP SMARTDRV at your DOS prompt. You can read the information on screen or print out a hard copy.

RECOMMENDED DISK CACHING SOFTWARE -----------------------------------------

The very first thing we want to emphasize is the need to disable all
write-caching features, no matter which software you use. We do not use it ourselves on any of our machines. Now, given that caution, caching software we can recommend includes:

SuperPCKwik included with the SuperPCKwik Power Pak and WinMaster products available from most software vendors.

Disk Caching Pg.2


NCache included with the Norton Utilities, available from most
software vendors.

PC-Cache From versions 5.5 through 7 of PC-Tools, NOT version 8
or 9. The newer versions are basically similar to SMARTDRV
and give roughly 25% of the performance of the high
performance programs. Earlier versions were subsets of
SuperPCKwik and were excellent.

HyperDisk This is a shareware ($50) program available on Compuserve
and many BBS's, including ours (904-242-9105). It is very 
fast and is reportedly stable running software similar to 
our applications. We have not tested it extensively.

Lancache Comes with Artisoft's Lantastic Network Operating System.
We have received several reports of serious file corruption
when running this cache program along with our software. We
strongly recommend that you do NOT use this program!


REDUCE BUFFERS SETTING WHEN USING DISK CACHING SOFTWARE -------------------

When using disk caching software it is not necessary, and may even
impede performance to specify more than a token number of BUFFERS in
your CONFIG.SYS file. We suggest reducing the number of BUFFERS to 3,
for example:

BUFFERS=3
BUFFERS=3,0

Check your DOS manual for the appropriate form for the version you
are using.

An explanation of how to modify your CONFIG.SYS file can be found in the help document "Editing CONFIG.SYS and AUTOEXEC.BAT".