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From: jl@fornax.uucp (JL)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Hard Drive dir problem
Message-ID: <340@fornax.uucp>
Date: Mon, 13-Jul-87 10:28:55 EDT
Article-I.D.: fornax.340
Posted: Mon Jul 13 10:28:55 1987
Date-Received: Wed, 15-Jul-87 01:12:20 EDT
References: <3774@garfield.UUCP> <7083@shemp.UCLA.EDU> <494@amc.UUCP>
Organization: School of Computing Science, SFU, Burnaby, B.C. Canada
Lines: 57

> In article <3774@garfield.UUCP> robert4@garfield.UUCP writes:
> >
       [ Question about why the FIRST acces to a directory after a cold
         boot results in the hard drive being accessed continuously for
         about 5-10 seconds BEFORE the dir listing comes up on the screen.]
> In article Jon Mandrell, Applied Microsystems Corp., (ihnp4!uw-beaver!tikal!amc!jon)

> My system does the same thing, and after poking around I tracked it down
> to the BUFFERS= entry in CONFIG.SYS.  It turns out that some clusters are
> getting buffered in memory, so that the next time you access the directory
> it just looks in memory.  On mine, I can enter an invalid command, and the
> disk will whir and I will get an error message, and then if I do it again,
> it comes back immediately with an error message.
> 
> P.S. If you really want to speed up operations (with a fast hard disk), and
>      you can afford the memory, set your buffers to a larger number (I use
                                  ***********************************

>      64, and have been tempted to go larger).


     RTFM.   :-)

     For example, try pages 4-7 through 4-10 of the IBM PC-DOS
reference manual for ver 3.20

     In particular, note the suggestion above about using very
large buffers.  I quote the following from page 4-9 of the above
cited reference.

          "For most data base applications, a value between 10 and 20
     buffers usually provides the best results.  For subdirectories,
     between 10 and 25 buffers usually provides desirable performance.

          Beyond that point, the system may appear to start
     RUNNING SLOWER [caps are mine].  With a very large number of
     buffers, it can take DOS longer to search all the buffers for
     a record than it would take to read the record from disk."


     ...

          "Since each additional buffer increases the resident size of
     DOS by 528 bytes, the amount of memory available to the application
     is reduced by that amount.  Additional buffers may actually cause
     some applications to run more slowly because there is less memory
     available for the application to keep data.  This could result in
     more frequent reads and writes than would otherwise be necessary."



     Please keep this in mind when you select a BUFFERS size.



-- 
Jay-El