Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!rutgers!cbmvax!jesup
From: jesup@cbmvax.commodore.com (Randell Jesup)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: Daisy chaining SCSI drives----benefit??
Message-ID: <17657@cbmvax.commodore.com>
Date: 16 Jan 91 02:09:54 GMT
References: <1991Jan15.211044.3827@csusac.csus.edu>
Reply-To: jesup@cbmvax.commodore.com (Randell Jesup)
Distribution: na
Organization: Commodore, West Chester, PA
Lines: 25

In article <1991Jan15.211044.3827@csusac.csus.edu> maltasr@csusac.ecs.csus.edu (Robert Maltas) writes:
>I was joining together 2 files a week ago and noticed quite a bit of thrashing
>on my hard drive. I have a GVP Series II card and 210 meg Quantum ProDrive.
>One of the two files I was joining was 6 megs, so I placed this in a RAM:
>disk; the other file was 1.5 megs, which resided on my hard drive. The file
>which was formed by the JOIN command was directed to the same hard drive 
>(where the 1.5 meg file  resided).

>If I had a second hard drive, so that the newly formed file was created
>on that hard drive (i.e. no 2 files are on the same device now), would
>this get rid of heavy disk thrashing?

	Yes, most of it.  Join is usually used on small files, and uses
normal buffered input (which has ~200 byte buffers), so it does a lot of
single-block reads and writes.  On a single drive, this may mean a lot of
seeking back and forth.  Increasing the number of buffers may help somewhat,
but not incredibly.  A program that does large reads/writes would be MUCH
faster than even the 2-drive solution.

-- 
Randell Jesup, Keeper of AmigaDos, Commodore Engineering.
{uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.commodore.com  BIX: rjesup  
The compiler runs
Like a swift-flowing river
I wait in silence.  (From "The Zen of Programming")  ;-)