Many years ago, we learned, on an IBM mainframe (slow by today's standards) that we could drastically increase thru put by separating certain files to different disk drives.  This reduced head contention.

I am wondering if the same distribution of files across a cluster (separate disk drives) might also increase performance.  Granted, the drives back then had a 25 ms average seek time and today that number is less than 10.

It's a thought.

George

> -----Original Message-----
> Date: Tue, 13 Jul 2004 11:13:11 -0700
> From: "Kevin Brown" <kevin_brown@qwest.net>
> To: plug-discuss@lists.plug.phoenix.az.us
> Subject: Re: cluster software
> 
> > A real clustering newbie question....
> > 
> > Would a cluster of several PCs using Pentium processors running
> > apache/tomcat be equivalent in throughput a single PC with 
> a Pentium III or
> > IV processor running apache/tomcat as a web server serving 
> JSPs and running
> > Java code?
> > 
> > Just curious as I have some old Pentium and Pentium IIs 
> that are ready for
> > the junk pile.
> 
> There are two reasons for utilizing clusters.
> 
> 1) You have a problem that can be broken into smaller chunks 
> and the output when 
> recombined gives you the overall solution.
> 
> 2) You want to divide the load of an application across 
> multiple systems to help 
> it scale.
> 
> Type 1 would be what a lot of clusters are being built for in the 
> scientific/research area.  Take a large, comlex problem and 
> divide it into 
> smaller, more manageable chunks to get to a solution
> 
> Type 2 sounds more like what you are describing with Apache/Tomcat.
> 
> Will you get equivalent performance? This depends on the 
> number of users hitting 
> the system and the way the application is built (e.g. what is 
> it designed to 
> do).  If it is a single user/threaded application, most 
> likely, no...  If you 
> are getting lots of users hitting the systems or the 
> application can start up 
> multiple threads to deal with a request, maybe.
> 
> 
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