From: keith@ksmith.uucp (Keith Smith)
Subject: Re: IDE faster than SCSI-2
Organization: Keith's Computer, Hope Mills, NC
Date: Sat, 07 Nov 92 18:36:35 GMT

In article <1992Nov5.094712.19056@ntuix.ntu.ac.sg> eoahmad@ntuix.ntu.ac.sg (Othman Ahmad) writes:
>[ Article crossposted from comp.unix.bsd,comp.os.linux ]
>[ Author was Othman Ahmad (eoahmad@ntuix.ntu.ac.sg) ]
>[ Posted on Thu, 5 Nov 1992 08:07:16 GMT ]
>
>I posted an iozone benchmark using my 386/25Mhz machine which shows that
>it is slightly slower than a SCSI-2 hard-disk. Now with a 486/33, IDE is
>definitely faster than a EISA SCSI-2 486/50MHZ  hard-disk.
>	Iozone uses normal unix system calls for writing to disks, after all,
>that is how we write C programs.
>	I may try to run a more sophisticated file system tester called
>bi? later on.
>
>
> JUlian's machine 
> is a 50MHz EISA 486 with a 1.3GB drive attached via a Bustek 742a SCSI2
> adapter. It has 16MB of ram. Part of the disk (about 200MB is taken up 
> by mach2.6 and is unavailable to 386bsd.
>
>I checked the load on this machine, it is very light. There is only another
>user apart from I.
>
>iozone 1
>
>Writing the 1 Megabyte file, 'iozone.tmp'...1.766667 seconds
>Reading the file...1.983333 seconds
>
>IOZONE performance measurements:
>	593534 bytes/second for writing the file
>	528694 bytes/second for reading the file
>

Too small a file. Try 8MB file.  These numbers are pretty *BAD*.  I do
much better than that with SCO 3.2.2 on SCSI-I disks (~ 1M/sec).  SCO is
not noted for filesystem speed either.  What are the sizes of your
buffer caches?

Also you are using 2 different machines.  I would imagine that the 50Mhz
486 EISA is tuned QUITE A BIT differently than the smaller 486/33 System
too.

What model 1.3G drive?  How fragmented the filesystem?  If the
Filesystem is fragmented badly you could be jumping around all over it
to write that 1M file.

>Running on 486/33 with 256Kbyte RAM cache, maxtor 200Mbyte IDE hard-disk,
>8Mbyte main RAM.

This is a very new and very fast & very small (comparatively) drive. 
*REMEMBER*, A LARGER filesystem has a logrithmic (not expotential)
increase in overhead as the size increases, and if fragmented, you could
easily be bouncing all over the disk to find the blocks you need.

>
>	Whereas the IDE runs XFree86 and open look window manager.
>I only use 1 megabyte for test file size.
>
>  IOZONE performance measurements:
>	873813 bytes/second for writing the file
>	452623 bytes/second for reading the file

And then ... You WROTE faster, but *READ* slower.  That means you wrote
to a buffer cache more than likely.  Again.  Use an 8MB or 16MB file for
a REAL test.  Also look at the WIDE difference here.  By all rights you
should READ faster than you write.

Then do a *SECOND* test.  Run IOZONE simultaneously in two windows on
each machines and record the results.  This MAY suprise you a bit.

>	Both machine uses 386bsd 0.1 heavily patched, so the timing measurements
>are consistent with each other.

Also,  it looks like your SCSI driver sucks, Also with only 1 disk and
everything else** equal SCSI won't be appreciably faster than IDE.

** everthing else = Seek time, size, bus master or pio, etc ad nauseum.
-- 
Keith Smith          uunet!ksmith!keith            5719 Archer Rd.
Digital Designs      BBS 1-919-423-4216            Hope Mills, NC 28348-2201
Somewhere in the Styx of North Carolina ...