Subject: Re: CCL:Re: CCL:PCI vs. SCSI and Linux

From: "Rich McClellan" <[email-masked]>
Date: Tue, 28 Oct 1997 12:10:51 -0800

I apologize for replying to this email so long after it was originally posted,
but I have conducted some benchmarks on my system that you people may find
interesting.

My system:

	o PPRO 180 MHz (256 kb cache)
	o Buslogic BT-948 SCSI controller (fast, scsi-ii)
	o Conner fast, scsi ii disk (model no. elludes me, but it has
	  a 256kb cache and spindle rotation rate of 7200 rpm)
	o Triton chipset for EIDE controller
	o Seagate EIDE model no. ST3780A (256 kb cache, 4500 rpm)

	o Running the Linux OS of course :-)

Two factors that influenced my decision to install a SCSI controller and disk
were the perceived higher I/O of the SCSI disks and the smaller fraction of CPU
used during reads/writes.

Results:  The SCSI disk has throughput consistently higher than the EIDE disk
(probably due to the higher rpm) BUT when the EIDE disk is tune with the hdparm
utility to enable bus mastering and mulitple sector I/O, the throughout of the
EIDE drive increases but more notable the CPU usage GOES DOWN DRASTICALLY.
 Have a look at the benchmark results.

My conclusions:  Go with SCSI (preferably fast, wide), but EIDE properly tuned
is a cheap alternative.

***************************BENCHMARK RESULTS*********************************
(Note that sda is the scsi disk and hda is the eide disk)
On sda:
              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
entropy   100  4021 65.0  3848 21.9  1631 17.8  4758 57.0  4483 19.4  53.8  3.2

on hda:
Note:  drive NOT tuned with hdparm utility

              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
entropy   100  2642 82.4  2783 27.5  1140 37.7  2071 69.7  2589 59.7  32.3  4.7

on hda:
Note:  Drive tuned with hdparm utilities (-d1 -X34 -m32)

              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
entropy   100  3115 50.1  2750 12.4  1228 12.6  2557 29.0  2871 10.1  32.7  1.6

####################################
150 Mb cache
#############

SCSI drive
              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
entropy   150  4237 70.6  4241 22.7  1543 16.2  3167 37.3  4058 16.4  53.2  3.2

EIDE drive, hdparm on
              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
entropy   150  2794 44.2  2569 12.7  1179 11.9  2468 27.2  2758 10.1  28.0  1.3

*******************************************************************************
The benchmarks are called "bonnie".  You can get them from any Linux mirror
like Sunsite.

I hope these are helpful,
Rich

-- 
Molecular Engineering Laboratory		
Department of Chemistry and Biochemistry		
University of California, Santa Cruz