Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!apple!sun-barr!newstop!texsun!letni!merch!cpe!adaptex!neese
From: neese@adaptex.UUCP
Newsgroups: comp.unix.xenix
Subject: Re: 386GT Adaptec SCSI performance :-(
Message-ID: <7100003@adaptex>
Date: 12 Jul 89 13:46:00 GMT
References: <11166@tapa.uucp>
Lines: 30
Nf-ID: #R:tapa.uucp:11166:adaptex:7100003:000:1144
Nf-From: adaptex.UUCP!neese    Jul 12 08:46:00 1989


>We recently put an ADAPTEC 1540A SCSI into a Compaq 386/20 as a second disk
>controller using 2.3.2GT.  The first contoller is the Compaq supplied WD1007.
>Performance on the SCSI disks are worse (I'm being kind) than were expected. 
>Here are some performance numbers all in kb/sec.:
>
>	disk		raw device	block device	large file
>
>	ESDI		340		319		288
>
>	SCSI		107		 57		 56
>
>The ESDI is a Compaq supplied 300mb Minisribe and the SCSI disks (2) are CDC
>Wren IV also 300mb.  The ESDI file system is fairly new and the SCSI file
>system is virgin.  BTW the correlation of block device to large file is worth
>noting in light of the benchmarks published here a week or so ago.
>
>I tried reformatting with adfmt but got an error.  Also the 1540A was jumpered
>for both sync and async negotiation with no change.
>
>Anybody have any ideas?

CDC by default ships the Wren IV drives with the read ahead buffer disabled.
If you enable this via the mode sense/select commands, then you will see
about a 400% increase in throughput.


			Roy Neese
			Adaptec Central Field Applications Engineer
			UUCP @ {merch,texbell,killer}!cpe!adaptex!neese