386GT Adaptec SCSI performance :-(

[Rick Francis]

In article <1989Jul10.175106.11166 at tapa.uucp> larry at tapa.uucp (Larry Pajakowski) writes:
>
>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

We also have 300MB CDC drives with the Adaptec 1540A.  When we first installed
the drives, we had about the same performance you're getting.  We had the
drive vendor re-format the drive with 1:1 interleave and enable read-ahead.
We now see raw device performance of about 350 KB/SEC.

Also, the REAL advantage with SCSI shows up when you have multiple drives
with your I/O load balanced between them.  Plus, SCSI uses less CPU
time for disk transfers than ESDI.

Rick Francis