Path: utzoo!attcan!uunet!ogicse!husc6!encore!jcallen
From: jcallen@Encore.COM (Jerry Callen)
Newsgroups: comp.periphs.scsi
Subject: Re: Why Buy I-P-I?  SCSI is equally fast and 40% cheaper
Summary: Disk != Controller
Keywords: Hardware
Message-ID: <11593@encore.Encore.COM>
Date: 13 Apr 90 14:51:41 GMT
References: <6634@brazos.Rice.edu>
Reply-To: jcallen@encore.com (Jerry Callen)
Organization: Encore Computer Corp, Marlboro, MA
Lines: 40

In article <6634@brazos.Rice.edu> seeger@manatee.cis.ufl.edu (F. L. Charles Seeger III) writes:

> [quoted material deleted; was comparing IPI to SCSI transfer rates]
>
>Though modern SCSI drives are quite cost effective, the 4 MB/s transfer
>rate is misleading because this represents a drive cache to SCSI bus
>transfer.  The raw rate from the media to the cache varies with drives...
> [stuff deleted]
>...So, I take strong exception to the statement in the subject line that
>SCSI disks are as fast as the IPI disks.  They aren't.

If the discussion is about currently available storage subsystems, this may
be true. But there is absolutely NO reason why a SCSI-interfaced storage
subsystem can't use multiple heads, disk striping or other tricks to get
the "off-the-disk" data rate up. SCSI only defines the SCSI bus protocol,
it says nothing about the SCSI-to-controller interface.

>Getting the most reliable drives available is another lesson that we can all
>learn from them.  Seek times and tranfer rates aren't everything.

Amen!

>  Charles Seeger    E301 CSE Building        Work: +1 904 392 1508
>  CIS Department    University of Florida    FAX:  +1 904 392 1220
>  seeger@ufl.edu    Gainesville, FL 32611    Home: +1 904 375 1819

-- Jerry Callen
   jcallen@encore.com
   (508) 460-0500 (work)

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