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From: m5@lynx.UUCP (Mike McNally)
Newsgroups: comp.periphs,comp.unix.wizards
Subject: Re: query: new disk drive for VAX
Message-ID: <4559@lynx.UUCP>
Date: 6 Oct 88 22:24:28 GMT
References: <4198@bsu-cs.UUCP> <3531@phri.UUCP> <10199@eddie.MIT.EDU> <18529@uflorida.cis.ufl.EDU> <10209@eddie.MIT.EDU>
Reply-To: m5@lynx.UUCP (Mike McNally)
Organization: Lynx Real-Time Systems Inc, Campbell CA
Lines: 27

In article <10209@eddie.MIT.EDU> jbs@fenchurch.MIT.EDU (Jeff Siegal) writes:
>Not true.  Maxtor offers a version of its drive which supports
>synchronous SCSI and claims 4MB/s transfers.  

One must be careful when looking at performance specifications
published by drive manufacturers.  Often, the performance analyses are
done by reading a megabyte or two in one command.  This is all well and
good, but doesn't say much about performance in a UNIX environment.
It's important to know how fast the drives execute SCSI commands.  We
tried some drives here (I can't remember which manufacturer) that
resonded to SCSI read requests so slowly that it lost a revloution on
each read!  We tried an 8-inch Fujitsu thing that was really slow, even
though it had very high performance claims.

In principle, I agree that SCSI can have very good performance.  It's
danged convenient, too.

One interesting thing about Maxtors: we have a 5.25 inch full-height 
SCSI drive (170MB).  It only responds to the "test unit ready" command
when it's ready; otherwise, the command isn't acknowledged.  Think
about it.

-- 
Mike McNally                                    Lynx Real-Time Systems
uucp: {voder,athsys}!lynx!m5                    phone: 408 370 2233

            Where equal mind and contest equal, go.