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From: FelineGrace@cup.portal.com (Dana B Bourgeois)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: Seagate Drives
Message-ID: <42421@cup.portal.com>
Date: 17 May 91 06:33:39 GMT
References: <9105152355.AA05412@thunder.LakeheadU.Ca>
Organization: The Portal System (TM)
Lines: 45

On a related note:

Seagate tells me they will be announcing/shipping a new (very large)
drive this fall.  It is about 2.4 Gbyte unformatted.  I asked because
I am spec-ing a Sun SPARC at work and want the largest drives I can
get my hands on.  One of the specs intruiged me.  Throughput.  I have 
seen this spec quoted several different ways and I am wondering about
it.  Peak numbers are quoted and sustained numbers.  Sometimes just
numbers.  The units are either MegaHertz or MegaBytes/Minute.  Now the
guy I talked to said the rotation speed is to be 3600 RPM and yet he
claims a thruput of 10 MegaBytes/Sec (I said 'minute' up above.  So I
messed up!  Shut up!  --E. Murphy).  Now I tried to convert that to a
sustained megahertz number and came up with 80 MHz so I think the 10 MB/S
is the SCSI burst speed not the hard drive device sustained speed.  

OK, finally for my questions:

	1. What is the fastest sustained throughput drive the Amiga
           can handle?  20 MHz?  28MHz?  What if any 'magic' is needed
           to handle such a drive?  Controller/memory/etc.

	2. Sun and other workstation vendors already claim to use
           SCSI 2.  Does CBM have plans to support it?  I'm not asking
	   about products.  More design philosophy.  Will SCSI 2 give
	   enough increase in speed to make a viable product as opposed
	   to a 'me-too' marketing product.

	3. I see transfer rates being batted around in workstation/unix
	   magazines of 4-5 MB/sec.  Used to be people on this thread
	   said the Amiga's 1.2 MB/s SCSI was one of the fastest SCSI
	   implementations going.  I've seen Amiga numbers around 2 MB/s.
	   Have SCSI designs on other machines really tripled/quadrupled
	   in speed?

	4. Assuming that sustained throughput is an important spec for
	   hard drives, anybody know a good rule-of-thumb for estimating
	   the speed of a drive given a few common factors like, average
	   seek time, rotation speed, max bit density/unformatted capacity?
	   Seems like you should be able to do this.

Thanks in advance

Dana Bourgeois @ cup.portal.com

"Why do I ask such dumb questions?  All the good ones are already taken!"