[lug] hard drive speeds

[Ferdinand P. Schmid]

You forgot the caching aspect in this.  IDE based hard drives usually
have less than 512 kB of cache, while good SCSI controllers provide
several megabytes of cache.

Typically your hard drive spins 1/2 a revolution in the seek process. 
Then it can start reading and the data throughput there is limited by
the track density and rpm in addition to bus limitations.

Bottom line:  For a user who mostly accesses only one file at a time a
good IDE drive is acceptable.  For multi-file access the caching and
usually higher rpm of SCSI drives really pays off.  In my experience IDE
often looked good on paper but the real performance came with SCSI
drives.

Ferdinand

"Harris, James A (Jim)" wrote:
> 
> Well, I don't have any experience with them yet, but the Ultra-2 drives that
> are being made should be the fastest.  I know that Tekram and Adaptec are
> both making cards that support this SCSI level.  (Prob. more are, but I
> haven't really looked around for 'em.)  As far as I can see the average
> spindle speed of these drives is around 10,000 RPM (Seagate Cheetah is an
> example) and most are seeing an average seek time of around 5-6ms.  By the
> specs alone, these little monkeys outa smoke.  They're very expensive, but
> for the performance it's probably worth it.  Ultra-2 is (correct me if I'm
> wrong) 10 or 20MB/sec faster than Ultra-wide.
> 
> For a cheaper solution there's the new Ultra-ATA66 standard.  Again, it's
> new enough that I haven't played with it, but they're claiming to be getting
> 66MB/sec burst off of the drives.  They're also averaging spindle speed
> around 7,200RPM.  Dunno the seek times, but I'd imagine once more mobo
> makers start integrating the controllers, this will become a good cheaper
> solution.
> 
> My two cents...
> 
> -----Original Message-----
> From: Michael J. Hammel [mailto:mjhammel at graphics-muse.org]
> Sent: Tuesday, September 28, 1999 1:48 PM
> To: lug at lug.boulder.co.us
> Subject: [lug] hard drive speeds
> 
> Question to you hardware experts:  what are the fastest hard drives
> available?  Don't SCSI drives generally have faster throughput and
> read/write times than IDE?
> 
> I'm working on a talk I'll be giving at ALS on the Gimp and one of the
> major bottlenecks for graphic artists when using the Gimp is swapping tiles
> from memory to disk and back.  My understanding is that the faster buses
> being introduced in PCs these days aren't helping IDE throughput, but they
> might help SCSI subsystems using add-on cards, right?
> 
> Anyone want to take a crack at what drives are generally going to provide
> the fastest throughput?
> --
> Michael J. Hammel           |
> The Graphics Muse           |   Books we'll never see:
> mjhammel at graphics-muse.org  |      "The Amish Phone Directory"
> http://www.graphics-muse.org
> 
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-- 
Ferdinand Schmid
(Staff Engineer)

Architectural Energy Corporation
http://www.archenergy.com
2540 Frontier Avenue, Suite 201
Boulder, CO 80301
Phone:	(303) 444-4149
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e-mail:	mailto:fschmid at archenergy.com