From: Stuart F. Biggar (Stuart.Biggar_at_opt-sci.arizona.edu)
Date: Tue Oct 03 2000 - 08:55:03 EDT
If I remember correctly, the 32 GB rotates faster hence
it takes less time for a given sector to arrive under
the head. Therefore, drives that rotate faster have
lower latency - the computer can get the data with
a lower average delay (on the order of milliseconds).
For a given bit density (linear), the faster a drive
rotates, the higher the data rate. However, the bit
density depends on the magnetic material and the heads.
Recent notebook drives can use really high bit density
giving a higher data rate at a given RPM.
If I remember correctly, the 20/30 GB drives use a
higher bit density than the 32 GB but the RPM difference
with the 32 GB yields a higher data rate off the heads.
However, the data rate depends on what zone of the drive
the heads are actually reading from (more data on outer
tracks than inner ones).
The drives use the same interface so the burst rate
>from the interface to the computer would be the same.
Hence, I would expect the sustained data rate from the
32 to be somewhat higher that the 20/30 and that the
latency would be lower so the 32 GB drive would be
"faster" is several respects.
Stuart
At 02:09 AM 10/3/00 -0400, you wrote:
>RPM almost always does indicate speed, in that the faster a
>disk revolves the faster the disk is positioned under the
>head again to get more data. Now you could I suppose come
>up with a strange enough system that extra speed wouldn't
>matter, but that isn't the way most disks are these days.
>
>Hmm. The www.ibm.com/storage web site should list all the
>details on all the disks. When I have time I'll look there...
>
>--STeve Andre'
>
> >
> > > One person described the increase as "noticeable, but not
> > > dramatic."
> >
> > Between the 30 vs 32 Gig or the 30 vs the 12 Gig?
> >
> >
> >
> >
> > BTW - RPM does not necessarily dictate speed. Right?
> >
> > Thought exercise:
> >
> > If I pack in 30gigs onto a disk instead of 12Gigs, wont the 30gig be
> reading
> > more data per revolution of the disk?
> >
> > Would be nice to see all the real specs. Seek time, burst throughput, and
> > other specs that I'm guessing HDD makers slap onto their device.
> >
> > -Will
> >
> > > -----Original Message-----
> > > From: Emanuel Brown [mailto:epbrown01_at_att.net]
> > > Sent: Tuesday, 3 October 2000 6:47 a.m.
> > > To: thinkpad_at_cs.utk.edu
> > > Subject: Re: The speed of the 30 Gig Drives
> > >
> > >
> > > On Tue, 3 Oct 2000 02:37:04 +1300, you wrote:
> > > >Are these new IBM drives any faster than say my 12Gig Travelstar?
> > > >Or the 18-20 Gig HDDs?
> > >
> > > The only 12.5mm drive faster than 4200 rpm is the 32GH, which is
> > > 32GB and 5411 rpm.
> > > >
> > > >Any real world increase in speed?
> > >
> > > One person described the increase as "noticeable, but not
> > > dramatic."
> > > Emanuel
> > > "Everybody wants a normal life and a cool car;
> > > most people settle for the car." Chris Titus
> > > 1983 911 SC
> > > http://home.att.net/~epbrown01/91183.jpg
> > >
> >
> >
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