[TriLUG] SAS vs. SATA performance

[Tim Jowers]

    I remember hearing back in '99 Seagate was still writing assembly for
Barracuda and wrote C code for Cheetah. When I bought a 500G SATA last year
and saw it was Barracuda I was amazed. I guess the Barracuda SCSI/SAS and
SATA drives are using the same microcode and posit they are using the same
hardware as well. Anyone know?
    I just wish my laptop had a fast drive. Forget power requirements, DOES
ANYONE KNOW of a simple way to put a fast SATA disk into a laptop? For now
I've been using an external, USB-connected drive.

TimJowers


On 7/26/07, Kevin Flanagan <flanagannc at gmail.com> wrote:
>
> I don't think that they were saying that the specs were what made the
> difference, but rather the grade of drives that are commonly used.  The
> difference between different Seagate disk platter sets could be something,
> the interface surely is different but doesn't make the
> difference.  Baracuda
> vs Cheeta drives, etc.
>
> I have skimmed the Google MTBF studies, they sure make a case, but at
> least
> I get 3 year warranty on SAS vs 1 year on SATA in Proliant servers.
>
>
>
>
> On 7/26/07, Robert Dale <robdale at gmail.com> wrote:
> >
> > On 7/26/07, Kevin Flanagan <flanagannc at gmail.com> wrote:
> > > There's a lot more to the difference, the drives themselves may in
> that
> > > order, but consider the controllers, channels etc.  Seek times,
> buffers,
> > > rotational speed are surely considerations, but SATA disks are
> generally
> > on
> > > a smaller number of channels and ports than SAS drives.
> > >
> > > Another consideration is the MTBF, HP advised me that the MTBF of a
> SAS
> > disk
> > > is 3 times greater than that of a SATA disk.
> >
> > I wonder if he gets paid 3 times for saying that...
> >
> > SAS and SATA are just buses, not a materials requirement, not a
> > manufacturing process, and not a mechanical specification.  Google and
> > CMU, separately, have put out some statistics on drive failures which
> > show MTBF means absolutely nothing and drive longetivity is completely
> > unpredictable.  Of course, the latest news is that drive failure is
> > caused by 'magnetic wobbles'.  So unless these are non-magnetic SAS
> > drives, you can safely ignore any MTBF sales-speak.
> >
> > HTH
> >
> > --
> > Robert Dale
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