Bob Friesenhahn <[EMAIL PROTECTED]> wrote:
> On Wed, 1 Oct 2008, Joerg Schilling wrote:
> >
> > SATA and SAS disks usually base on the same drive mechanism. The seek times
> > are most likely identical.
>
> This must be some sort of "urban legend". While the media composition
> and drive chassis is similar, the rest of the product clearly differs.
> The seek times for typical SAS drives are clearly much better, and the
> typical drive rotates much faster.
Did you recently look at spec files from drive manufacturers?
If you look at drives in the same category, the difference between a SATA and a
SAS disk is only the firmware and the way the drive mechanism has been selected.
Another difference is that SAS drives may have two SAS interfaces instead of the
single SATA interface found in the SATA drives.
IOPS/s depend on seek times, latency times and probably on disk cache size.
If you have a drive with 1 ms seek time, the seek time is not really important.
What's important is the latency time which is 4ms for a 7200 rpm drive and only
2 ms for 15000 rpm drive.
People who talk about SAS usually forget that they try to compare 15000 rpm
SAS drives with 7200 rpm SATA drives. There are faster SATA drives but these
drives consume more power.
Jörg
--
EMail:[EMAIL PROTECTED] (home) Jörg Schilling D-13353 Berlin
[EMAIL PROTECTED] (uni)
[EMAIL PROTECTED] (work) Blog: http://schily.blogspot.com/
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