Text 26873, 34 rader
Skriven 2007-01-16 13:01:38 av Jeff Guerdat
     Kommentar till en text av JAY EMRIE
Ärende: Re: duo core - what for?
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JAY EMRIE wrote:

> Maybe this is why my T60 seems faster - SATA.

Just an FYI - SATA defines the physical connection and command set.

The physical part is a serial bus that can transfer data at 150 or 
300MB/sec.  Of course, there isn't a drive available to mere mortals 
that can fill a UDMA66 bus and probably not a UDMA33 so it's a moot 
point.  The larger probability is that the drive is spinning at 5400RPM 
instead of the older laptops which used 4000 or 4200RPM.  That's why I 
saw a noticeable improvement in response on my old Dell 650MHz. PIII 
laptop a couple of years ago when I put in a 7200RPM drive.  The down 
side is that the CPU then stays busier, creating more heat (fan).  I 
didn't see any appreciable difference in battery life, however - it it 
were shorter, it wasn't by much.

The command set could also be a reason for peppier performance.  Most 
consumer-grade drives are relatively stupid and just do thing in the 
order in which they showed up in the queue.  Some (many?), but not all, 
SATA drives now have additional features such as "elevator seeks" where 
the drive controller orders things in the queue so that the heads don't 
go past a track that needs attention.  This leads to shorter, hence 
faster, seeks, bringing performance up with no difference in spindle 
speed or bus transfer rates.  These are features that have long been in 
SCSI drives and are finally making their way down.  However, SATA is 
just another ATA architecture, with many of the old shortcomings that 
the parallel (PATA) version has always had.  I was pretty disappointed 
in the Plextor SATA DVD writer I got, hoping for better system 
performance.  While it was a nice drive, it was very obviously limited 
by the ATA overall architecture that a PATA drive has but at a bit of a 
premium price...
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