serial ATA interface

David Kelly dkelly at
Fri Sep 24 09:49:21 PDT 2004

On May 14, 2003, at 5:00 AM, Ceri Davies wrote:

> On Tue, May 13, 2003 at 07:02:47PM -0700, David Bear wrote:
>> I just learned of the new hardware serial ata standard -- much faster
>> throughput, different form factor, etc.  does freebsd support it now
>> or does it look enough like standard ata that freebsd doesn't care?
> sos already committed support for a promise s-ata controller, making
> FreeBSD first to support this as far as I'm aware.
> I don't think that made it to -STABLE yet though.

I haven't tried it on the 4 branch but in 5.2.1 and 5.3-BETA SATA works 
just fine for me:

ad4: 157066MB <HDS722516VLSA80/V34OA60A> [319120/16/63] at ata2-master 
ad6: 157066MB <HDS722516VLSA80/V34OA60A> [319120/16/63] at ata3-master 

IIRC the SATA spec is downward compatible with PATA so at least in 
theory a SATA drive and interface will work everywhere.

As for speed and performance claims, "Bah humbug." The initial SATA 
interface is 150 MB/sec. I've never seen a single drive sustain over 55 
MB/sec. so as long as your interface is a bit faster than your hardware 
then its not an issue. Where the real gains are to be made is with the 
command set cleanup being undertaken with SATA. Useful multitasking 
features from SCSI are working their way into the 2nd generation of 
SATA drives.

SATA uses a nice small cable and connector. Each drive has its own 
cable without the master/slave silliness so there could/should be a 
performance increase where one uses both drives at the same time.

David Kelly N4HHE, dkelly at
Whom computers would destroy, they must first drive mad.

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