SATA Drives - Do they have data transfer modes or a rough equivalent to data transfer modes?

jdana
jdana used Ask the Experts™
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Take a look at the table titled Features introduced with each ATA revision on the following Wikipedia page:

http://en.wikipedia.org/wiki/Parallel_ATA#EIDE_and_ATA-2

Do SATA drives have transfer mode or transfer rate classifications that are remotely similar to these?
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dbruntonQuid, Me Anxius Sum?  Illegitimi non carborundum.
Commented:
See http://en.wikipedia.org/wiki/Serial_ATA

But, note, these are theoretical speeds.  What you get in practice will be less.
The main modes you need to concern yourself with are:

SATA1  (1.5gb/s theoretical bus speed)
SATA2  (3.0gb/s theoretical bus speed)
SATA3  (6.0gb/s theoretical bus speed).

They are backwards compatible, so a motherboard that supports SATA3 will accept a hard disk that only supports SATA2.

Most hard disks (at least all the ones I know of from Seagate and Western Digital) are also backwards compatible as well. A hard disk that can run at SATA3 speeds will be happy in a SATA2 port.

Like dbrunton suggested, the BUS speed at SATA is a theoretical maximum and usually it is the hard disk itself will limit the transfer speed (a typical modern hard disk today transfers data at around 700-1000mbps, a far cry from even the lowest SATA 1.5gbps limit).

Compatibility with SATA is a lot better than it was with IDE. No master/slave, no jumpers for the most part, and no significant capacity limitations. Many motherboards even support hotswapping. It's a very user-friendly interface.
President
Top Expert 2010
Commented:
Yes, they do.  First, they have the interface speeds of 1.5, 3.0 & 6.0Gb/sec.
But that is just interface speed.  They also have programmable data transfer modes and support for various classes of low-level transport commands relating to Ultra DMA modes 1-6;  read & write streaming command sets; multiword DMA sets;  queue depth; NCQ, DMA optimization ...

The writer of the device driver has a great deal of flexibility when it comes to choosing what commands to take advantage of.  A crappy device driver and/or kernel/OS interface that isn't tuned for later-generation drives won't be able to take advantage of them.

Same for firmware and controllers.  So just because an interface speed may be "supported" and even used in the O/S, SATA controller, and disk itself, you won't see any performance improvement if the architects didn't take advantage of some instruction set families that could use it.

Conversely you may have some SATA-1 disks with well-written drivers only sync up at 1.5Gbit/sec, but in the real-world, they may outperform a SATA-3 disk because all these geeky internal configurable parameters inherent in the architecture may be turned on for a certain SATA-1 implementation, but isn't turned on in a SATA-3 system.
noxchoIT Product Manager
Top Expert 2009

Commented:
Your SATA drive will use the max available speed of the SATA controller given by your mobo. So no need to worry about that.

Author

Commented:
Thanks for the thoughtful responses.

J

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