[ale] SATA II

[Greg Freemyer]

On 3/12/07, Cox, Danny <dcox at icc.net> wrote:
> Chris,
>
> -----Original Message-----
> From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of
> Christopher Fowler
> Sent: Monday, March 12, 2007 1:21 PM
> To: ale at ale.org
> Subject: [ale] SATA II
>
> I'm in the process of spec'ing new hardware for our servers.  I'm
> looking at using the SATA II capabilities of the new hardware.  Are
> there any issues with Linux using SATA II?  I'm looking at the migration
> to increase the speed of the drives.
>
>         See http://linux-ata.org/driver-status.html for Jeff Garzik's
> information on SATA drives.  I'd pick one that supports Native Command
> Queueing (NCQ), which can really make a difference on fileservers.  I've
> also read that the typical desktop user won't see any improvement, so
> take your choice!
>

Is your NCQ info Linux specific?  I follow the lkml-ide mailing list
and what I've read is that under linux NCQ is a very small gain most
of the time.

IIRC to test that NCQ is working they actually have to have the kernel
not use its normal elevator sort disk queueing algorithms. In that
situation NCQ allows the drive to optimize the
disk writes to optimize head movement, but with the default elevator
sort enabled in the kernel the disk does not have much ability to
optomize it any more than the kernel does already.

As to the original question, I have not tried SATA 300 drives yet.
Apparently some of them do cause problems with the current kernel,
with some specific controllers, computers, etc..  The good news is
that it seems there is apparently a jumper on those drives to slow it
down to 150 mode.

If you're really curious you can search the lkml-ide mailing list.

Greg
-- 
Greg Freemyer
The Norcross Group
Forensics for the 21st Century