[ale] Related to my HDD ?

[Greg Freemyer]

On 7/13/07, Scott Castaline <hscast at charter.net> wrote:
> Calvin Harrigan wrote:
> > Scott Castaline wrote:
> >> I just realized that my SATA Host Adapter is the older 150 technology.
> >> It was made by Adaptec. I went to their site and it seems that they no
> >> longer make anything like mine in the 300 technology. For now can I
> >> connect a 300 drive to a 150 interface? Also any recomendations on a
> >> SATA300 HA? I do not need the raid capability, just a basic 2 or more
> >> drive interface that is a PCI card and not PCI-Express or whatever else.
> >>
> >> TIA
> >> _______________________________________________
> >> Ale mailing list
> >> Ale at ale.org
> >> http://www.ale.org/mailman/listinfo/ale
> >>
> >>
> > Yes you can connect a 300 to a 150 interface..  There isn't much to be
> > gained except for burst speed on the 300.  Sorta like the 66 vs 100 in
> > the early days.  You can't maintain 150 MB/s from any hard disk
> > currently in production.  You can just barely maintain half that.
> >
> >
> > Calvin...
> > _______________________________________________
> > Ale mailing list
> > Ale at ale.org
> > http://www.ale.org/mailman/listinfo/ale
> >
> Thank you, that's what I thought. Then I shouldn't need to replace my
> host adapter at this time. But I am still interested on hearing any
> personal experiences or preferences on this item. I am not sure how ever
> if I can have a 150 and a 300 on the same card. Also do SATA cards have
> the same traffic issues as standard IDE Master/Slave? Or since they only
> allow 1 drive per port that is not an issue.


Burst speed is good for multiplexing.  In SATA-land they call that
PMP.  PMP hardware is already out and many controllers are PMP
capable.  And there is a huge patchset trying to make its way into
2.6.23 to do this, but the merge window is closing fast, so it may be
2.6.24 (or later).

FYI: With PMP I don't know the max drives per sata port.  Anyone?

Anyway, to do PMP you need a PMP device.  (Like a USB-hub from a very
high-level).  You can get external Sata racks with a PMP built-in.
And I read yesterday that there is at least one MB with a PMP on it.

So without a PMP, Sata-150 is basically as fast as Sata-300, but with
a PMP, you can multiplex more drives together and utilize the higher
bandwidth.  Basically, if you have a PMP, you want to use a pure
sata-300 setup for best performance.  (I don't even know if PMP
supports sata-150 or not.)

FYI: Every Sata-300 controller I've seen was either on the MB or it
was PCI-Express.  I assume PCI can't keep up with the speed.

FYI2: Several of the sata bugs I've seen on lkml-ide have been
resolved by using that speed limiting Jumper.  aiui, not only is the
speed limited, but sata-2 features like NCQ are disabled as well, so
it is more of a Sata-1 vs sata-2 jumper than a sata-150 vs sata-300
jumper.

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