Problems with ATA_CAM support in RELENG_8

Jeremy Chadwick freebsd at jdc.parodius.com
Thu Jul 1 12:46:08 UTC 2010


On Thu, Jul 01, 2010 at 08:26:31AM -0400, Paul Mather wrote:
> On Jun 30, 2010, at 5:21 PM, Jeremy Chadwick wrote:
> >> I'm assuming that "subclass = ATA" means the controller can't operate
> >> in AHCI mode.  The BIOS setting is also confusing.  It has two
> >> options, "Normal" and "Legacy."  "Normal" mode says, "The hard drive
> >> controller is configured for native mode.  This mode provides the
> >> highest drive performance and most flexibility."  I guess I
> >> misinterpreted "native mode" to be AHCI mode.
> > 
> > "Native", "Normal", and "Enhanced" are all terms used to describe the
> > controller operating in standard SATA (non-AHCI) fashion.  Dell's
> > in-BIOS description is nothing but schmooze; it's not the same as AHCI.
> > "Legacy" just means the controller appears and operates purely in
> > PATA-esque mode, so that you can use SATA drives on systems which don't
> > have SATA chipset drivers (ex. MS-DOS).
> 
> Thank you for helping clear that up.  I have a Supermicro
> X8ST3-F-based server here, and it offers three choices for drive mode:
> IDE, RAID, and AHCI.  I think it's much clearer, there, what you're
> getting.  Dell could learn a thing or two from them. :-)

It's a matter of demographic -- Dell often caters to home/residential
users, while Supermicro caters to engineers, SAs, and other highly
technical folk.  The latter excludes "gamers" or "tech forum freaks";
these two rarely, if ever, actually program or interface with the
devices or chips they're talking about.  Speculation on my part, but I'm
sure if you Google for "ICH8 ACHI" you'll find hundreds of posts on
random forums, and most of these posts will do nothing but confuse.  :-)

Dell started adding more technically-savvy options to their later
models, probably because of pressure from the above two groups, or
competitive pressure.  Hard to say.

> > Furthermore, I can assure you that the Dell OptiPlex 745 Mini-Tower
> > offers AHCI capability, and toggling its use via the system BIOS.  You
> > won't find it mentioned in Dell's "Tech Specs" PDF about this though.  I
> > realise this is not the system you have, but I'm simply pointing out
> > that it's a board manufacturer decision whether or not to provide the
> > capability, and that their decision obviously changed over the years.
> 
> Oddly enough, it *is* a Dell OptiPlex 745 in Mini-Tower configuration.
> This is the manual I'm led to via the service tag:
> http://support.dell.com/support/edocs/systems/op745/en/UG_en/mtindex.htm
> 
> Are you saying there is an option in the BIOS to enable AHCI on these
> systems?

Sorry for inducing confusion -- I meant the Dell OptiPlex 760.

At my workplace we literally have 4 different Dell OptiPlex models in
use as workstations.  I often mix up the model numbers, case in point.

I'm re-CC'ing the mailing list here, because I want to make sure my
mistake gets noted in case someone ends up searching the lists ("Hey! I
have a 745, what is this guy talking about?!?")

-- 
| Jeremy Chadwick                                   jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |



More information about the freebsd-stable mailing list