new hdd numeration after mainboard change

[Josh Paetzel]

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Jeremy Chadwick wrote:
> On Mon, Oct 13, 2008 at 07:12:20PM +0200, ilikefbsd at web.de wrote:
>> i run "FreeBSD  7.1-PRERELEASE" i had a change of the mainboard of my
>> lenovo notebook t60. after reboot the harddisk which was before
>> recognized as "ad0" is now "ad4". i cannot find any other devices, no
>> ad0/ad1/ad2 in /dev. even in the dmesg only ad4
> 
> The T60 is a laptop.  It only has one hard disk -- so I'm not sure why
> you were seeing ad0, ad1, ad2 in the past.  You shouldn't have been,
> unless you had 3 hard disks hooked up somehow.
> 
> The bottom line here is this: absolutely *nothing* requires the device
> numbering to start at zero.  And this is definitely the case.
> 
>> does fbsd create a uniqe identifier for harddisks in combination with
>> the motherboard or something like that?  where can i dig further into
>> that issue?
> 
> It's not really an "issue".  Very likely your computer has toggled some
> BIOS settings.
> 
> The T60 series has the ability to run the SATA ports in two modes: AHCI,
> or Enhanced/Compatible.  Chances are before the motherboard swap, yours
> was running in the opposite mode that it is now.
> 
> I would highly recommend using the AHCI mode.  It works quite well with
> FreeBSD under Intel controllers.  Turn AHCI on (if it's not already),
> and do not mess with it.
> 

I can verify as a T60 owner, if you toggle the BIOS between AHCI and
"Compatability" the hard drive will show up as either ad4 or ad0.

It works fine in either mode with FreeBSD.  Unless you are running
another OS that doesn't have SATA support there's really no reason to
use compatibility mode

- --
Thanks,

Josh Paetzel

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