tying down adaX to physical interfaces

[Freddie Cash]

On Sat, Mar 26, 2011 at 3:09 AM, Jeremy Chadwick
<freebsd at jdc.parodius.com> wrote:
> On Sat, Mar 26, 2011 at 11:54:44AM +0200, Kostik Belousov wrote:
>> On Fri, Mar 25, 2011 at 10:16:43PM -0700, Jeremy Chadwick wrote:
>> > Why would the disk number change on a drive swap?  This doesn't happen
>> > on my Intel ICH9R controller on *any* Supermicro X7xxx or Supermicro
>> > PDxxx board I have access to.
>> Because the order of enumeration of controllers depends on the
>> BIOS, and is not consistent among boots. Also, it changes if you
>> swap controllers or insert disks into the free bays in the backplane.
>
> Re: insert disks into free bays: it behaves as I described in my post
> (paragraph #7):
>
> http://lists.freebsd.org/pipermail/freebsd-fs/2011-March/011039.html
>
> If someone wants me to prove it, I'll be more than happy to start
> removing/inserting disks on my system here at home to show exactly what
> happens (using ICH9xx with ahci.ko).  I would prove it as well with our
> production machines but I'd have to physically be in the co-lo to swap
> the disk.  :-)
>
> The OP only mentioned that he was concerned with device names changing
> if he swapped disks.  I have not seen hot-swapping (specifically
> removal of old disk, insertion of new disk) result in the device number
> increasing -- ever.

Reread the original post.  :)

The point of the post is "how do you keep device bus enumeration the
same across reboots".  Reboot is mentioned a couple of times in the
post.  :)

The OP wants to know how to populate X out of Y ports on a controller,
and have the numbering remain the same across reboots, when
adding/removing drives.

Without using hint.* entries in /boot/loader.conf, you can't.  AFAIK,
there's not CAM-based equivalent to ATA_STATIC_NUMBERING in the kernel
(or whatever that option is called).

Thus, you have to resort to labelling the drives/partitions in one
fashion or another, so that no matter what the underlying device node
is, the "name" of the drive never changes.

-- 
Freddie Cash
fjwcash at gmail.com