hd numbering in 9.0beta1
yanegomi at gmail.com
Mon Aug 29 07:58:54 UTC 2011
On Mon, 29 Aug 2011, Roger Genre wrote:
> Hi everybody,
> I would point out a problem related with the new way, coming in 9.0, to hard
> disks numbering.
> As far I remember (5.0 ?), hardware detection of H.D.'s at O.S. boot-up
> numbered every channel potentially able to attach a disk to, and tagged the
> disks really attached with the number of his control channel; the sequence
> (from lowers to highers numbers) begins with scsi or scsi-like (e-sata, usb,
> fire-wire,...) controllers and ends with the controllers directly depending
> from the chipset (sata at this time).
> Such strategy allows to attach easily a new mass-storage device without
> modifying the disks numbering and thus the relevant fstab files.
> 9.0beta1 use a different numbering strategy,(with a similar sequence in
> harware detection) tagging succesively detected disks with adjacent numbers.
The best way I can put it has already been noted in the archives several
I don't have the corresponding commits right now, but I could dig them up
as they spawned a large discussion thread as well.
The basic gist is that several folks agreed that:
1. GEOM/UFS labels were the only way to go.
2. There are some caveats to using GEOM labels that discourages use as a
means of deterministically determining mountpoints.
3. A compatibility shim was added for ata -> atacam transitioning; see
kern.cam.ada.legacy_aliases in /sys/cam/ata/ata_da.c
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