Switchover to CAM ATA?

Alexander Motin mav at FreeBSD.org
Fri Apr 23 10:13:45 UTC 2010

Paul Wootton wrote:
> Alexander Motin wrote:
>> Can we do switchover now, or some more reasons preventing this?
> The only thing I miss about the old ATA layer was that I knew that a
> drive on a particular controller would always be assigned the same adX
> number, whether is was present at boot time, or added days later. This
> could get a little messy having ad2, ad4, ad12, ad20 and ad22, but at
> least if I added a new drive, it would always attach to say ad8.
> Can this be done on the new CAM ATA?

Binding to controller ports and device IDs can be managed for any CAM
device via device.hints as described in cam(4). This scheme is a
slightly more complicated (you have to explicitly define wanted
mapping), but more flexible. Previous one just inapplicable now. Modern
controllers (especially with Port Multipliers) could support different
(often big) number of devices per channel, making device list with
static numbering too sparse.

Alexander Motin

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