RFC: ATA to CAM integration patch
Scott Long
scottl at samsco.org
Sat Jun 27 14:42:59 UTC 2009
Kamigishi Rei wrote:
> Hello, hope you're having a nice day,
>
> Ulrich Spörlein wrote:
>> I, personally, think this is not very good idea. People are used to
>> CAM-devices getting enumerated as da0, da1, etc. All the documentation
>> talks about ad0 for ATA and da0 (plus camcontrol) for SCSI, USB,
>> Firewire devices. We also have fd0 and cd0 and should stick to
>> two-letter-plus-number codes. So either make them all ad0 or da0. I'd
>> vote for the latter, as that is what Linux is doing (more or less) and
>> people are already familiar with USB drives or new SATA drives showing
>> up as "SCSI drives, so they get the SCSI names".
>>
> This poses the question of daXX enumeration order. I've already had some
> 'fun' with an IBM server which has an LVD/320 SCSI controller. While the
> controller's bus was enumerated properly, somehow if you attach an USB
> mass storage device before the system boot that said mass storage could
> suddenly appear earlier than one of the SCSI disks (that was on
> 7.0-RELEASE) thus breaking the boot process sometimes (when it appeared
> as da0).
>
CAM allows you to statically set the enumeration order via hints in
either the kernel config file or in /boot/loader.conf. /sys/conf/NOTES
contains information and examples of this.
Scott
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