Re: SAS scsibus target numbering

[Matt Thomas <matt%3am-software.com@localhost>]

On Jul 26, 2012, at 9:07 PM, Alistair Crooks wrote:

> On Fri, Jul 27, 2012 at 07:35:19AM +1000, matthew green wrote:
>> 
>>> I have a (mpt) SAS with seven discs connected.
>>> The discs attach as sd0..sd6, but the SCSI target numbers are 0..5 and 7.
>>> It appears to me that someone is skippig ID 6 for the controller.
>>> It doesn't hurt too much, but it took me a while to find out why detaching 
>>> targets 2, 3, 4 and 5 worked and 6 didn't (of course, 7 worked).
>>> 
>>> Is there a reason for this behaviour?
>> 
>> it's usual for the SCSI HBA to assign a targetID for itself.
>> 
>> besides having to use a different number, is there any real reason
>> you want to change them?  perhaps a better solution would be to
>> patch scsictl such that we can detach via autoconf name as well
>> as scsi addresses.  maybe we should do this anyway..
> 
> Depending on LSI firmware (I think), the LSI may re-number disks
> depending on how they present themselves, uuid, etc.  Some people like
> this persistence (mainly Winders users, I imagine), it causes problems
> for others.
> 
> To get around this, at work I used lsiutil to clear the NVRAM
> settings.  Otherwise, switching out all the LSI-attached disks in one
> of the Open Connect Appliances made the drives present themselves as
> da33 to da64, rather than da1 to da32 - under FreeBSD, obviously.

Of course, if NetBSD supported non-integer locators, then we could use
WWNs (World Wide Names) as locators since really the bus is one
possible path to the drive (think fibre-channel).