Re: generating a Linux WWN?

Jeff Garzik
2007-10-03T16:16:41Z

Douglas Gilbert wrote:
> Jeff Garzik wrote:
>> Luben Tuikov wrote:
>>> --- Jeff Garzik <jeff@garzik.org> wrote:
>>>> The admin will have the option to auto-generate a WWN, should they so
>>>> desire.
>>> What does that mean? "auto-generate"? By whom?
>> The admin tells the kernel module to auto-generate a WWN, and the kernel
>> module happily obliges.
>>
>> The generation algorithm is whatever makes people happy. I would
>> probably pick a fixed prefix like 0x6C 0x69 0x63 ("lin"), something that
>> doesn't conflict with IEEE org ids for a long time to come. Then,
>> get_random_bytes() or hash some useful machine characteristics for the
>> rest of the bytes.
>>
>>
>>> What if they don't "auto-generate" (whatever that means)?
>> Well, you either have a WWN or you don't :)
>
> Jeff,
> It is not quite black and white. As I tried to point
> out, when a SAS HBA is run in target mode, there is
> a good chance there aren't _enough_ unique SAS addresses
> allocated by the manufacturer.
>
> There should be naa-5 addresses for the ports, it is
> the target device address and 0 or more lu addresses that
> may need to be generated.

Oh quite agreed ... I was definitely talking about the initiator.

The thread has come full circle again :) I would definitely like to
figure out a standard way to generate new SAS addresses.

Jeff