persistent target id's for FC, how?

So ... don't FC devices come up as cxtydz? But FC devices don't have
scsi ids, they have WWNs. So how do WWNs get mapped to targets
persistently?

I'm asking about FC but really I want to get a hint about SAS, which
is similar. I noticed on x64, in the BIOS (rather, from lsiutil in
Solaris) for my LSI SAS card that there are a lot of persistent
mappings, but I can only trace one of them to a physical device, which
is the attached JBOD enclosure itself.

In OBP on sparc, probe-scsi-all returns a different ordering of SAS
devices (and assigned scsi targets) depending on how long I let things
settle between power cycles. I'm worried that if I ever do get this
SAS card working on sparc, targets won't be stable. Not a showstopper
for me since I'll be using zfs and it's my understanding that zfs
(like SVM) will track the drive if it changes scsi targets, but still
enough of a problem that I want to know how this works.

I imagine that for FC, whatever 'cfgadm' consults maintains persistent
WWN->scsi target mappings, much like controller numbers are persistent
based on when the /dev link is created. Maybe this is just a symlink
to /devices node which is named after the WWN, for FC. But for SAS,
AFAICT, Solaris does not maintain SASAddresses.

-frank

Frank Cusack <> wrote:
> So ... don't FC devices come up as cxtydz? But FC devices don't have
> scsi ids, they have WWNs. So how do WWNs get mapped to targets
> persistently?

By the FC driver. Different ones do different things.

For legacy (sd style) drivers, there's usually an option to map a WWN to
a target explicitly (and thus persistently).

The Solaris leadville stack simply sticks the full WWN as the target so
it's always persistent.

> I'm asking about FC but really I want to get a hint about SAS, which
> is similar. I noticed on x64, in the BIOS (rather, from lsiutil in
> Solaris) for my LSI SAS card that there are a lot of persistent
> mappings, but I can only trace one of them to a physical device, which
> is the attached JBOD enclosure itself.

Hmm. Pass. I haven't played with SAS yet at all.

Does a SAS device have a persistent identity (like a normal SCSI or WWN
address?) If so, I would hope that the driver would be able to
reference it in some manner.

--
Darren Dunham
Senior Technical Consultant TAOS http://www.taos.com/
Got some Dr Pepper? San Francisco, CA bay area
< This line left intentionally blank to confuse you. >

On Wed, 23 Aug 2006 23:30:26 GMT Darren Dunham <> wrote:
> Does a SAS device have a persistent identity (like a normal SCSI or WWN
> address?) If so, I would hope that the driver would be able to
> reference it in some manner.

Yes, the SASAddress.

-frank