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Re: [dm-devel] Linux utility to determine WWN from a LUN number

Hi Chip,

Chip Coldwell wrote:
> On Thu, 13 Mar 2008, lemons_terry emc com wrote:
>> Sorry, but doesn't scsi_id only return what it finds in SCSI VPD pages
>> 80 or 83?  Not all devices provide a WWN in VPD page 83.
> It's quite a bit more complicated than that.  If a WWN exists on VPD
> pages 80 or 83, scsi_id will return that; otherwise it will synthesize
> a serial number.
> Doug Gilbert and I have exchange some correspondence on the subject of
> unifying his lsscsi (and possibly sg3_utils), my scsitool and the udev
> scsi_id utility.  At the moment, all of these are drawn from different
> code bases.  Doug chose to design lsscsi to use only sysfs information
> because he wanted it to be runnable as a non-privileged process.
> That's both good and bad: sysfs is shifting sand to build a foundation
> on, and so far there is no standard place in sysfs to retrieve a WWN.
> Both scsi_id and sg3_utils use SG_IO to do a VPD 0x80/0x83 INQUIRY.
I'd be more than happy to move the scsi_id program out of the udev
codebase and merge it with sg3_utils. Or, possibly better, would
be to have scsi_id use the libraries provided by sg3_utils.
scsi_id is just part of udev as it accidentally ended up there ...

IIRC we even hijacked that out of multipath-tools at one point.
And what's more, it's effectively orphaned as Patrick Mansfield
doesn't seem to work on SCSI things anymore. So moving scsi_id
to a better maintained base would indeed be a good idea.

BTW: what is the main reason for scsitool? Does it have features
which scsi_id and sg3_utils are missing?


Dr. Hannes Reinecke		      zSeries & Storage
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