Re: [PATCH] libmultipath: Handle SCSI-2 style vpd page 0x83 descriptors

[Benjamin Marzinski <bmarzins@redhat.com>]

On Tue, Apr 07, 2026 at 11:14:34AM +0200, Xose Vazquez Perez wrote:
> On 3/27/26 4:41 AM, Benjamin Marzinski wrote:
> 
> > Some older SCSI devices return a SCSI-2 style vpd page 0x83, instead of
> > a SPC-2/3 format one. The SCSI-2 page 83 format returns an IEEE WWN in
> > binary encoded hexi-decimal in the 16 bytes following the initial
> > 4-byte page 83 reply header.
> > 
> > Check the 7th byte of the vpd page 83 buffer to determine whether this
> > is a SCSI-2 or SPC-2/3 confomant one. Byte 7 is the 3rd byte of first
> > Identification descriptor in a SPC-2/3 confromant vpd page 83. This is a
> > reserved field, and is guaranteed to be 0. If it is not zero, then it is
> > likely the 3rd byte of a SCSI-2 Identifier (The first 3 bytes of the ID
> > are the Organizationally Unique Identifier). Both the sg_inq and scsi_id
> > commands handle vpd page 83 this way. To make sure that the WWID which
> > multipath reads directly from the device matches, it should handle this
> > format as well.
> Out of curiosity. Did you run into a specific old device that triggered this,
> or was this found by code inspection ?

It was through code inspection.

-Ben