LUICLR bit in Extended Inquiry Data

Kevin D Butt kdbutt at us.ibm.com
Fri Sep 3 16:12:49 PDT 2010


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1009030_f.htm">HTML-formatted message</a>

In SPC-4r26, Extended Inquiry Data VPD Page, I find the following bit 
description.
<<A logical unit I_T nexus clear (LUICLR) bit set to one indicates the 
SCSI target device clears any unit attention
condition with an additional sense code of REPORTED LUNS DATA HAS CHANGED 
in each logical unit accessible
to an I_T nexus after reporting the unit attention condition for any 
logical unit over that I_T nexus (see
SAM-4). An LUICLR bit set to zero indicates the SCSI target device clears 
unit attention conditions according to a
previous version of this standard. The LUICLR bit shall be set to one.>>
I read it several times and it did not make sense to me.  After a good bit 
of scrutiny, I determined that it must mean that if the REPORTED LUNS DATA 
HAS CHANGED UA is reported by LUN A over I_T nexus (2), then all LUNs 
accessible over I_T nexus (2) also clear the REPORTED LUNS DATA HAS 
CHANGED UA.  However, it is possible that I am misinterpreting this 
requirement.  If I have interpreted this correctly, wouldn't it be better 
to say:
A logical unit I_T nexus clear (LUICLR) bit set to one indicates the SCSI 
target device clears any unit attention condition with an additional sense 
code of REPORTED LUNS DATA HAS CHANGED in each logical unit accessible to 
an I_T nexus after reporting the <<REPORTED LUNS DATA HAS CHANGED>> unit 
attention condition for any logical unit over that same I_T nexus (see 
SAM-4). An LUICLR bit set to zero indicates the SCSI target device clears 
unit attention conditions according to a previous version of this 
standard. The LUICLR bit shall be set to one.
Thanks,
Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at us.ibm.com



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