LUN creation on an IBM Storage DS8000 can be delayed recognized by the server

(Doc ID 2019196.1)

Last updated on MARCH 07, 2018

Applies to:

SPARC T5-4 - Version All Versions to All Versions [Release All Releases]
Solaris Operating System - Version 8 6/00 U1 and later
Information in this document applies to any platform.
The in depth scsi protocol knowledge is provided from Peter Davies

IBM has acknowledged that their storage does not follow
the spec with regards to sending 'unit attention'/'report
luns has changed', but have now generated a change request
to get this implemented into the future array firmware


When a new lun is mapped, or unmapped, on the storage,
the host is unaware there has been any configuration
change, unless the storage communicates that change


The standard way of 'announcing' this change is for
the storage to raise a 'check condition' for the
very next IO, to any already existing lun for the
affected target.

The host will react to this check condition by
reading associated sense data from the storage
for the check condition.

The sense data returned will be the following:

The sense key will be set to 'Unit Attention'

The ASC/ASCQ ( additional sense code and additional
sense code qualifier ) will be set to "Reported luns
data has changed"

As soon as the host reads this sense data, it issues
a "Report Luns" scsi command to the storage target,
and the target responds with a list of currently
mapped luns.

If this list contains a new lun number, that new
lun will then be configured


If there is no traffic on any LUN on an IBM DS8000,

the storage will not communicates that change


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