When should Mode parameter header (not) be returned?

Gerry Houlder gerry.houlder at seagate.com
Wed Aug 15 06:29:04 PDT 2012

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When the target returns CHECK CONDITION status to complain about something
illegal in the CDB, then no data is returned, only the status information.
With SAS 9which has autosense feature) the sense data is returned as part
of the status frame.
On Wed, Aug 15, 2012 at 2:40 AM, Eric Agan <eric at elegantinvention.com>wrote:
> * From the T10 Reflector (t10 at t10.org), posted by:
> * Eric Agan <eric at elegantinvention.com>
> *
> Hi,
> Should Mode Sense(6) and Mode Sense(10) return the appropriate Mode
> parameter header even if an unsupported Page or Subpage was requested?
> SPC-3 states:
> "An application client may request any one or all of the supported
> mode pages from the device server. If an application
> client issues a MODE SENSE command with a page code or subpage code
> value not implemented by the
> logical unit, the command shall be terminated with CHECK CONDITION
> status, with the sense key set to ILLEGAL
> REQUEST, and the additional sense code set to INVALID FIELD IN CDB."
> ...but doesn't seem to clarify whether the header should be returned
> anyway or not.
> What about other errors such as requesting Changeable Values when the
> logic unit doesn't implement them? SPC-3 dictates the same response as
> above for that scenario.
> My assumption has been to always return the header.
> Thanks,
> Eric Agan
> Elegant Invention
> *
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