SSC-3 Tape Alert Flag 20h Question

[Dennis Painter]

* From the T10 Reflector (t10 at t10.org), posted by:
* Dennis Painter <dennis at hale-pohaku.com>
*
Hello Kevin,
I understand what SSC says but am still left with my question:
"... how does this flag ever get reported to a host if it is deactivated
when the interface is working?"
It seems to me that without some change it can never be reported, but I
hope I am wrong and that someone can show how.
Thanks,
Dennis
Kevin D Butt wrote:
>
> Dennis,
>
> In our discussions of this TapeAlert in the SSC Working Group no
> company had any issues with this behavior. In fact this is how we
> interpreted SSC.   As TapeAlerts are defined in SSC,
> Each flag shall be cleared in the following circumstances:
> a) At drive power on;
> b) after the TapeAlert log page is read - note in multi-initiator
> environments the TapeAlert flags shall be cleared on a per-initiator
> basis such that set flags are still visible to other initiators;
> <<<< c) when the specified corrective action has been taken (such as
> using a cleaning cartridge); >>>>
> d) on SCSI bus reset or bus device reset message; or
> e) on LOG SELECT reset.
>
> The whole TapeAlert concept has not been well defined in SSC.  We have
> been making attempts to define it more concisely and to also add a new
> method of reporting tapeAlerts that are state based and not reset on
> reporting. (ala ADC)
>
> Thanks,
>
> Kevin D. Butt
> SCSI & Fibre Channel Architect, Tape Firmware
> MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
> Tel: 520-799-2869 / 520-799-5280
> Fax: 520-799-2723 (T/L:321)
> Email address: kdbutt at us.ibm.com
> http://www-03.ibm.com/servers/storage/
>
>
> Dennis Painter
				    To T10 Reflector <T10 at t10.org>
  <dennis at hale-pohaku.com>
  Sent by: owner-t10 at t10.org	    cc
				       SSC-3 Tape Alert Flag 20h
  03/13/2006 12:32 PM	       Subject Question
   Please respond to
	 dennis
>
>
>
> * From the T10 Reflector (t10 at t10.org), posted by:
> * Dennis Painter <dennis at hale-pohaku.com>
> *
> I note that ssc3r04 now defines a deactivation condition for the
> Interface flag, 20h.
>
> Deactivation condition for flag 20h being "After interface returns to
> operation"
>
> My question is how does this flag ever get reported to a host if it is
>
> deactivated when the interface is working?
>
> For example with a parallel interface if a parity error is detected by
>
> the target I would expect the target to activate the flag. If the next
>
> interface transaction has no error I would expect the target,
> following
> the deactivation condition specified, to deactivate the flag. Since
> the
> flag is now deactivated a poll of the log page would never show the
> flag
> was ever set. If this is the case what's the point of having flag 20h?
>
> >From a purely historical perspective I recall this being discussed at
> a
> Tape Alert working group before Tape Alert was added to SSC. At that
> discussion it was agreed that this flag should be "sticky" and persist
>
> until reported to the host. To the best of my knowledge that
> discussion
> was never written into the pre SSC Tape Alert documents. I do know
> that
> this "sticky" attribute has been used in implementation of Tape Alert
> but now that the standard specifies a deactivation condition that
> implementation will need to change to be compliant with SSC-3.
>
> Thanks for any clarification on this item,
>
> Dennis Painter
>
>
>
>
>
>
>
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