To: dennis@hale-pohaku.com, t10@t10.org
Subject: Re: SSC-3 Tape Alert Flag 20h Question
From: Kevin D Butt <kdbutt@us.ibm.com>
Date: Mon, 13 Mar 2006 14:43:31 -0700
X-Message-Number: 6715
Formatted message: HTML-formatted message

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@us.ibm.com
http://www-03.ibm.com/servers/storage/ 
Dennis Painter <dennis@hale-pohaku.com> 
Sent by: owner-t10@t10.org
03/13/2006 12:32 PM
Please respond to
dennis
To
T10 Reflector <T10@t10.org>
cc
Subject
SSC-3 Tape Alert Flag 20h Question
* From the T10 Reflector (t10@t10.org), posted by:
* Dennis Painter <dennis@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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