SSC-3 Tape Alert Flag 20h Question
dennis at hale-pohaku.com
Mon Mar 13 11:32:57 PST 2006
* 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
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,
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