[T10] ZAC back pressure on ZBC
roweber at ieee.org
Mon Nov 16 14:10:29 PST 2015
During today's ZAC call, the second to last paragraph in 5.5 (OPEN ZONE
command) was discussed at length. The text in question is as follows.
"For a host managed zoned block device, if the ALL bit is set to one and
the number of zones with a Zone Condition of EXPLICIT OPEN plus the
number of zones with a Zone Condition of CLOSED is greater than the
maximum number of open sequential write required zones, then the device
server shall terminate the command with CHECK CONDITION status, with
sense key set to ABORTED COMMAND and the additional sense code set to
INSUFFICIENT ZONE RESOURCES."
Is simply retrying a OPEN ZONE (ALL) command likely to produce a
successful result, which is what the ABORTED COMMAND sense key implies?
Absent changing some zones to EMPTY or FULL before retrying, the answer
to the above question appears to be an emphatic **NO**.
As a result, several of those present on the call felt ILLEGAL REQUEST
would be a better sense key than the one specified by ZAC and ZBC.
Notwithstanding the potential Houlderization that requesting a change to
ILLEGAL REQUEST entails, those on the ZAC call agreed that ZAC would be
best served by making the "adjustment" ... which means more work for the
ZBC editor (if this stuff rolls downhill in the usual manner).
All the best,
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