[T10] ZAC back pressure on ZBC

Ralph Weber 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,

.Ralph


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