[T10] Comments on 19-066r0 SPC-5 SBC-4 Add rules for multi-LUN command interlock
Kevin D Butt
kdbutt at us.ibm.com
Mon Jun 10 11:32:44 PDT 2019
It seems to me that your proposal changes the behavior 11b of the MLU
field such that it is not backward compatible and removes an option that
is currently available -- and perhaps is relied on. There will no longer
be a way to affect all logical units with a single command. Now, each and
every logical unit must be connected and communicating before the command
can process. This includes the SANITIZE command. Now, in a critical
situation where a device needs sanitized in a hurry, there are additional
requirements that might not be met before the sanitize can occur.
The entire meaning of code 10b is changed.
This command affects more than one but not all logical units contained in
this SCSI target device. This command operates on only this logical unit
but may impact the performance of other logical units attached to this
SCSI target device while this command is in progress.
The new meaning relates solely to performance, while the original has no
specification of what the effects might be.
Also, I am not sure the replacement of "affects" with "operates on" works
as intended. There is a subtle difference which may cause issues.
Take "This command affects operates on only this logical unit. " This
states that the command only operates on this logical unit, but it makes
no statement about whether or not it might cause effects to be noticed on
other logical units.
Aside from the obvious changes, Code 11b changes from "logical units
contained in" to "logical units attached to ". Now the SCSI Target device
must become a copy manager and forward that command to other logical units
in other SCSI Target devices to which it may be attached.
SPC-5 SBC-4 Add rules for multi-LUN command interlock
(by: Gerald Houlder)
T10/19-066r0 Uploaded: 2019/06/04 135997 bytes
Kevin D. Butt
SCSI Architect, Tape Firmware, Data Retention Infrastructure
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at us.ibm.com
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