ADC-2: Logical Unit mode pages "ENABLE" bit
Kevin D Butt
kdbutt at us.ibm.com
Wed Sep 12 15:06:10 PDT 2007
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Clause 188.8.131.52.3 of ADC-2r8 has the following sentence.
An ENABLE bit set to zero specifies that the DT device primary port(s)
associated with the SMC logical unit shall not respond to commands and
task management requests received on the DT device primary port(s)
Clause 184.108.40.206.3 SMC logical unit descriptor format is describing Logical
units and how they are configured. It seems to me that the enable bit
should be related to how the SMC logical unit behaves and not how a port
behaves. In my thinking the enable bit should be enabling the logical
unit or disabling it. The correct response to a command directed at it
should be to return a 5/2500 ILLEGAL REQUEST LOGICAL UNIT NOT SUPPORTED.
As ADC-2 reads it says the port shall not respond to any commands or task
management functions received on the device primary port(s). So I cannot
respond to anything directed at LUN 0 either.
If you make a stretch and say that "the DT device primary port(s)
associated with the SMC logical unit" means that it only applies to the
port when the LUN field specifies the SMC logical unit, then we have the
behavior that the device drops all requests that are either commands or
task management requests and makes no response to the host. This seems
weird to have a port respond to transport specific communications (e.g.,
selection, LIP, etc) and to requests targeted at other LUNs but to go
silent and not respond to those directed at a specific LUN. I think the
HBA will think the device has disappeared or has hung.
This is the same wording for the other LUN pages also.
Am I missing something?
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 at us.ibm.com
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