12-425r6 Command Deadlines (Command Deadline Descriptor Issue)

Kevin D Butt kdbutt at us.ibm.com
Mon Aug 5 10:45:13 PDT 2013

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I reviewed 12-425r6 and have found the following issue.
The Command Deadline Time mode page (8.7.3)  provides a 4-byte descriptor 
for Command deadline time which is defined as being in units of 
microseconds.  If this mode page is in SPC-5, then it should provide 
sufficient time for all command set standards (e.g., SSC).  A 4-byte 
deadline time of microseconds provides for a maximum of 2^32 
(4,294,967,296) microseconds which is less than 1.2 hours.  SSC devices 
have commands that can take up to 6 hours.  This duration often grows with 
tape length and density.  As such, I see this mode page as being too 
limited to be able to be used for some SSC commands.
This mode page either belongs in SBC or the descriptor needs to be 
expanded to provide for use by SSC devices.
Kevin D. Butt
SCSI Architect, Tape Firmware, T10 Standards
Data Protection & Retention
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at us.ibm.com

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