UAS questions

Curtis Stevens curtis.stevens at
Fri Mar 27 13:17:40 PDT 2009

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		Please send your comments in the form of an .FDF or a .PDF.
I will be using these to create a doc with all the comments I receive.	I
have prepared UAS for commenting with Acrobat Reader 8 or above.
		Regarding Max Packet Size, this is a field from USB 2.0 and
USB 3.0 which indicates the maximum USB packet which can be transferred
between the initiator and the target.  For USB 2.0, this is documented as
512 bytes, for USB 3.0 this is 1,024 bytes.
		There is no data IU.  Instead, we have dedicated  pipes for
transferring data.  These pipes separate the data from the command and
status which use a separate pair of pipes.
Curtis E. Stevens
Sr. Staff  Engr - Standards & Features Technology
20511 Lake Forest Drive #A 113-F
Lake Forest, California 92630
Phone: 949-672-7933
Cell: 949-307-5050
E-Mail: Curtis.Stevens at  
From: owner-t10 at [mailto:owner-t10 at] On Behalf Of Kevin D Butt
Sent: Thursday, March 26, 2009 3:33 PM
To: Curtis Stevens
Cc: t10 at
Subject: UAS questions
In what format do you desire letter ballot comments?  Simple in text like we
submit officially or some other way? 
One of my reviewers was confused about the max packet size.  I assume that
max packet size is the maximum size of a single packet but that a single
SCSI data transfer may be composed of multiple packets.  Is there a limit on
the maximum SCSI data transfer size (e.g., logical block size)?  I cannot
find anyplace that defines that a SCSI Block may be transferred in multiple
data packets. 
I see no definition of a Data Information Unit.  I cannot figure out how we
would indicate that we are sending data in the packet when there is no Data
Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at

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