Retain Training Correction

Bill Galloway BillG at
Thu Nov 9 19:39:46 PST 2000

* From the T10 Reflector (t10 at, posted by:
* "Bill Galloway" <BillG at>
Here is the bulk of 00-414r0 (to be posted soon).  I wanted to send it
out over the reflector to get any comments.

The current way that training information is retained has a problem if
a SCSI device changes roles between initiator and target. While a SCSI
device is an initiator, the training pattern is used to deskew data
relative to the REQ signal.  These saved training values are not
meaningful if the SCSI device changes roles to a target. For targets,
the training pattern is used to deskew the data relative to the ACK
signal. The problem can be fixed by adding at the following (last)
sentence to Training pattern overview


If the retain training information is enabled a training pattern shall be
transferred at the start of the first DT data phase for each data transfer
direction after the retain training information is enabled. The SCSI
device shall save training configuration values for each I_T nexus that
has negotiated to retain training information. The SCSI device shall use
the saved training configuration values for all paced transfers. The target
may retrain an I_T nexus if it determines the training configuration values
are invalid, without having to renegotiate the retain training information
protocol option. NEW>>The target shall retrain if the saved training
configuration values were saved while the SCSI device was an initiator.<<NEW

Bill Galloway
BREA Technologies, Inc.
P: (281) 530-3063
F: (281) 988-0358
BillG at

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