RESERVE(6)/RELEASE(6) again, or the serial interpretations of SCSI-3.

scheible at scheible at
Mon Jun 17 14:25:33 PDT 1996

* From the SCSI Reflector, posted by:
* scheible at VNET.IBM.COM
In response to my RESERVE(6)/RELEASE(6) note, Bill Dallas wrote...

> A solution would be to obsolete RESERVE and
> RELEASE (6) for SCSI-3 and mandate the 10 byte
> versions for SCSI-3 devices.  This solution is
> only a part solution since it does not address
> those devices that have soft addressing
> (FCP, SCAM, etc).
> Persistent Reserve could be a solution for SCSI-3
> devices where the RESERVE and RELEASE commands are
> obsoleted for SCSI-3 and Persistent Reserve mandated.
> From my view point any solution that does not require
> the peripheral drivers to have specific knowledge
> of an inter-connect is good.

   To avoid transport layer specific items in the device drivers, I
assume that FCP would like to use PERSISTENT RESERVE/RELEASE.  However,
I assume this is a big change for SCAM.  Also, since SSA is a "slight"
modification over parallel SCSI, this is more code for SSA.  I cannot
judge the impact to SBP.

   I see that we need to change the mandates of SCSI-3 that do not
work for soft addressing schemes (FCP, SCAM), nor for large address
schemes (wide parallel SCSI, FCP, SBP. S3P).  It is an impact to use
for soft addressing (SCAM, FCP), transport layer functions for SBP
(although they could be hidden), and RESERVE(10)/RELEASE(10) for S3P
and makes the device driver people roll over in their graves (after it
kills them).

   Maybe this is a topic for the Serial Concerns meeting next month
during the X3T10 plenary week?

Any thoughts?

John Scheible
scheible at

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