Soft Write Protect in SPC

Thu Jan 25 21:16:55 PST 1996

* From the SCSI Reflector, posted by:

If we add a Soft Write Protect field in the SPC we could have three separate 
documents which use this field. The SPC, SSC, and SMC could/would all have 
SWP.  Potentially, a medium changer device would have to keep track of the 
SWP bit to be in compliance with all three documents. The obvious question is 
which document would have precedence?  What happens in a multi-initiator 
situation and we have SWP support in three different pages?  What is the 
state of the SWP bit after a media change or other Unit Attention condition?
What are the effects if the Mode Select cdb was sent with save pages set?

If we keep the Soft Write Protect field in any of the documents then I would 
like to suggest a change in the additional sense code fields in SPC. If this 
is not already done I would suggest adding a code for the Soft Write Protect, 
such as, "27 01 - Write Protected, set by host".  The present code for write 
protect could be changed to,"27 00 - Write Protected, set by physical switch".

Doug Pirie
Address: Doug.Pirie at

More information about the T10 mailing list