From the SCSI Bulletin Board System                  X3T9.2/90-67

Date: 10 Apr 90 10:52:11
From: Gene Milligan
To:   All Hosts
Subj: LOG SELECT

 
 
 
     Please  refer  to  Section  7.3.2  of  SCSI  Rev  10b.   The 
description  of  the disable save (DS) bit indicates  this  is  a 
statement of support by the target. 
 
     The  description  of the target save disable  (TSD)  bit  is 
partially  informative of support and explicitly controllable  by 
the host. In addition this description explicitly indicates  that 
the host also controls DS.
 
     We  can speculate on why the host may want to control  these 
bits.  An obvious reason could be that the host wanted  to  avoid 
any potential performance decrease from the overhead of the  save 
operation (if it assumed the save was statistically significant). 
But  if  that were the reason why insist that the target  give  a 
CHECK  CONDITION  for  both  set  to  one?  From  a   grammatical 
standpoint  I can see justification for giving a check  condition 
if  the  host  sets DS to one and TSD to zero  but  not  from  an 
engineering standpoint.
 
     What are the host oriented opinions?