iSCSI autosense and ACA

[Dennis Young <dyoung@rhapsodynetworks.com>]

Hi,
I would appreciate if someone could clarify why ACA is
needed if autosense is mandatory?
Thanks,
Dennis

---

Section 3.3.3 and 7.2 of rev 06 are copied here for reference:

  3.3 iSCSI Port Mode Page 
    
     The following outlines the iSCSI Port mode page:
     ...
  3.3.2 Enable ACA (A) 
    
     When this field is set to 1 the target is mandated to enter ACA state 
     as specified.  When set to 0 the target shall not enter ACA state. 
     This field can also be set by a text-mode key=value pair (EnableACA).

  7.2 Autosense and Auto Contingent Allegiance (ACA) 
    
     Autosense refers to the automatic return of sense data to the 
     initiator in case a command did not complete successfully. iSCSI 
     mandates support for autosense. 
    
     ACA helps preserve ordered command execution in presence of errors. 
     As iSCSI can have many commands in-flight between initiator and 
     target iSCSI mandates support for ACA.