HP Surestore 28/48-Slot with DLT7000 Digital Linear Tape SCSI-2 Drive and SCSI - Page 40

SCSI Command Overview Library Control Commands Unit Attention Condition For each initiator, a unit attention condition for a logical unit begins for the following: • Power on • Bus Reset • Bus Device Reset • Tape Loaded • Micro Code Change • Inquiry Data Change • Mode Select Data Change • Mailslot Accessed • Log Parameters Changed • Reservations Preempted • Operating Conditions Changed The unit attention condition persists for each initiator until it issues a command to the logical unit (other than Request Sense or Inquiry) for which the target reports a CHECK CONDITION status. If the next command from that initiator to the logical unit (following the CHECK CONDITION status) is Request Sense, the Unit Attention sense key is returned; otherwise it is lost. If an Inquiry Command is received from an initiator with a pending unit attention condition (before the target reports CHECK CONDITION status), the target performs the Inquiry Command and does not clear the unit attention. If a Request Sense Command is received from an initiator with a pending unit attention condition (before the target reports a CHECK CONDITION status), the target does the following: • Discards any pending sense data • Reports a Unit Attention sense key • Clears the unit attention condition for that initiator 1- 16 Chapter 1