Unit Attention Condition - IBM Ultrastar 36LZX Specifications

11.1.5 Unit Attention Condition

The drive will generate a unit attention condition for each initiator whenever
Ÿ The drive has been reset. This includes Power On Reset, SCSI Bus Reset, SCSI BUS DEVICE
RESET message.
Ÿ The mode parameters in effect for this initiator have been changed by another initiator.
Ÿ The microcode has been changed. WRITE BUFFER command has been executed to download
microcode. In this case a unit attention condition is generated for all initiators except the one that
issued the command.
Ÿ Commands are cleared by another initiator. This condition is generated against the initiator that has
queued commands if
− Clear Queue Message is received.
− Contingent Allegiance Condition is cleared when QERR (in Mode Page 0A) is 1.
− DQue is set to 1 while queued command exist.
The unit attention condition persists for each initiator until that initiator clears the condition as described
in the following paragraphs.
If the drive receives a command from each initiator before reporting a CHECK CONDITION status for a
pending unit attention condition for that initiator, the response of the drive varies with the command as
follows:
INQUIRY
REQUEST SENSE
ALL OTHER
If the drive receives a command from each initiator after reporting a CHECK CONDITION status for a
pending unit attention condition for that initiator, the response varies with the command as follows:
REQUEST SENSE
ALL OTHER
The drive executes the command with GOOD status and preserves the unit
attention condition.
If the drive has an available pending sense data for the initiator, the drive sends
the pending sense data and preserves the unit attention condition for the
initiator. If the drive does not have an available pending sense data for the
initiator, the drive sends sense data for the unit attention condition and clears the
unit attention condition for the initiator.
The drive terminates the command with a CHECK CONDITION status and pre-
serves the unit attention condition.
The drive sends the sense data for a pending unit attention condition and returns
GOOD status. And the drive clears the unit attention condition for the initiator.
The drive executes the command with GOOD status and clears the unit attention
condition unless another unit attention condition exists. And then the sense data
for the unit attention condition is lost.
Ultrastar 36LZX hard disk drive specifications
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