IBM Ultrastar 36LZX Specifications page 212

Ÿ Queue Full Status is returned if
- the command would otherwise be queued (according to the rules described above) but the
command queue is full and all slots are utilized, or
- the command would otherwise be queued (according to the rules described above) but all of the
available command queue slots not reserved for use by another initiator are utilized, or
- Tagged Queuing is enabled (DQue = 0) and a Format Unit command was previously queued but
has not yet begun execution, or
- Tagged Queuing is enabled (DQue = 0) and a Start Unit command was previously queued but
has not yet begun execution.
Ÿ Busy Status is returned if
- Tagged Queuing is disabled (DQue = 1) and a Format Unit command was previously queued but
has not yet begun execution, or
- Tagged Queuing is disabled (DQue = 1) and a Start Unit command was previously queued but
has not yet begun execution, or
- the command would otherwise be queued (according to the rules described above) but discon-
nection is not allowed for the current I/O process.
If a command is queued, command execution may still be prevented at a later time when the command
is dequeued to become an active I/O process. This occurs if command execution is prevented by an-
other internal Target condition listed in 11.1.1, "Priority of SCSI Status Byte Reporting" at the time the
command is dequeued.
Ultrastar 36LZX hard disk drive specifications
212