Save Data Pointer (02H); Restore Pointers (03H); Disconnect (04H); Initiator Detected Error (05H) - IBM IC35L036UWDY10 - Ultrastar 36.7 GB Hard Drive Specifications

! HOLD_MCS (Hold Margin Control Settings) is used to negotiate if any margin control settings which
has been set with the margin control subpage of the port control mode page is retained.
! QAS_REQ (Quick Arbitration and Selection Enable Request) is used to negotiate if QAS is enabled.
The drive supports QAS when IU_REQ is negotiated to be effective.
! DT_REQ (DT Clocking Enable Request) is used to negotiate if DT DATA phase is enabled. The drive
supports DT_REQ.
! IU_REQ (Information Unit Enable Request) is used to negotiate if information unit transfer is enabled.
The drive supports IU_REQ.

10.1.5 SAVE DATA POINTER (02h)

This message is sent from the drive to direct the initiator to copy the active data pointer to the saved data
pointer. The SAVE DATA POINTER message is only sent if the initiator has previously indicated the ability
to accommodate disconnection and reconnection via the IDENTIFY message.
The drive will send the SAVE DATA POINTER message to the initiator prior to sending a DISCONNECT
message to the initiator if a DATA phase has occurred and another data phase is required to successfully
complete the command.

10.1.6 RESTORE POINTERS (03h)

This message is sent from the drive to direct an initiator to copy the most recently saved pointers to the
corresponding command, data, and status pointers. Command and status pointers should be restored
to the beginning of the present command and status areas. The data pointer should be restored to the
value at the beginning of the data area in the absence of a SAVE DATA POINTER message or to the
value at the point at which the last SAVE DATA POINTER message occurred. Also see Section 10.4,
"SCSI Bus Related Error Handling Protocol" on page 191.

10.1.7 DISCONNECT (04h)

This message is sent from the drive to inform an initiator that the present connection is going to be broken.
A later reconnect will be required in order to complete the current command. The disconnection serves to
free the SCSI bus while the drive performs a relatively long operation that does not require the bus. These
messages are sent only if the initiator previously indicated (via the IDENTIFY message) the ability to
accommodate disconnection and reconnection.
The DISCONNECT message may also be sent from the initiator to the drive to disconnect from the SCSI
bus. The drive does not support the DISCONNECT message from the initiator. And it always responds by
sending MESSAGE REJECT message to the initiator.

10.1.8 INITIATOR DETECTED ERROR (05h)

This message is sent from an initiator to inform the drive that an error has been detected that does not
preclude the drive from retrying the previous COMMAND, DATA, STATUS and MESSAGE IN phase. The
source of the error may be either related to previous activities on the SCSI bus or may be internal to the
initiator and unrelated to any previous SCSI bus activity
If the initiator intends to send this message, the initiator must assert the ATN signal prior to its release of
ACK for the last byte transferred in the information phase that is to be retried. This provides an interlock so
the drive can determine which information phase to retry.
After receiving this message, the drive may retry the previous phase by sending a RESTORE POINTERS
message to the initiator and then repeating the previous COMMAND, DATA, or STATUS phase.
After receiving this message the drive may retry the MESSAGE IN phase by switching to the MESSAGE
IN phase with asserting REQ and repeating the previous MESSAGE IN phase.
Ultrastar 146Z10 hard disk drive specifications
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