Seagate Ultra 160, Ultra 320 manual Reset events, Asynchronous condition recovery

The effect of the hard reset on tasks that have not completed, SCSI device reservations, and SCSI device operating modes is defined in the SCSI Architecture Model-4 standard.

Any SCSI device that detects a hard reset shall also set its transfer agreement to the default transfer agree- ment.

5.4Reset events

When a SCSI device detects a reset event it shall initiate hard reset.

5.4.1Bus reset event

When a SCSI device detects a bus reset condition by detecting RST true for a reset delay, it shall cause a reset event. In response to a bus reset event, a SCSI target port shall create a unit attention condition for all ini- tiators. The sense key shall be set to Unit Attention with the additional sense code set to either SCSI Bus Reset Occurred or Power On, Reset, or Bus Device Reset Occurred.

5.4.2Power on reset event

When a SCSI device is powered on, it shall cause a reset event. In response to a power on reset event, the tar- get shall create a unit attention condition for all initiators. The sense key shall be set to Unit Attention with the additional sense code set to either Power On Occurred or Power On, Reset, or Bus Device Reset Occurred.

5.4.3Target reset event

When a SCSI device successfully receives a SCSI target port Reset message, it shall cause a reset event. In response to a SCSI target port reset event, the SCSI target shall create a unit attention condition for all SCSI initiator ports. The sense key shall be set to Unit Attention with the additional sense code set to either Bus Device Reset Function Occurred or Power On, Reset, or Bus Device Reset Occurred.

5.4.4Transceiver mode change reset event

When a SCSI device that contains multimode transceivers detects a transceiver mode change from LVD mode to MSE mode it shall cause a reset event. In response to the transceiver mode change reset event, a SCSI tar- get port shall create a unit attention condition for all initiators. The sense key shall be set to Unit Attention, and the additional sense code set to Transceiver Mode Changed to Single-ended.

When a SCSI device that contains multimode transceivers detects a transceiver mode change from MSE mode to LVD mode it shall cause a reset event. In response to the transceiver mode change reset event, a SCSI target port shall create a unit attention condition for all initiators. The sense key shall be set to Unit Atten- tion, and the additional sense code set to Transceiver Mode Changed to LVD.

5.5Asynchronous condition recovery

Part of the asynchronous condition recovery stem are sets of pointers to storage areas where information is kept that, in addition to being necessary to the start of a task, allows tasks to be interrupted, restarted or repeated. The following subsections describe these pointers.

5.5.1SCSI pointers

The SCSI architecture provides for sets of pointers to be kept within each initiator task control area. These pointers are in sets of three pointers per set. The pointers in each set point to three storage area sections in the initiator. The three sections contain the following information:

a.A command from initiator to target.

b.Status (from target) associated with the command.

c.Data (to/from target) associated with the command.

Of these three-pointer sets there are two types:

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