Command Processing
The IDD executes the REQUEST SENSE command normally and sends the sense data which indicate the UNIT ATTENTION condition and are being held to the INIT. At this time, the UNIT ATTENTION condition for that INIT is cleared.
1.5.3UNIT ATTENTION condition multiple hold
If any UNIT ATTENTION condition is generated and a new UNIT ATTENTION condition is generated for a different reason before the INIT for which the first UNIT ATTENTION condition was held clears it, those UNIT ATTENTION conditions are held together, and the IDD reports these multiple UNIT ATTENTION conditions in sequence. For example, a “Mode parameters changed,” “Spindle Synchronized” or “Spindle not Synchronized” or other UNIT ATTENTION condition may be reported after the “Power on, RESET or TARGET RESET occurred” UNIT ATTENTION condition is reported.
1.6Sense Data Hold State
1.6.1Sense data hold condition
The IDD generates sense data if any of the following conditions occurs and enters the sense data hold state until the conditions for cancellation, described in Section 1.6.2, are established. The sense data which are generated, are held for each individual INIT that issued the applicable command. The sense data hold state is also maintained individually for each INIT which is their object.
1)If the IDD reports a CHECK CONDITION status, sense data is generated for the command that was terminated by the CHECK CONDITION status.
2)If a fatal error occurs on the SCSI bus and the IDD forcibly enters the BUS FREE phase, sense data is generated for the command that was being executed on the SCSI bus. However, if the LUN cannot be identified by the point when the error occurs, the IDD does not generate sense data.
3)Since it is impossible for reconnection processing to be executed without a response from the INIT in the RESELECTION phase, if the IDD clears the command that is necessary for reconnection processing, sense data is generated for that command.
Notes:
1.In the case of 3) above, the IDD does not clearly inform the INIT of the occurrence of an error, but terminates the command abnormally and enters the sense data hold state. If a long period of time passes with no response from the IDD, the INIT that issued the command should issue a REQUEST SENSE command and confirm the content of the error.
2.If the INIT which is the object of holding of sense data cannot be identified because the INIT’s SCSI ID was not notified in the SELECTION phase, the INIT enters an unspecified special sense data hold state. In this case, the IDD regards this as the INIT that is the object of holding of the sense data starting a new SELECTION phase in which the INIT’s SCSI ID is not notified.
1.6.2Response and release conditions at sense data hold state
The response of the IDD when it receives a new command while it is in the sense data hold state, and conditions for releasing the sense data hold state are shown below.
1 - 22 |
