Quantum 1200 Series DAT Autochanger Guide de l'utilisateur télécharger pdf (Page 49)

SDLT 600 SCSI Interface Guide Chapter 4: SCSI Commands

81-81200-02 REV A01 January 2005 4-7

4.1.3 Unit Attention Condition

Queued Unit Attentions are implemented on the SDLT tape drive and are maintained separately for

each valid LUN for each initiator. Unit Attentions are created in each of the following circumstances:

• At power-on.

• At Bus Reset

• On a BUS DEVICE RESET message

• When the medium may have changed asynchronously.

• When another initiator changes the Mode parameters.

• When a firmware (microcode) update has completed.

• Change of SCSI bus transceivers (SE or LVD).

Up to three Unit Attentions may be queued for each initiator. If an initiator does not clear its queued

Unit Attentions, any additional Unit Attention conditions are not reported.

4.1.4 Behavior at Power-On

The SDLT tape drive’s behavior at power-on consists of the following:

• The drive’s SCSI lines are set to high impedance.

• The design of the drive prevents it from generating any spurious signals on the SCSI bus during

power-on.

• Within five seconds of power-on, the tape drive responds to SCSI bus selections and returns

appropriate, normal responses. The drive returns tape motion commands with CHECK

CONDITION status, Sense Key set to NOT READY, until the tape medium is ready.

• The drive rewinds the tape to Beginning of Tape (BOT).

• The drive goes through a calibration process at power-on and loading of media.

• The drive recognizes multiple, successive SCSI bus resets and SCSI bus resets of arbitrarily long

duration. The drive recovers within the time limits specified above following the last SCSI bus

reset.

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Quantum 1200 Series DAT Autochanger Guide de l'utilisateur Page 49