Quantum SDLC 2.7, Справочное руководство

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292 SCSI Guide
SCSI Operations
The following detail Scalar 1000 and Scalar 10K SCSI communication behavior.
Parity Checking
To enable parity checking on information received by the library, set the parity bit on the Parity Page of the
MODE SELECT command.
Disconnection
The library disconnects from the SCSI bus whenever a command requires a lengthy time to complete. The
library receives permission to disconnect from the initiator. The initiator grants permission by:
• Selecting the library with the Attention signal.
• Sending an Identify message with the DiscPriv bit set to 1.
Once the command processing completes, the library reselects the initiator and sends the Identify message.
Resetting the Library
The library is reset by a Power-On Reset (POR) or a SCSI Device Reset.
Power-On Behavior
• The library goes to the Bus Free phase.
• The checksum of the flash EEPROM is validated.
• All library parameters are loaded with either saved or default values.
• A Power On SelfTest is performed.
• The library responds to the SCSI bus within 10 seconds of power on.
SCSI Device Reset Behavior
• The library goes to the Bus Free phase.
• All library parameters are returned to their saved or default values.
• A Self Test is performed.
• The library responds to the SCSI bus within 250 milliseconds.
Status Value Description
Good 00h The library successfully completed the command.
Check
Condition 02h An error condition occurred during command processing. The
REQUEST SENSE command responds with detailed error information.
Busy 08h The target is busy. This status is returned when the device is unable to
accept a command from an otherwise acceptable initiator. The initiator
should reissue the command at a later time.
Reservation
Conflict 18h This status is returned by the library when a SCSI initiator attempts to
access the library after it is reserved by another initiator with a
RESERVE command.