HP Surestore 28/48-Slot with DLT4000 Digital Linear Tape SCSI-2 Drive and SCSI - Page 288
Communication Methods, Host to Library Communication, Library to Host Communication
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Programmer's Tips Overview of the Online Drive Repair Communication Methods Host to Library Communication The host will communicate to the library via the SCSI "Write Buffer" command. Whenever the host wants to change the state of the drive(s), it will simply issue the appropriate "Write Buffer" command (see Chapter 3 for the information about the "Write Buffer" command). Library to Host Communication The library will communicate to the host via the SCSI "Read Buffer" command and the SCSI "Unit Attention" condition. When the library wants to inform the host of a change in the state of the drive(s), it will issue a "Unit Attention" condition (ASC=0x2A, ASCQ=0x80). This condition informs the host that it must send a "Read Buffer" command to determine the state change of the drives (see Chapter 2 for information about the "Read Buffer" command). B- 18 Appendix B
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