User manual QUANTUM DLT4000

[. . . ] DLTTM4000 Tape Drive Product Manual November 10, 2003 81-60043-04 Quantum reserves the right to make changes and improvements to its products, without incurring any obligation to incorporate such changes or improvements in units previously sold or shipped. Quantum reserves the right to make changes to this product manual without incurring any obligation to notify recipients of earlier versions of the product manual. You can request Quantum publications from your Quantum Sales Representative or order them directly from Quantum. Publication Number: 81-60043-04, November 10, 2003 SERVICE CENTERS Quantum Service Center 715 Sycamore Avenue Milpitas, California 95035 Phone (888) 827-3378 FAX: (800) 4DISKFAX BBS: (800) 472-9799 Quantum Asia-Pacific Pte. 50 Tagore Lane #b1-04 Singapore, 2678 Phone: (65) 450-9333 FAX: (65) 452-2544 Quantum Customer Service Quantum Ireland, Ltd. Finnabair Industrial Park Dundalk County Louth, Ireland Phone: (353) 42-55350 Fax: (353) 45-55355 Copyright © 1995-2001 by Quantum Corporation. [. . . ] When an I/O process becomes active, the three saved pointers are copied to the initiator as current pointers. There is only one set of current pointers in the initiator at one time. The current pointers point to the next command, data, or status byte to be transferred between the initiator's memory and the drive. The saved command pointer always points to the start of the Command Descriptor Block for the I/O process. The saved status pointer always points to the start of the status area of the I/O process. The saved data pointer always points to the start of the data area until the drive sends a SAVE DATA POINTER message for the I/O process back to the initiator. Quantum DLT 4000 Tape Drive 5-3 SCSI Commands In response to the SAVE DATA POINTER message, the initiator stores the value of the current data pointer into the saved data pointer for that I/O process. The drive can restore the current pointer from the saved pointer value for the active I/O process by sending a RESTORE POINTERS message to the initiator. The initiator then copies the set of saved pointers into the set of current pointers. Whenever a drive disconnects from the SCSI Bus, only the set of saved pointers is retained in the initiator. The set of current pointers is restored from the set of saved pointers when the I/O process is reconnected. 5. 1. 2 Command Descriptor Block An initiator communicates with the drive by sending a 6- or 10-byte Command Descriptor Block that contains the parameters for the specific command. The SCSI command's operation code is always the first byte in the Command Descriptor Block and a control field is the last byte. For some commands, the Command Descriptor Block is accompanied by a list of parameters sent during the DATA OUT phase. Figure 5­1 shows the format of a typical 6-byte Command Descriptor Block. Table 5-2 contains a description of the Command Descriptor Block fields. Bit Byte 0 7 6 5 4 3 2 1 0 Operation Code (MSB) 1 Logical Unit Number (LUN) Logical Block Address (LBA) Logical Block Address (LBA) 2-3 (LSB) 4 Transfer Length, Parameter List Length, or Allocation Length 5 Control NOTE: Unless otherwise specified, all reserved bits indicated in the commands are 0. Figure 5­1 Typical Command Descriptor Block - Data Format 5-4 Quantum DLT 4000 Tape Drive SCSI Commands Table 5­2 Command Descriptor Block - Field Descriptions Field Operation Code Description The operation code specifies the command being requested. The list of supported SCSI commands and their operation codes are contained in Table 5-1. The Logical Unit Number contains the number of the device being addressed. The Logical Unit Number is ignored if the Command Descriptor Block is preceded by an IDENTIFY Message. The 6-byte READ, SEEK, and WRITE Command Descriptor Blocks contain a 21-bit Logical Block Address. The 10-byte READ, SEEK, and WRITE Command Descriptor Blocks contain a 32-bit Logical Block Address. Commands that require additional parameter data specify the length of the Logical Block Address that is needed. Relative Addressing indicates a technique used to determine the next Logical Block Address to be operated on. It defaults to a value of 0, which specifies that the Logical Block Address specifies the first logical block of a range of logical blocks to be operated on by the command. [. . . ] Only when the green Operate Handle LED is steadily lit and when the audible beep sounds, lift the tape drive's cartridge Insert/Release handle. If the green Operate Handle LED is blinking, close the handle and wait for the LED to light steadily, then lift the handle and insert the cartridge. Push the cartridge fully into the tape drive. CAUTION To prevent failures and/or damage to the handle, assist the handle to its closed position. The green Operate Handle LED extinguishes and the amber Tape in Use LED blinks to show that the tape is loading. [. . . ]