Header fields
Mode Data Length MODE SELECT: Mode Data Length field must be zero.
MODE SENSE: Mode Data Length field is set to the number of bytes of data available to
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| return excluding itself (in other words, the number of actual bytes available is |
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| mode data length + 1 for |
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| SENSE). |
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| NOTE: The actual amount returned may be truncated to the allocation length |
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| for the command. |
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Medium Type | 00h | The usual medium type when the drive is in normal tape drive mode. |
| 01h | WORM media is loaded |
| 80h | The tape drive is in |
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WP | Write Protect. Ignored for MODE SELECT. | |
| 0 | MODE SENSE: The tape is |
| 1 | MODE SENSE: The tape is |
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Buffered Mode | 0 | The drive will not report GOOD status on Write and Write Filemarks commands until all |
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| data (blocks and filemarks) has been successfully written to tape. |
1The drive will report GOOD status for Write and Write Filemarks commands as soon as all the data or marks specified in the command have been transferred to the data buffer. Data for multiple commands from different initiators may be buffered. This is the default value.
NOTE: It is strongly recommended that this field is set to 1, otherwise there will be significant performance penalties. A method of flushing the buffer to tape without changing logical position is available with the Write Filemarks command.
2The drive will report GOOD status for Write and Write Filemarks commands as soon as all the data or marks specified in the command have been transferred to the data buffer and all buffered data from different initiators has been successfully written to the tape.
Speed | 0 | The Speed field is not used and should be zero. |
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Block Descriptor | Only the values 0 and 8 are valid. Any value other than 0 or 8, CHECK CONDITION status is | |
Length | reported. See the Parameter List check for details of the sense data generated. | |
| 0 | No block descriptor is being transferred. |
| 8 | The Mode Parameter header must be followed by the |
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| described in the next section. |
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Commands
MODE SELECT 15h/55h 75