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2 Recording Format
Gap Bytes
A gap byte is a byte containing undefined data that the tape drive uses to fill empty space in a physical block. The tape drive may automatically write gap bytes in the following cases:
At the end of a write operation.
Before writing a filemark.
Before writing a setmark
When it is physically impossible to start the next logical block in the physical block because less than three bytes are available. (This is because the
Figure 2-10 shows how gap bytes can be used to fill empty space at the end of a physical block. Gap bytes cannot be accessed by any SCSI command.
Header, 2 logical blocks, header, 2 logical blocks, and 2 gap bytes
256 bytes
256 bytes
256 bytes
250 bytes
2 gap bytes |
Figure 2-10 Gap bytes (one physical block)
May 1994 | ||
| (Standard and XL) |
|