Seagate Technology 10002475-003, Product Description Manual

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Chapter 6 Tape Format
Page 58 STT8000 ATAPI Minicartridge Drive
Blocks
Information in the Block Control byte determines the type of block being
recorded except for ECC blocks which are recognized by their block numbers.
Also, information about the number of user data bytes available in each data
block is recorded in the Block Control byte of the block.
The Data Field of the blocks always contain 512 bytes. However, the number of
valid data bytes in the block may be less than 512.
The seven different types of blocks are as follows:
z Data blocks contain user data. A full Data block contains 512 bytes;
however, data block can contain from 1 through 511 valid data bytes
depending on the selected logical block size of the host.
z Media Header blocks contain specific host., drive, and vendor
information as well as the Volume Directory. The first frame on the
Directory Track is teh Media Header Frame. This frame contains 52 Media
Header blocks (plus the normal 12 ECC blocks).
z Information blocks—Filemark blocks, Setmark blocks, and Cancelmark
blocks—contain specific types of information. Filemark blocks are physical
blocks written to tape in response to a host WRITE FILEMARKS command.
Setmark blocks are physical blocks written to tape in response to a host
WRITE SETMARKS command. Cancelmark blocks are physical blocks
written to tape under firmware control.
z Filler blocks contain no valid information in the data area. These blocks
are used to fill incomplete frames.
z EOD blocks are absolute indicators of the end of recorded data.
z ECC blocks contain error correction parity bytes that are used to
ensuredata integrity during read operations.
z Track ID blocks are recorded as part of the preformatting process of the
cartridge.
Tape Reference Servo Pattern
To increase track density, a track servo reference pattern is prerecorded on the
tape at the factory. The pattern is recorded referenced to servo patterns in the
region between the beginning-of-tape (BOT) hole and the load point market
(LP) hole. The same pattern is recorded between the end-of-tape (EOT) hole and
the early warning (EW) hole. The servo pattern is written across the entire
width of the tape.