Exabyte EXB-8505 8mm - Manual (Page 54)

Short Filemarks
In 8500, 8500c, and 8200c formats, a short filemark consists of a single,
1-KByte physical block. This block contains information identifying
the filemark’s number and location on the tape.
In 8200 format, a short filemark consists of 21 tracks of information.
Setmarks (EXB-8505 and EXB-8505XL only)
When the EXB-8505 or EXB-8505XL is writing in 8500c format, you
can issue a WRITE FILEMARKS (10h) command to write one or more
setmarks to tape. Setmarks provide an additional way to indicate data
boundaries on the tape; in a sense, they can be thought of as
“hierarchically superior” filemarks.
Each setmark is 48 KBytes long and consists of the following:
Two gap tracks at the beginning
Two tracks of setmark physical blocks
Two gap tracks at the end
You can issue a SPACE (11h) command to space to setmarks;
however, you can also use a MODE SELECT (15h) command to
suppress setmark detection during read, verify, space block, and
space filemark operations.
End of Data (EOD)
When writing tapes in 8500, 8500c, or 8200c format, the tape drive
writes an end-of-data (EOD) mark after the last data written to tape.
In 8500 and 8500c formats, the EOD mark consists of one or more gap
tracks, erase gaps, and 600 tracks of end-of-data blocks. In 8200c
format, the EOD mark consists of 249 erase gap tracks and 600 tracks
of end-of-data blocks.
These tracks are used when the initiator issues a SPACE (11h)
command to locate the last data written to tape. The tape drive
overwrites the EOD mark when it writes additional data to tape.
In 8200 format, there is no EOD mark, but you can space to the end of
data.
2-18 EXB-8205 and EXB-8505 510504
(Standard and XL)
2 Recording Format