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SCSI Commands

Quantum DLT 8000 Tape System 5-217

SPACE Command (11h) (continued)

Table 5–99 SPACE Command Data — Field Descriptions (continued)

Field Name Description

Count When spacing over blocks or marks, the Count field is interpreted as

follows:

A positive value N causes forward motion over N blocks or marks. The

tape is logically positioned after the Nth block or mark on the EOM or

EOP side.

A value of 0 causes no change in logical position.

A negative value -N (two’s complement notation) causes reverse

movement over N blocks or marks. The tape is logically positioned on

the BOM or BOP side of the Nth block or mark.

When spacing to EOD, the Count field is ignored. Forward movement

occurs until the drive encounters EOD. The position is such that a

subsequent WRITE command would append data after the last object

that has been written to tape before EOD.

When executing SPACE, the tape drive implements the following hierarchy:

HIGHEST BOM/P or EOM/P*

EOD**

Filemarks / Sequential Filemarks

LOWEST Blocks

* Beginning of Media/Partition or End of Media/Partition

**End of Data

The tape drive supports only one partition.

Note that a “SPACE Sequential Filemarks” is a SPACE to the first occurrence of n

filemarks written sequentially.

A SPACE command in the form “SPACE N blocks” will halt with GOOD status after

the Nth block, or with CHECK CONDITION status on any occurrence of Filemark,

EOD, BOM/P, or EOM/P. A command “SPACE N Filemarks” will halt on the Nth

Filemark with GOOD status on any occurrence of EOD, BOM/P, or EOM/P.

Depending on the size of blocks, read ahead data in the buffer allows some spacing

requests to be satisfied without actual tape movement.

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Quantum DLT 8000 Manual Página 361