![background image](http://html1.mh-extra.com/html/quantum/dlttape-dlt-4000/dlttape-dlt-4000_product-manual_3688580253.webp)
SCSI Commands
Quantum DLT 4000 Tape Drive
5-153
SPACE Command (11h) (continued)
Table 5–76 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
Lowest
Blocks
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 or 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.
NOTE
Note that when spacing by sequential filemarks, the DLT 4000 tape
drive handles up to 14 sequential filemarks and still reports back a
CHECK CONDITION. After the fourteenth sequential filemark (not
reached under normal operating conditions), if EOD is encountered,
the drive sends back a status good message. Status is only reported
properly on the DLT 4000 tape drive if the number of sequential
filemarks is less than or equal to 14.
Summary of Contents for DLTtape DLT 4000
Page 1: ...DLT 4000 Tape Drive Product Manual November 10 2003 81 60043 04 ...
Page 5: ...USER MANUAL STATEMENTS FOR CLASS B EQUIPMENT continued ...
Page 6: ......
Page 24: ...About This Manual Quantum DLT 4000 Tape Drive xxiv ...
Page 62: ...Hardware Implementation 2 28 Quantum DLT 4000 Tape Drive ...
Page 100: ...Messages 4 12 Quantum DLT 4000 Tape Drive ...
Page 264: ...SCSI Commands 5 164 Quantum DLT 4000 Tape Drive ...
Page 274: ...Appendix B EEPROM Resident Bugcheck and Event Logs B 6 Quantum DLT 4000 Tape System ...
Page 280: ...Appendix C Updating the Firmware C 6 Quantum DLT 4000 Tape Drive ...
Page 298: ...Index Index 6 Quantum DLT4000 Tape Drive ...
Page 299: ......