Quantum DAT 24 Drive Betriebsanweisung PDF herunterladen (Seite 168)

Page 156 DDS-4 SCSI Interface Manual, Rev. B

• If an unrecoverable data error is encountered, Check Condition is returned,

Extended Sense Key is set to Medium Error, and Extended Sense Valid bit is

set, indicating Residual Length is nonzero.

Space by Position Functions

The Count field is not applicable in space-to-EOD functions.

In the space-to-EOD function, the tape is positioned such that a subsequent WRITE

command appends data to the last recorded information on the tape. This

positioning is done at high search speed.

The space-to-EOD function is useful in support of user-defined directories located at

the end of recorded data.

• If physical EOT is encountered while spacing to end of data, Check Condition

Status is returned and Extended Sense is set to Medium Error.

• If unrecoverable data error is encountered, Check Condition Status is returned,

Extended Sense Key is set to Medium Error, and Extended Sense Valid bit is

set, indicating Residual Length is non-zero.

Space and the RSMK Bit

A Report Setmark (RSMK) bit determines whether or not the drive recognizes

setmarks during a SPACE operation. If the value of the RSMK bit is 1, the drive

recognizes and reports setmarks when searching for the target. If the value of the bit

is 0, the drive ignores setmarks during execution of the SPACE command.

Assume that the data was written on the tape as shown in the following table.

Block 1 2 3 4 5 6 7 8 9 10 11 12 13 14

BOT D S S S S S D D D D D D D cod

Position A B C D E F

Similar with the LOCATE command, if the RSMK bit is 0 when the SPACE

command is issued, all the setmarks are logically grouped with its nearest Data

Block on its BOT side to form a single logical block. The following table shows the

logical blocks when the RSMK bit is set to 0. In the table, the data block in block

number 1 together with five setmarks in blocks number 12-6 are considered as one

logical block.

Block 1 1 1 1 1 1 2 3 4 5 6 7 8 9

BOT D S S S S S D D D D D D D cod

If the RSMK bit is 1 in the CDB when the SPACE command is issued, then the

setmark is recognized and reported during execution of the SPACE operation. The

following table shows the logical blocks.

Block 1 2 3 4 5 6 7 8 9 10 11 12 13 14

BOT D S S S S S D D D D D D D cod

1 2 ... 163 164 165 166 167 168 169 170 171 172 173 ... 180 181

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Quantum DAT 24 Drive Betriebsanweisung Seite 168