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Commands: Log Sense (4Dh) Page 69

When a previously used cartridge is inserted, the total counts are updated to the

values contained in the Tape Log of the inserted cassette. The total counts can be

read with the LOG SENSE command.

Also, page 30 contains a set of current counts. The current usage counts are not

part of the Tape Log. They are initialized to 0 when the cartridge is inserted. While

the tape is in use, the current usage counts are incremented according to the DDS

format definitions as an event occurs. These counts cannot be changed by the

initiator.

When the cartridge is ejected or the UNLOAD command is received, the current

usage counts are saved in the previous counts. The total counts are also updated to

indicate the new totals. This updated data is written to the tape in the Tape Log

area. The Tape Log data is not cleared by any reset and cannot be changed with

the LOG SELECT command.

Note: If power is lost before the update data is written to the tape, the Tape

Log area is not updated. Also, if the cassette is write protected, the Tape

Log area is not updated when the cassette is ejected. The drive does NOT

post a Check Condition for this case.

Each page 30 count is a positive binary value. The counts do not overflow. Once a

count reaches its maximum value, that maximum value is always returned. The

counts do not roll over at the maximum value.

A single-partition tape contains one Tape Log; a dual-partition tape contains two

Tape Logs. The appropriate Tape Log is returned as determined by the previously

selected partition.

The page 30 parameter codes are listed in the following table (* indicates that the

most significant 4 bits are 0).

Name Code Length Description

Current

Groups

Written

0001 3* This count is the number of groups written to the partition since

the cartridge was inserted. Each group contains 126 KB of

data.

Current

Rewritten

Frames

0002 2 This count is the number of rewritten frames within the

partitions since the cartridge was inserted. It is incremented by

one each time a series of frames is rewritten. Frames are

rewritten following an error detected by the RAW check. If the

data written during the rewrite is also found to be bad by the

RAW check, the series of frames is rewritten again, and this

count is incremented by 1 again.

Current

Groups Read

0003 3* This count is the number of groups read from the cartridge

since it was inserted.

Current ECC

C3 Corrections

0004 2 This count is the number of times the drive used the C3 ECC

correction to recover data from the partition since the cartridge

was inserted.

Groups

Written

0005 3* This count is the number of groups written to the partition

during the last cartridge usage cycle.

Rewritten

Frames

0006 2 This count is the number of frames rewritten in the partition

during the last cartridge usage cycle. It is greater than or equal

to the last current rewritten frames count prior to the Tape Log

being updated when the cartridge is ejected.

Groups Read

0007 3* This count is the number of groups read from the partition

during the last cartridge usage cycle.

1 2 ... 76 77 78 79 80 81 82 83 84 85 86 ... 180 181

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Quantum DAT 24 Drive Guia do Utilizador Página 81

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