Exabyte EXB-8205 Instruções de Operação descarregar pdf (Página 91)

Writing Data in Partitions

To write data, use the WRITE (0Ah) command as you would with a

standard tape. However, remember that if you want to write data in

the partition the tape is not currently in, you must first use the MODE

SELECT command to indicate that you want to change partitions.

The EXB-8505 repositions the tape to the new partition after it receives

a tape motion command such as SPACE (11h).

Writing to PEOP When you are writing data to the first partition,

you can never overwrite the end of the partition. If the EXB-8505

encounters the logical end of the partition (LEOP), it returns

Check Condition status as if it had encountered the logical end of

the tape (LEOT). You can choose to write to the physical end of

the partition (PEOP), but you cannot overwrite PEOP (refer to

Appendix C for the amount of data space available between LEOP

and PEOP). If you encounter PEOP in the first partition while

writing data, the EXB-8505 reacts as if it encountered the physical

end of the tape (PEOT). The write operation stops and any

buffered data is not written to tape.

Data Format Restriction Although partitions are treated as

separate entities by the EXB-8505, you cannot use different data

formats in the two partitions. If you attempt to change data

formats between partitions, you will destroy the partition

information. You must create the partitions in 8500c format, and

you cannot use the Density Code field in the MODE SELECT

command to change formats anywhere on the tape. However,

you can turn compression on and off in either partition.

Locating Data Blocks in Partitions

Use the READ POSITION (34h) command to identify the position of a

specific data block on a dual-partition tape as you would on a

standard tape. The READ POSITION data returned by the EXB-8505

indicates the block address at the current location. It also indicates

the number of the partition the tape is located in.

When you use the LOCATE (2Bh) command on a dual-partition tape,

first specify which partition the EXB-8505 should search for the

requested block. If you need to change partitions, set the CP (Change

Partition) bit to 1. Then, specify the number of the partition you want

the tape moved to in the Partition field. The EXB-8505 moves the

tape to the requested partition, then searches for the requested block.

May 1994 EXB-8205 and EXB-8505

(Standard and XL)

3-29

3 Implementing CTS Operations

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Exabyte EXB-8205 Instruções de Operação Página 91