Exabyte EXB-8205 Instrucciones de operaciones descargar pdf (Pagina 372)

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Sample Application for Directory Support

The step-by-step description that follows explains how to create this

data structure and access the data using the READ POSITION and

LOCATE commands.

Restrictions on Similar Applications

The sample application in this appendix demonstrates only a

suggested implementation of directory support. You may choose to

implement directory support in any manner that fits your needs, with

the following restrictions:

Do not include filemarks in the master directory. The first

filemark on the tape must be the one written at the end of the pad

created after the space for the master directory.

The master directory must be 10 MBytes or less in length.

Important

When you are using 8500c format, disable data

compression by setting the DCE bit on the Data

Compression Page of the MODE SELECT command

to 0 when writing the master directory pad and the

pad following it. This ensures that the pad areas are

the correct length. After writing the pad areas, you

can set the DCE bit back to 1 to enable compression.

Note that if you are writing the pad areas in 8200c

format, the CTS will not compress the data written

before the first filemark on tape. This ensures that

these pad areas are the correct length in this data

format. Data compression will automatically resume

after the first filemark.

To ensure that no two logical blocks on a directory support tape

have the same logical block address, the number of logical blocks

(records) in the master directory must be less than the number of

logical blocks used to create the pad areas. For this reason, you

may find it helpful to write fixed-length blocks of 1 KByte (or less)

in length when you are creating the pad areas.

May 1994 EXB-8205 and EXB-8505

(Standard and XL)

B-3

Appendix B Directory Support

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