Exabyte EXB-8205 Instruções de Operação descarregar pdf (Página 87)

As shown in Figure 3-1, the first partition on a dual-partition tape is

Partition 1, and the second partition is Partition 0. For a

dual-partition tape, the following areas correspond:

The physical beginning of the tape (PBOT) is equivalent to the

physical beginning of the first partition (PBOP 1).

The logical beginning of the tape (LBOT) is equivalent to the

logical beginning of the first partition (LBOP 1).

The logical end of the second partition (LEOP 0) is equivalent to

the logical end of the tape (LEOT).

The physical end of the second partition (PEOP 0) is equivalent to

the physical end of the tape (PEOT).

Because they are treated as separate entities by the EXB-8505,

partitions provide a safe, effective way to maintain a directory on a

tape. Typically, the first partition on the tape is used as the directory,

and the second partition (the remainder of the tape) is used for the

archived data. Because the partitions are independent of each other,

there is never any risk of overwriting archived data in the second

partition when you update the directory in the first partition.

How Do You Create Partitions?

To create a partitioned tape, you format the tape using the MODE

SELECT (15h) command. The MODE SELECT command lets you

specify how many partitions will be on the tape (one or two) and

what size the first partition will be (the size of the second partition is

always the remainder of the tape).

Note that a standard blank tape is considered to have one partition.

You do not need to format a blank tape if you want only one

partition. The only time you would specify one partition when you

are formatting a tape is if you want to change a dual-partition tape

back to a single-partition tape.

To create and use partitions, the EXB-8505 must be set to read and

write in 8500c format. You cannot write data in different formats in

two separate partitions.

A summary of the steps you take to create a dual-partition tape from

an unformatted (or single-partition) tape follows. (Refer to Chapter

10 for specific details about using the MODE SELECT command.)

May 1994 EXB-8205 and EXB-8505

(Standard and XL)

3-25

3 Implementing CTS Operations

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