User Guide

5-18 Ampex 1308911-02

Model No.

Running Head

dst_format libdd2 API Functions

asize The size, in physical blocks, of the Group A partitions on the tape.

Minimum partition size is 235 physical blocks. However, you can use

zero to indicate that the partition takes up the remainder of the tape.

Values in the range 1-234 are not allowed. Of the speciﬁed size, 35

physical blocks are reserved for system information and therefore not

available for user data, leaving a usable minimum size of 200 physical

blocks (roughly 240 million bytes).

The

asize parameter is ignored when the format type is

DstFmtInit.

acount The number of Group A partitions per partition pattern. This value must

be in the range 1-255.

The

acount parameter is ignored if the format type is DstFmtInit.

bsize The size, in physical blocks, of the Group B partitions on the tape.

Minimum partition size is 235 physical blocks. However, you can use a

zero value here to indicate that the partition takes up the remainder of

the tape. Values in the range 1-234 are not allowed. Of the speciﬁed size,

35 physical blocks are reserved for system information and therefore

not available for user data, leaving a usable minimum size of 200

physical blocks (roughly 240 million bytes).

If the format type is

DstFmtInit or DstFmtPart, zero is the only

valid value.

bcount The number of Group B partitions per partition pattern, in the range 0-

255. A zero indicates that there is only one type of partition on the tape

(the Group A partition).

If the format type is

DstFmtInit, zero is the only valid value.

If the format type i

s DstFmtPart, one is the only valid value.

layout Tape layout, indicating how to handle allocation of partitions across

system zones. The following deﬁnitions apply:

DstPack - Packs as many partitions as possible onto the tape, allowing

any given partition to span a system zone if necessary. If there is not

enough space for a full partition between the last system zone and EOT,

the remaining space is not used.

DstStretch - Any given partition is stretched to the next system zone

if there is not room for another partition before the system zone. This

can mean that some partitions are larger than the speciﬁed size. If there

is not enough space for a full partition between the last system zone and

EOT, the last partition is extended to EOT.