Specifications

ATAPI For Streaming Tape QIC-157 Rev B

Implementation of QFA allows the Host to partition a tape into two partitions. Note that the default

configuration for a tape is a single partition. Devices supporting QFA shall allocate the two partitions as

follows:

Partition Use

0 Data

1 Directory

The partitions are created when the Host issues a Mode Select command using the Medium Partition

Page. If the fixed data partitions bit (FDP) is set to one, partition 1 (the directory track) shall be

allocated according to a format-specific allocation..

For defining a partition, the FDP bit in the Medium Partition Page is the only field that is to be used by

this specification. The remaining fields apply to additional partitions that are not defined by this

specification. QIC QFA Devices do not permit the definition of additional partitions.

5.2.1. Changing Partitions

The Host has one method available for changing partitions.

1. The Host can issue a Locate command with the change partition bit (CP) set to one. The partition

byte in the Locate command indicates which partition is to become the active partition.

5.2.2. Automatic Format Detection

As most Streaming Tape Devices are capable of reading and writing many different formats, some

formats now include MODE SENSE data within the tape header to identify the different format

options. Normally, a MODE SELECT issued prior to a read or write operation would explicitly

define the format options. If a MODE SELECT command had not been made since the mounting of

the volume or with no volume mounted, the Device shall follow these set rules to select the density

and block size that will be used implicitly:

1. If no volume is mounted and a MODE SENSE command is issued, the Device shall report its

default block size and its native format in the density code field.

2. If a blank or erased tape cartridge is inserted, and a MODE SENSE command is issued after the

load process is complete, the Device shall report the default block size and the highest density

supported for the cartridge.

If no MODE SELECT command has been made since the mounting of the volume with recorded

data, the Device shall follow these set rules to select the density and block size that will be used

implicitly:

1. MODE SENSE command is issued after the load process is complete will reflect MODE data

written in the tape header if present.

2. If MODE data is not present, the Device will detect the density from the reference burst and use

the first data block found on the tape to determine block length.

3. A MODE SENSE, SPACE to EOD, or READ command issued after the load process is

complete implicitly set the density and block size.

4. If no MODE SELECT, MODE SENSE, SPACE to EOD, or READ command is issued prior to

a WRITE command, the Device shall write at the settings for a blank tape. The Device will have