User Guide

Ampex 1308911-02 2-5
Software Overview Tape Drive Behavior
2.3 Tape Drive Behavior
When the Ampex tape drive software is installed on a UNIX platform, the host creates a
number of device special files which provide access to the tape device driver. Each device
special file defines a unique set of interface parameters that establish a particular operational
behavior for the tape drive.
For additional information on device special files, see Section 4 and Appendix B.
• Section 4 describes how the interface parameter settings affect common tape drive
operations.
• Appendix B lists the default device special file choices for each host platform,
summarizes the behavior specified by each file, provides detailed description of the
interface parameters, and cross references the interface parameters to descriptions of the
actions that they control on open, while open, or on close.
2.4 libdd2 API Overview
The libdd2 API features simple, compact, and direct functions that afford program control of
all salient tape and drive operations except for open, close, read, and write which are
accomplished using standard UNIX system calls. Detailed knowledge of the hardware and
SCSI interface are not necessary.
Table 2-2. DST/DIS Tape Device Driver Interfaces
Interface Description
COMMAND LINE INTERFACES
Ampex dd2 utilities
The dd2 utilities take full advantage of the DD-2 tape format. They are the
recommended method for controlling the tape drive from the command line.
UNIX mt utility
The mt utility provides an alternate method of controlling the tape drive from the
command line but it doesn’t take full advantage of the DD-2 tape format. Use this
utility only when necessary for compatibility with existing UNIX tape handling
programs.
UNIX data transfer
utilities
UNIX provides several utilities for reading from and writing to tape. Two of the more
common ones are dd and tar (including enhanced versions such as ftar, GNU tar, and so
forth.