In data storage technologies, especially when using magnetic tape media, how can the records in a file or on tape be accessed, and what limitations does this impose compared with disk-based random access?

Introduction / Context:
Understanding storage access methods is fundamental in computer organization and database management. Magnetic tape is a classic example of a sequential storage medium, while modern disks and SSDs support true random access. This question probes whether you know how records are accessed on tape and the implications for performance and processing logic.

Given Data / Assumptions:

• The medium referenced is magnetic tape, which physically stores data in linear tracks.
• We are comparing access patterns (sequential versus random).
• General file transfer and organization practices are possible if the medium allows reading.

Concept / Approach:

Tape devices are sequential: to reach record N, the drive must pass through the preceding N−1 records. This contrasts with disk-based random access, where a block can be fetched directly by its address. Sequential access affects batch processing, recovery, and sort/merge operations but does not prevent copying or reorganizing data onto other media.

Step-by-Step Solution:

Verification / Alternative check:

Operating system tape utilities (e.g., backup/restore) move the tape head sequentially; random seeks are emulated by fast forward/rewind, not true block-level access.

Why Other Options Are Wrong:

“Are meant for backup” is common but not required; tapes can store any data.

“Have to be arranged in a key sequence” is not mandatory; sequence helps, but the medium does not impose key ordering.

“Cannot be transferred to a disk file” is false; copying is routine.

“None” is incorrect because sequential-only access is the defining trait.

Common Pitfalls:

Confusing practical usage (backups) with inherent capability. The core distinction is access method, not purpose.

Final Answer:

can only be accessed serially