Among common storage media, which one is inherently sequential-access only (i.e., cannot provide true random access to arbitrary records)?
-
AFloppy disk
-
BHard disk
-
CMagnetic tape
-
DROM
-
EFlash drive
Answer
Correct Answer: Magnetic tape
Explanation
Introduction / Context:Data access patterns vary across storage media. Understanding whether a medium supports random access or only sequential access is crucial for system performance planning and archival design.
Given Data / Assumptions:
- 'Sequential access' means data must be read in order until the desired location is reached.
- 'Random access' means the device can reposition quickly to access any block directly.
- Typical devices: floppy disk, hard disk, ROM, and magnetic tape.
Concept / Approach:
Magnetic tape stores data linearly along a long strip. To reach a given record, the tape must be wound forward or backward to that location—this is sequential by nature. Disks (floppy/hard) use addressable tracks and sectors, enabling near-random access. ROM is also random access by address lines.
Step-by-Step Solution:
Identify media with mechanical linear scanning → magnetic tape.Disks/ROM provide addressable blocks → random access.Therefore, magnetic tape is sequential-only.Verification / Alternative check:
Backup/archival systems based on LTO tape require tape positioning and are optimized for streaming throughput rather than random I/O, confirming sequential semantics.
Why Other Options Are Wrong:
- Floppy/Hard disks: random access via seek and rotational latency.
- ROM: direct addressing supports random fetches.
- Flash drive: solid-state storage with random access.
Common Pitfalls:
Confusing file system behavior over a medium with the medium's physical access method; even if a file is fragmented, disks remain random-access media.
Final Answer:
Magnetic tape