ITPEC FE Morning October 2021 Question 18
Topic: Software
There exist methods to obtain backup files for the purpose of recovering files and managing generations. Which of the following is an appropriate description for those methods or procedures?
Explanation
Differential copies changes since the last full backup; incremental copies changes since the last backup of any kind — the two methods differ only in their reference point.
- •Differential: each run copies everything changed since the last full backup, so each set grows until the next full backup. A restore needs the full backup plus the latest differential.
- •Incremental: each run copies only what changed since the previous backup, whatever its type, so sets stay small. A restore needs the full backup plus every incremental after it, in order.
Answer (a)
Why not others:
- •(b) — reversed: incremental restores are the slower ones, because the latest versions are spread across the full backup and the whole chain of incrementals; a differential restore needs only two sets
- •(c) — multiplexed backup means writing several backup streams interleaved onto one device at the same time to keep it busy; it is not a mix of backup types
- •(d) — reversed: a differential copies more files each time (everything since the full backup), so it is the slower one to take
Key rule: Incremental is fast to back up and slow to restore; differential is slower to back up and fast to restore.
Software · AI-written, may contain errors
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