The directory /srv/data already holds 40 GB of files on the root filesystem. You add a new disk and mount it on /srv/data. What happens to the 40 GB that were there before?
LPIC-1 Exam 101-500, objective 102. Linux installation and package management hard
Machine-checked — no person has signed for it. This question was read against the source cited below by an automated pass, which found no contradiction. That is a weaker claim than it sounds: the same kind of process wrote the question, so it can confirm its own mistake.
Treat it as a good draft rather than as settled fact, and read the source below before you rely on it. It is not used in mock exams here — only questions a person has signed for are.
How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.
The options
Correct They are hidden while the new filesystem is mounted, but still occupy space on the root filesystem.
Correct. Mounting shadows the directory's previous contents; they reappear, still consuming the same blocks, once the new filesystem is unmounted.
Not correct They are copied onto the new filesystem automatically as part of the mount.
Wrong. mount only attaches a filesystem at a point in the tree; it never moves or copies data. Migrating the files is a separate, manual step.
Not correct They are deleted, because mounting over a non-empty directory truncates it.
Wrong. Nothing is written to the underlying filesystem, so no data is destroyed; this is a common but unfounded fear.
Not correct The mount fails, because a mount point must be an empty directory.
Wrong. An empty mount point is a convention, not a rule; mount will happily attach a filesystem over a populated directory.
Why
A mount point is only a name in the namespace, and mounting rebinds that name to the root of the new filesystem. The old inodes remain allocated on the underlying filesystem and are reachable again after umount, or through a second mount of the parent filesystem elsewhere. This is why disk usage reported by du on the mounted tree can disagree with the free space df reports for the filesystem underneath.
Where this comes from
- Cited
- manual page mount(8)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 102 and space the ones you get wrong.
More questions on this objective
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