EX200 Configure local storage Practice Question
A system administrator tries to mount a filesystem but receives the error: 'mount: /dev/sdb1 is already mounted or /data busy'. The filesystem is not listed in the mount output. What is the most likely cause?
⚠ Common exam trap
Red Hat often tests the distinction between 'device busy' (device already mounted elsewhere) and 'mount point busy' (directory in use), leading candidates to incorrectly assume the device is already mounted when the error actually points to the mount point being active.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The mount point /data is in use by a process
The error message 'mount: /dev/sdb1 is already mounted or /data busy' indicates that the mount point /data is currently in use by a process, preventing the mount operation. Even though the filesystem is not listed in the mount output, a process may have an open file descriptor or be using /data as its current working directory, which keeps the directory busy. The 'lsof' or 'fuser' commands can be used to identify the offending process.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The kernel does not have the filesystem driver loaded
Why it's wrong here
If the required filesystem driver were absent, the kernel's VFS layer would fail with an 'unknown filesystem type' error when parsing the source device. This error specifically names the unsupported filesystem format, not the target mount point. Since the administrator sees a busy error instead, a missing driver cannot be the cause.
- ✓
The mount point /data is in use by a process
Why this is correct
The kernel refuses to mount over a directory that is currently being used as a process's current working directory or that has open file descriptors referencing it. Mounting would hide the existing directory contents, creating a security and consistency risk, so the kernel returns a 'mount point is busy' (EBUSY) error. This matches the administrator's symptom, making it the correct explanation.
- ✗
The device is already mounted on another mount point
Why it's wrong here
If the device were already mounted elsewhere, the kernel's mount table would show a duplicate source. Mounting the same device again typically yields an error like 'device is busy' or 'already mounted' that points to the source device, not the target directory. Here the reported busy condition is about the mount point /data, so this option is irrelevant.
- ✗
The filesystem is corrupted
Why it's wrong here
Filesystem corruption usually prevents the kernel from reading the superblock or metadata, producing errors such as 'wrong fs type, bad option, bad superblock' or an I/O error. Those failures occur before the kernel checks whether the target directory is in use. Since the observed error is a busy condition on the mount point, corruption is an unlikely and unrelated cause.
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