EX200 Configure local storage Practice Question
Exhibit
# cat /etc/fstab # # /etc/fstab # Created by anaconda on Mon Jul 19 10:15:30 2021 # # Accessible filesystems, by reference, are maintained under '/dev/disk/' # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info # UUID=12345678-1234-1234-1234-123456789abc / xfs defaults 0 0 UUID=abcdef12-3456-7890-abcd-ef1234567890 /boot ext4 defaults 1 2 UUID=deadbeef-cafe-babe-1234-567890abcdef swap swap defaults 0 0 /dev/vdb1 /mnt/data ext4 defaults 0 0 # blkid /dev/vdb1 /dev/vdb1: UUID="a1b2c3d4-e5f6-7890-abcd-ef1234567890" TYPE="ext4" # mount -a mount: /mnt/data: can't find /dev/vdb1 in /etc/fstab.
Refer to the exhibit. An administrator attempts to mount all filesystems using 'mount -a' and receives an error. What is the most likely cause?
⚠ Common exam trap
Red Hat RHCSA often tests the distinction between errors caused by a missing device node versus a missing mount point or filesystem corruption, and candidates mistakenly assume the error is due to a missing mount point or a corrupted filesystem without reading the exact error message.
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 entry for /dev/vdb1 in /etc/fstab uses a device name that does not exist.
The error occurs because the entry in /etc/fstab for /dev/vdb1 references a device name that does not exist on the system. When 'mount -a' is executed, it reads /etc/fstab and attempts to mount each filesystem; if the device node is missing (e.g., due to a typo, incorrect kernel name, or the device not being attached), the mount fails with an error like 'mount: special device /dev/vdb1 does not exist'. This is the most likely cause given the scenario.
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 ext4 filesystem on /dev/vdb1 is corrupted.
Why it's wrong here
Filesystem corruption would produce errors like 'wrong fs type, bad option, bad superblock' or 'Input/output error' during mount, not a message that the device itself cannot be found. The error 'can't find /dev/vdb1' explicitly indicates that the kernel cannot locate the block device node, meaning the problem lies at the device level, not the filesystem level. Corruption could be present, but it is not the cause of this specific failure.
- ✗
The filesystem type specified in /etc/fstab is incorrect.
Why it's wrong here
If the filesystem type in /etc/fstab were incorrect, mount would complain with 'wrong fs type, bad option, bad superblock' or 'unknown filesystem type', not that the device is missing. Furthermore, the blkid output shows the filesystem is ext4, which matches the 'ext4' entry in fstab, so the type is already consistent. The mount failure occurs before the filesystem type is even inspected because the device node itself is absent.
- ✓
The entry for /dev/vdb1 in /etc/fstab uses a device name that does not exist.
Why this is correct
The fstab entry specifies the device path /dev/vdb1, but that block device is not present in the system (e.g., the disk was removed, or the kernel assigned a different name after a reboot). The error message 'can't find /dev/vdb1' directly states that the kernel cannot resolve that device path, which is why mount -a fails. This demonstrates a common pitfall of using static device names in fstab; using persistent identifiers like UUID= or LABEL= would avoid this issue.
- ✗
The mount point /mnt/data does not exist.
Why it's wrong here
If the mount point /mnt/data were missing, the error would explicitly say 'mount point /mnt/data does not exist' and would still attempt to look up the device. In this case, the error is about the device, not the mount point, indicating that mount fails at the device lookup stage before it ever checks the mount directory. Even if /mnt/data existed, the mount would still fail because the device itself is unavailable.
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