LFCS Storage Management Practice Question
An administrator created an LVM snapshot of a logical volume to perform a backup. During the backup, the snapshot runs out of space. What will happen to the original logical volume?
⚠ Common exam trap
Many exam-takers assume the original volume will be affected (e.g., become read-only or extended) when the snapshot runs out of space, but LVM isolates the original volume from snapshot failures, so only the snapshot is invalidated.
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 snapshot becomes invalid and must be recreated.
When an LVM snapshot runs out of space, it becomes invalid and cannot track changes made to the original logical volume during the backup. The snapshot is automatically dropped by the device-mapper, and any attempt to mount or read it will fail. The original logical volume remains fully functional and unaffected, but the snapshot must be recreated to perform a new backup.
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 original volume becomes read-only.
Why it's wrong here
When an LVM snapshot fills, the snapshot itself becomes invalid and is dropped; the origin volume continues serving reads and writes unaffected. Administrators sometimes assume origin protection, but read-only behaviour applies to full filesystems, not snapshot overflow. Snapshots exist to freeze point-in-time data for consistent backups.
- ✗
The backup completes successfully but data may be inconsistent.
Why it's wrong here
A full snapshot is marked invalid and discarded, so the backup cannot complete from it; the origin volume remains writable and unchanged. Snapshot overflow does not silently yield inconsistent data. Snapshots are designed for consistent point-in-time copies when sized adequately for the write volume during backup.
- ✓
The snapshot becomes invalid and must be recreated.
Why this is correct
LVM snapshots have a fixed size; when copy-on-write data fills it, the snapshot is marked invalid and further writes to the origin are not tracked. The original logical volume remains intact and usable, but the snapshot cannot be used for backup and must be recreated.
- ✗
The original volume is automatically extended.
Why it's wrong here
LVM never auto-extends a snapshot or its origin; when the snapshot's space is exhausted it is invalidated and removed, while the origin volume keeps operating normally. Automatic extension applies to thin pools, not classic snapshots. Snapshots suit short backup windows where change rates are predictable.
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