How can you quickly identify bad blocks on a drive?

• A. Sudo smartctl -t long /dev/sdX then review self-test log.
• B. Sudo fsck -f /dev/sdX
• C. Smartctl -c /dev/sdX
• D. Dmesg | grep disk

Answer: (A)

Using SMART self-tests to verify drive health is the most direct way to spot bad blocks. Running a SMART long self-test starts a thorough surface and read/write check of the disk without needing the filesystem to be involved, and it records detailed results in the self-test log. After the test completes, reviewing that log reveals any blocks that failed, along with their locations or counts, giving concrete evidence of bad sectors.

Other approaches miss the mark for quickly identifying bad blocks. A filesystem check focuses on filesystem integrity rather than the physical surface, so it may miss hardware-level bad blocks or behave differently depending on filesystem state. Asking SMART for capabilities or health only shows what SMART can do or the current health status; it doesn’t provide a report of actual bad blocks. And inspecting kernel messages can catch disk errors after they happen, but it isn’t a proactive or comprehensive test of the drive’s surface.