What does SMART 'Read Error Rate' track?

• A. The amount of data read per second.
• B. Time spent performing reads.
• C. Frequency of read errors — high on failing drives but vendor-specific.
• D. Error correction code efficiency during reads.

Answer: (C)

Read Error Rate in SMART measures how often read operations encounter errors. It reflects the frequency of read failures during attempts to fetch data, which tends to rise on drives that are failing or developing unreadable regions. Because manufacturers implement this metric differently, the raw values and the thresholds are vendor-specific, so what constitutes a "high" rate can vary between drives. The other options describe different aspects (throughput, time spent reading, or ECC efficiency) that aren’t what this attribute tracks. So the best fit is the frequency of read errors, with the caveat that interpretation depends on the vendor.