Which trend is a clear warning sign before drive failure?

• A. Rising pending sectors only.
• B. CRC errors stop increasing.
• C. Rising pending sectors or reallocated sectors.
• D. Increasing spin speed.

Answer: (C)

When evaluating drive health, look for signs of sectors the drive is unable to read and has to remap. A pending sector is one the drive tried to read but couldn’t; if that read fails again, the drive will reallocate the sector to a spare area. Seeing these counts rise over time shows the disk is developing bad blocks and progressively failing to store or retrieve data reliably. If you see either a rise in pending sectors or in reallocated sectors, it’s a clear warning that failure is likely soon and you should back up data and plan a replacement.

CRC errors relate to data integrity on the data path and can be caused by issues like cables or controllers; they don’t always indicate the disk itself is failing, and a non‑increasing trend isn’t a reliable predictor. Increasing spin speed isn’t a typical indicator of impending drive failure either; RPM is usually maintained within a narrow range and isn’t used to gauge health. The combination of rising pending sectors or reallocated sectors best signals that the drive is degrading and may fail.