Should I replace a drive with bad sectors?

The answer depends on how many, and whether the count is stable or growing: a handful of stable remapped sectors is routine; a rising count is a failing drive.

Monitor

A small, unchanging Reallocated Sector Count that has held steady for months is common as drives age. Keep it under observation, make sure your backups run, and you do not need to rush a replacement.

Replace

Replace the drive if any of these are true:

• Reallocated sectors are climbing over days or weeks.
• There are Current Pending Sectors that persist or grow.
• An Extended SMART test fails.
• The drive is throwing read errors, dropping out of the array, or making unusual noises.

In a RAID array, lean toward replacing

A suspect drive in a redundant array is not an immediate data-loss risk, but it quietly spends your safety margin: if it fails during a rebuild of another drive, you can lose the pool. Because a replacement is cheap relative to the data, replace proactively once the trend turns bad rather than waiting for outright failure. Use a same-or-larger CMR NAS drive; the table lists current options.