I'm considering buying a second-hand HDD and want to know what to look for before committing. How can I check its previous usage and health, what tests should I run, and what are the realistic risks or limitations of using a used drive?
3 Answers
Use a SMART viewer such as CrystalDiskInfo to check power-on hours, start/stop counts, temperatures, reallocated sectors, pending sectors, and other warning values. CrystalDiskMark can also give you a basic performance check, although it isn’t a reliability test.
For a used drive, I’d run the SMART short test first, review the result, and then run the extended or long test to scan the entire disk surface. If the drive is empty and you’re comfortable erasing it, a destructive write-and-read test such as badblocks can provide a more thorough check. Review SMART data again afterward and watch for newly appearing reallocated or pending sectors.
Treat any used HDD as a drive that could fail tomorrow. Don’t store anything irreplaceable on it without a separate backup. Age alone isn’t an absolute dealbreaker—older enterprise drives can be reasonable in a NAS with redundancy and monitoring—but RAID or parity only helps with drive failure and does not replace a real backup. For a single-drive setup, choosing a newer drive with low hours is the safer option.

That makes sense. I’ll use the drive only for noncritical data unless I have an independent backup, and I won’t rely on mirroring or parity as my only protection.