The authors of SoftRAID are offering a free public beta (requires registration) of SmartAlec, which monitors drive health. Essentially, it extracts the drive health monitoring features of SoftRAID.
This monitoring aspect of SoftRAID saved my bacon last year; see Even ”Enterprise Grade” Drives Fail.
Also, the DiskTester fill-volume command can be used even on in-use disks to force writing and reading of unused sectors, which can help flush out any latent issues.
Kudos to OWC for making something available for free that MPG feels ought to be an essential part of macOS: a basic version will be free in the Apple AppStore, with a more advanced version (email notifications, etc) will be available for purchase.
SMART Alec works in the background, constantly monitoring & checking your disks, and warning you if any disks are faulty, or about to fail. With SMART Alec's advanced warning, you'll have plenty of time to replace a bad disk and keep your data safe.
- PREDICTED-TO-FAIL DISK: If your disk is likely to fail in the near future you'll get a "predicted to fail" warning.
- FAILING DISK: If your disk is failing, SMART Alec will tell you right away, giving you time to replace your disk and save your data.
- TEST YOUR DISK: SMART Alec will display a green bar by all disks that are healthy. Still worried? Get SMART Alec to retest disks at any time.
- KNOW YOUR DISK: All the information about your disk is readily available and there's a disk log to track your disk's history.
- HOW RELIABLE IS MY DISK MODEL/BRAND? Opt-in to share data about your disk's reliability and performance with SMART Alec's self-learning disk failure prediction system (using predictive disk-failure analysis), and you'll get access to the most up-to-date statistics about the safest—and least safe—disks around. Plus we'll let you know how reliable the disks you're using are, and whether your data could be at risk.