How to test External Harddrive Health?

I use Disk Drill.

Some people pay for this too, it's more comprehensive for other hardware things too: Tech Tool Pro

And also you have this other Intech SpeedTools

Edan said:

Hi,
I recently got a hold of some older external drives from storage and I wanted just to make sure that they're in good health before I start backing things up and using them...

Click to expand...

It's a good idea to test these.

Note drives have a life limit, mainly related to in-service hours. The statistics vary wide in different studies, but some say after five years of in-service life, there's a 20% chance of drive failure per year.

Like you I have used drives like this. Sometimes you don't know the history of number of usage hours. Just be aware of this.

One of the most professional and comprehensive test tools is DiskTester: http://diglloydtools.com/disktester.html

Edit/add: For Time Machine backups, there is no verification function. It's possible a bad block could later develop on the backup disk, causing a restore to fail. Your only option is periodically running Verify in Disk Utility. However this only verifies the file system. The best solution is have multiple backups of different types, such as Time Machine, Carbon Copy Cloner, etc.

I would do this for each drive:

- Connect and re-initialize to HFS+ using Disk Utility
- Run DU's "repair disk" on the disk and observe results.
- If the results indicate no problems, REPEAT THE TEST five or six times
- If the results are good after each and every test, I'd consider the drive "good to go".