Kind of borderline not an Unraid question... hope this is okay with the mods:

 

At work we are upgrading our server to all new hardware and will be replacing all of the aging hard drives. I'd like to run a really good test on all the drives before throwing all of our (mission critical) data on them. I was thinking of throwing them in an unRAID server and preclearing them all before forging ahead to seed out any bad apples. Obviously they would end up being formatted NTFS before using them on Windows. Would this be a reasonable idea?

The drive manufacturers have diagnostics that will run on Windows free for downloading and those would work just as well for testing and possibly be more convenient.

Western Digital's Data Lifeguard would work, and runs on Windows.