Is there a HDD/Hard-Drive testing tool for mac?
Why not use Disk Utility to write zeroes or if you have more time, interest in being sure it works repeatable, set it to write more passes of random data.

The drive will report IO errors in the system.log if there are hardware errors. If you have an SSD or want a tool to read back the random bits to ensure everything not only wrote properly, but can be read back with perfect fidelity, see the free tool stressdrive written by rentzsch.

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