Mac Hard Drive Testing Tools and SMART Analysis How good is SMART (Self Monitoring Analysis and Reporting Technology) for really finding and predicting drive problems for regular hard drives and now, for SSDs.

From what I understand, different testing tools on the market report different levels of SMART levels. For example, Disk Utility, Scannerz, and SMARTReporter all seem to report what I would call a catastrophic failure level, meaning they don't report details, just, for lack of better words, "good", "maybe", and "failing" (please forgive my super high-tech terminology. :-) )

Others like smartmontools, TechTool Pro, and I think Drive Genius (not sure on that) can report a lot more detail with a lot of different parameters.

The reason I ask is this. I had a drive in my system and I was preparing to do a clean install on it of Mountain Lion. I have TechTools Pro and thought just for kicks I'd check out the SMART status on it to make sure everything was OK before reformatting the drive and doing the install. It came back and reported nothing wrong. In fact, it looked great. 

I went ahead and started doing the install, and about 20 minutes into it the thing starts tapping. If you've ever seen a drummer do one of those rhythms where they're tapping on the drum rim instead the actual drum head, that's about what it sounded like. After maybe about 30 seconds of this the thing starts screeching like crazy. The install terminated. I put an old Snow Leopard install disc into the system and boot off the DVD, and now its saying the drive is unusable and that SMART status has failed.

If I checked this drive with extensive SMART capabilities just about 45 minutes before and it reported no problems, what good is SMART testing? Since I'm considering replacing the drive with an SSD, is SMART any better on that?

Thanks.
SMART testing is of limited value in many cases, and cannot often predict failure of a hard drive. This is because different hard drive manufacturers implement different parts of the spec and (as you mentioned) different software and OS manufacturers look at different pieces of the spec in interpreting the SMART status.

Beyond that there are certain mechanical issues that can be difficult or impossible to predict. If your hard drive is tapping now, there are many things that could've caused the mechanical failure and it is hard to say if SMART had a way of knowing about it beforehand.

SSDs can and do support SMART. Rather than explaining, this Server Fault thread explains it quite well.