Thanks!
Can you recommend an App for Mac or Win to check the integrity of my new external hard drive for example cluster and others components.
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TechTool should be able to check any drive attached to your mac.
However besides the 3 free tools of Titanium Software "Onyx", "Maintenance" and "Deeper" which I regularly use and have heard only positive comments about them, every other "tool" supposed to clean, check or improve the way your computer works usually gets at least as much negative as positive comments if you read different posts (usually the negative ones prevail)
Many people warn of "anything" supposed to pretend to make macs work "better",
In one case malware is supposed to be installed by "a certain tool" you find strongly and agessively advertised in paid banners all over the web (and even tries to install itself when you load some free things!) but that one is not TechTool.
Try TechTool (I think you can try it for free) and build your own opinion.
Someone suggested above another known tool "Drive Genius", also worth to try.
You can easily find both of them in the web.
Ed