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Scan a Disk for Bad Blocks

You can use terminal to check a disk for bad blocks (physically damaged areas of the disk).

First find the name of the disk, run:
diskutil list
And make a note of the disk name, eg disk8

After finding the disk name, run:
sudo fsck_hfs -fy -S /dev/DISKNAME
Enter the admin password and let the check run.

Note: This process does not guarantee that it won't make the damage worse, but this applies to all processes of this type.




I usually write a blog post about once a week. The latest post can be viewed here: Think for Yourself: In the end, everything is just an opinion. Be skeptical, and think for yourself! (posted 2026-04-25 at 21:12:02). Or go to the Home Page of My Blog to choose a post to view.

I do podcasts too! You can listen to my latest podcast, here: OJB's Podcast 2026-04-14 How Far is that Star?: How would we really know how big the universe is? Or subscribe to my podcast RSS feed, on my RSS Feeds page.

If you're not sure what to view from the thousands of pages on my site, here are some suggestions: My Latest Airshow Report (photos and movies from Warbirds Over Wanaka, 2026), My Favourite Wines and Beers (tasting notes for some of my favourites), An Interesting Astronomical Observation (learn a bit about astronomy from these observing notes), See Some Photos (A short rail journey through the Taieri Gorge), Read Some Mac Tips (Learn about how to use your Mac, and fix some problems).

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