Site TIPS PAGE🔎   UP ONE LEVEL
 OJB's Site. v2.4.L: tip80 tips mac owen2 
Tip

Discuss   Up to OJB's Mac Tips List

Bad Block Scan from Terminal

How to do a bad block scan of a volume.

This reads the whole disk and reports any (hardware) errors found.

List available disks: diskutil list
Find the ID of volume to be scanned in the list, eg /dev/disk2

Enter this: sudo fsck_hfs -dylS DISKID
Example: sudo fsck_hfs -dylS /dev/disk2s2

Meaning of options...
d = output debugging info
y = assume a yes response to all questions
l = live fsck (lock down and test-only)
S = Scan disk for bad blocks




My latest blog post: Think for Yourself: In the end, everything is just an opinion. Be skeptical, and think for yourself! (posted 2026-04-25).

My latest podcast: OJB's Podcast 2026-04-14 How Far is that Star?

If you're not sure what to view from my site, here are some suggestions: My Latest Airshow Report, My Favourite Wines and Beers, An Interesting Astronomical Observation, See Some Photos, Read Some Mac Tips.

Site News (Mobile): OJB's web site, v 2.4 which has major changes, and possibly errors! Please report anything to ojb@mac.com.