IamTheKnowledgeSeeker wrote:
Under Catalina, the internal drive is shown as the main disc (Apple SSD... in my case), a container volume and Macintosh HD and Macintosh HD - Data.
If the Mac is playing up, I tend to run First Aid on all three, but is that necessary? Or do one or more of the volumes automatically get checked if another is selected? e.g. If I First Aid Container Disk 1, does that automatically First Aid Macintosh HD and Macintosh HD - Data?
.. and as a side note, does a restart in Safe mode (Holding down shift when rebooting) perform run the same checks and fixes?
https://discussions.apple.com/content/attachment/325cc7f1-a43d-40be-99cc-976ea37cee7d
Not all three typically — just the:
Macintosh HD
and
Macintosh HD - Data
If repairs need to be done —
Boot into Recovery (Command R) and from the dropdown menu: Utilities> Disk Utility> run the First Aid on your Macintosh HD (and the "Macintosh HD-Data" volume as well if Catalina) If errors are found and repaired, run again until no errors reported.
macOS Recovery: https://support.apple.com/en-us/HT204904
I will add you can run First Aid on all volumes containers and the parent drive if you are trying to whittle down a disk issue. No harm, but usually not necessary or useful.
Safe Boot is a quick and dirty first aid repair, doing a 5-15 minute disk repair before it fully boots up, and certain system caches get cleared and rebuilt, including dynamic loader cache, etc.
https://support.apple.com/en-us/HT201262
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