Photos folder on external hard drive incessant disk usage for 5 years My photos collection has way over 500 gigabytes, and when I got a new Mac in 2015, I moved the collection to an external hard drive, and pointed Photos (iphoto by then?) to the external hard drive.
So far, so good. Everything works most of the time, with all the known glitches of Photos which are covered in many other questions.
My question is regarding disk usage. My hard drive is being used 100% of the time (and quite loudly), since 2015. The thing NEVER stops.
I have spotlight disabled for that hard drive, and the people search doesn't show anything anymore (like that &quot;X images still need to be scanned).
The processes using the hard drive are

mds
filecoordinationd (4 threads, same PID)
com.apple.MediaLibraryService (also 4 threads, 1 pid)
photolibraryd (12 threads)
cloudphotod
com.apple.CloudPhotosConfiguration (4 threads)
revisiond (4 threads).

If I kill all those processes, I end up with fseventsd in 1 thread, 28 threads of photoanalysisd, 1 thread of mds, and 4 threads of revisiond. It quiets things for a while, and the activity comes back after a while.
Why is this happening and how to fix it?
Again, this is bothering me for FIVE YEARS. It's not something temporary.
You’ve moved to a new Mac and a clean, maybe even a newer OS with newer versions of the software (iPhoto vs Photos).  There’s a lot that macOS is going to do with all those files in their new home on your external drive indexing, analyzing photos, facial recognition, etc.
These things are going to happen so you’re going to have disk activity.  Every time you kill these processes because you believe there’s an issue only delays and prolongs the process that needs to happen.  You have, as you say 500GB of files most likely with a ton of meta data attached - it’s going to take time to process them.
To draw an analogy, this is like seeing your car rev its engine a few RPM’s higher on start up than normal and rushing to the mechanic because you believe it’s a problem.  It’s not.  It’s behaving normally for the conditions which is probably much colder that day than normal and requiring more revs of the engine to warm up; sorta like having 500GB of files in a new location not normal and having to spin the drives and process them. Once everything normalizes, your car will rev down and so will your drives.