Pref files are best left on the fast internal drive as with the application. The pref files are quite small so there is nothing to be gained in moving them. On my system they are:
Lightroom 6 Preferences.agprefs (95kb)
Lightroom 6 Startup Preferences.agprefs (2kb)
The entire LR folder containing prefs, presets and templates etc is only 6mb
If you want to save space, keep all images on the external drive and move the catalog including previews from the Pictures folder to the external drive. But bear in mind that LR will then only work whilst the external drive is connected.
The monthly subscription to the Photography Plan includes a small amount of cloud storage with the option to purchase extra. If using LR Mobile on the iPhone or iPad, the smart previews generated in the cloud do not count towards your storage limit, so are effectively unlimited for synchronizing.
Backup the catalog every time you finish editing and quit Lightroom, and keep a copy.
Backup your images separately using Time Machine or any backup software of your choice.
Yes, you can create your workflow where in you can keep all your images on the external hard drive and the Lightroom catalog file as well.
If you are just getting started with Lightroom then use the Destination location as your external hard drive when you import your image from the external source like Camera/SD Card.
If you already have your Images on the Mac HD drive, then Move all your Image to the external hard drive first and then import the images straight from there.
Lastly you can change the Lightroom Catalog location as well.
Default Location : Pictures folder on the Mac HD Drive, there's folder called Lightroom which you can move to the external drive too ( however Lightroom catalog will not take much storage space as its only import the previews for the images not the actual and complete image)
Once you move the Lightroom Catalog file to the external hard drive, then you need to browse the catalog file when you launch Lightroom only once.
Refer thread: Moving LR catalog to external hard drive
Let us know if it helps.
Thank you Mohit!
I just moved the Lightroom folder to the external drive and choose the catalog while restarting again.
My WHOLE PHOTO LIBARY is now a catalog file, but inmy library there are only 3 photosI i imported as the default LIghtroom catalog.
What is the difference from a catalog, library and preview mode on Lightroom?
Any video tutorials?
Lightroom Catalog is the file where all the Preview, edits, keywords get saved, in the another words whatever you do in the Lightroom that gets saved in the Catalog file.
Refer the below link for the detailed information.