Lightroom Image Previews folder getting too large so I moved it, Is that safe to do?

Forum|Forum|1 year ago
January 15, 2025
1 reply
1012 views

My image previes folder for Lightroom was nearing one TB in size so taking up too much hard drive space, so I moved it to an external drive and now lightroom seems to know where it is as I can still see all of my previews with ratings. I have destroyed more lightroom catalogs in my life than I care to mention so I want to ask here before I trust this change. Does Lightroom automatically know where the image previews folder is and is it okay to have on an external drive? I've already deleted the original folder from the computer hard drive where all of my apps are. You would think that Lightroom would complain if it coudn't find the image preview folder. Can someone with more experience give me input on this please. How can I tell if Lightroom is actaully 'hooked' to the image preview folder in its new location and not just using some sort of 'memory' from the old folder. Lightroom takes knowledge to do things like this and as you can tell, it's 'seat of the pants' is how I've been gtetting along all of these years.

TIA,

Ken

macOS

Correct answer drtonyb

@Ken Nielsen

The LrC previews are stored in a folder along side your catalog file.

If you moved that folder to an external drive, LrC will not 'know' where it is. However, if the previews folder no longer exists along side your catalog, because you moved it or deleted it, then LrC will recreate the previews folder and start building new previews as required.

So, no, you can't just move the previews to somewhere else. You can delete your previews folder along with all the previews in it and LrC will simply recreate the folder and rebuild the previews as you view your photos, but they will be Standard Previews. I would not build 1:1 Previews unless you really want to scrutinise a photo; it is 1:1 Previews that take a lot of space on your hard drive. You can force a 1:1 Preview build for a single photo by Zooming to 100% in Library Loupe. However, as soon as you make a change to a photo in Develop, any 1:1 Preview that exists is invalidated and when you leave Develop, Standard Previews will be created and the old 1:1 Previews will be deleted after a few minutes.

D

drtonybCorrect answer

Legend

@Ken Nielsen

The LrC previews are stored in a folder along side your catalog file.

If you moved that folder to an external drive, LrC will not 'know' where it is. However, if the previews folder no longer exists along side your catalog, because you moved it or deleted it, then LrC will recreate the previews folder and start building new previews as required.

So, no, you can't just move the previews to somewhere else. You can delete your previews folder along with all the previews in it and LrC will simply recreate the folder and rebuild the previews as you view your photos, but they will be Standard Previews. I would not build 1:1 Previews unless you really want to scrutinise a photo; it is 1:1 Previews that take a lot of space on your hard drive. You can force a 1:1 Preview build for a single photo by Zooming to 100% in Library Loupe. However, as soon as you make a change to a photo in Develop, any 1:1 Preview that exists is invalidated and when you leave Develop, Standard Previews will be created and the old 1:1 Previews will be deleted after a few minutes.

JohanElzenga

Community Expert

To build on what @drtonyb explained: ratings have nothing to do with previews. Yes, they may be shown on the preview border, but they are stored in the catalog, so moving the previews will do nothing to ratings. Lightroom Classic has simply rebuilt those previews it needed to have, that is why you still see previews and think Lightroom Classic is still using the ones you moved. It is not, however.

P.S. Why do you act first, and then come here to ask if you did the right thing? Wouldn't the opposite order make more sense?

-- Johan W. Elzenga

Ken NielsenAuthor

Legend

Thank You. The previews folder was approaching 1TB and taking over my hard drive forcing me to delete apps. I had to dump it as even Lightroom could no longer exist with no hard drive space. I take it then that Lightroom regenerating previews will only need to regenerate what I am using and will remain small until someday in the next 30 years from now when it might become a monster and need to be dumped again?

By @Ken Nielsen

Yes, Lightroom will only generate those previews it needs, so it will take time before they grow to the same size again. Plus, there are new options now in the Catalog Settings to not let that happen. You can now set a maximum size for the previews cache.

Previews are important to me, I process a number of ways but full detail is what I need as I'm looking for best results and keep numerous versions processed with various external programs. Lightroom ends up being the hub of this processing and keeps all of the resulting images generated out of just one choice for each choice. That plus Photoshop processing means quite a bit of room is taken with previews. Thanks to everyone for help here. I'll just keep an eye on the folder and throw it out again next time it starts taking over the drive. Good to know that is an option and not destroying anything really as I take it it will be processed and restored if ever need be.

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