Preview file handling is broken. "Discard 1:1 previews after 1 day" and still 100GB+ Previews.lrdata Folder

[cdog1977]

Yes, I am a power user of lightroom with an absurd # of photos. But as far as I can tell, the only solution to an exploding Previews.lrdata folder is to delete the folder entirely which I am loathe to do, as I'm not 100% sure it won't break some functionality. I have no issues with waiting for new previews to be built, I have issues with no in-software way to manage this problem. I'm on the latest version of CC Classic, 8.1 (Dec 2018).

1. Adobe, you need to fix Lightroom so that Previews.lrdata can be set to a maximum size (e.g., 50GB), and when it hits the cap, previews start being automatically deleted with the oldest ones going in the bin first.

2. Can someone from Adobe confirm that I can just delete the folder? Is deleting the "official fix?"

[JohanElzenga]

There is nothing broken with the preview handling. A preview contains a pyramid of sizes, from thumbnail size to loupe view size. These are needed and will not be discarded, because that is what you see when you look at your images in Lightroom. If you didn't have these previews, then Lightroom would have to render them for each page of thumbnails you are viewing and each image you view in any kind of loupe view. Don't think lightly about that. It takes about one second for a preview to be rendered, so if your grid shows 30 thumbnails per view, then it would take half a minute to render each grid. Quickly going through a few hundred images to find a particular image would become a nightmare. It would take up to 10 minutes to find an image among 600 thumbnails...

The 1:1 size previews are the only ones you can discard (automatically or manually), because they are only needed when you zoom in to 100%. Because you don't do that for each image you are looking at, you can trade speed for drive space with these previews. You can delete the entire preview cache, but as soon as you use Lightroom it will start to rebuild those previews that you are looking at, so this is only a temporary solution and it would indeed cause this massive slow down at the start.

By the way: 100+ GB for 'an absurd # of photos' is nothing special. My catalog contains about 180,000 images and my preview cache is  almost 300 GB.

[cdog1977]

I guess we have to agree to disagree Johan, I don't need to have a preview for every single image in my catalog, as I've already culled and processed the vast majority of them and turned them into JPEGs. I have previews from before LR allowed you to use the OOC JPEG as the preview - I'd be happy to discard those previews. Furthermore, previews on my workstation generate faster than 1 sec, but perhaps that's because I'm using an SSD - hence the storage concern.

Thanks for your input.

[JohanElzenga]

My point was that nothing is 'broken' with the handling of previews. Lightroom performs as intended, and the size of the cache is understandable if you understand the preview pyramid structure. Of course that doesn't mean that you have to like how it works or that you are not permitted to use a different workflow than intended, but that is another matter.

The whole idea behind Lightroom is that you do not convert images to RGB copies (let alone JPEG copies) after you have finished editing them. You do that only when you need such a copy and delete this copy after you've used it. That's because you can export a new copy (often with different settings) when you need another copy. In such a workflow it makes sense not to delete your previews.

I agree that Adobe could have added an option to also delete the loupe-sized previews. In most cases when I need a copy of an older image I simply select it in the grid and then export it. I don't need to see it in loupe view to know this is the image I want. BTW, the speed that previews are rendered is mainly depending on the speed of the drive your images are on and the size of the images (I shoot 42 MP images), not the drive the previews are on.

[Just Shoot Me · Accepted solution]

Just Delete the Previews folder. Close LR, open the File Manager for the OS you are using, Delete the Previews folder.

Next time you open LR the previews folder will be recreated and only the images you browse in the grid view area and in the film strip will new previews be created.

I normally delete the previews folder once it gets above 20GBs in size.