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Too many previews and smart previews - switching off & deleting?

Joined
Sep 30, 2018
Messages
3
Lightroom Experience
Intermediate
Lightroom Version
Cloud Service
Lightroom Version
Lightroom Classic version: 7.5 [ 1186149 ]
Operating System
Windows 10
Hi all

I'm very much an amateur and casual user of LR Classic on a Win 10 lap-top. I only shoot in jpg format. I have a collection of approx 40,000 photos. I started using LR Classic about 2 years ago. My Lightroom Catalog is named Catalog-2.

My problem is that my hard disc is being swamped with previews and smart previews. In LR folder there are very large two sub-folders with enormous numbers of files:
Lightroom Catalog-2 Previews.lrdata with 47 Gb and 53,000 files
Lightroom Catalog-2 Smart Previews.lrdata with 26 Gb data and 36,000 files

As you can see I have a greater number of smart previews + previews than photos! I suspect that I've switched on advanced options which are creating previews & smart previews. Two questions:
1. How do I change settings to minimize/switch off previews / smart previews?
2. How do I safely delete the unwanted previews & smart previews?

Thank you
 
Joined
Jul 2, 2015
Messages
10,121
Location
Netherlands
Lightroom Experience
Power User
Lightroom Version
Ignore the number of files in those folders. Lightroom Catalog-2 Previews.lrdata contains the previews that you are actually looking at when you work in Lightroom. Lightroom stores edits in the catalog as a kind of 'to do list' and does not change the originals, so in order to see the edits that you have applied, you are looking at a preview. Lightroom would rebuild them if you deleted them.

You probably don't need those smart previews at all. Smart previews are small substitutes for the original files, so you can work in Lightroom even when the originals are offline (for example because you've stored them on an external disk and that disk is not connected right now). If you never work that way, then turn off the building of smart previews on import and delete the entire Lightroom Catalog-2 Smart Previews.lrdata folder.
 
Joined
Feb 1, 2010
Messages
12,416
Location
West Sussex, UK
Lightroom Experience
Advanced
Lightroom Version
You can't stop Lightroom building previews (if you didn't have previews, there's be nothing to see in the Library module, as that only shows previews). You can delete the previews folder, but Lightroom will immediately create a new one which will initially be a lot smaller but it will replace the lost previews automatically as the images are brought into the grid or filmstrip....so over time the size of the previews cache will increase again. You can also manage the size of the previews cache to some extent via the settings in the File Handling tab of the Catalog Settings menu. Discarding 1:1 previews after a certain time period is one obvious area, as would changing the size and quality of the standard previews (but here you're trading lower space utilisation against the user experience in the Library module).

Smart Previews are only built when you expressly request them. I'd guess you are building them automatically during import (see the check boxes in the File Handling tab in the right-hand panel of the Import screen). If you don't need them, don't build them. You can discard existing smart previews (Library menu>Previews>Discard Smart Previews) or simply delete the Smart Previews cache.
 
Joined
Sep 30, 2018
Messages
3
Lightroom Experience
Intermediate
Lightroom Version
Cloud Service
Thank you Johan and Jim for the hugely helpful explanations. I will take your advice and switch off smart previews.
 
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