Can I free up drive space by removing previews and cache?

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#1
Hello,

I’m trying to free up space on my HD. My LR catalog is 1.5 GB, my smart previews are 26 GB, and my Preview Cache is 41 GB.

I don’t feel I need the cache, nor the smart previews or even 1:1 Previews but I’ve read conflicting information on Adobe’s site about the advisability of messing with the files, at least as I interpret their postings: “Do not touch the Catalog Previews.LRDATA folder, except to delete entirely- only if there is corruption problems.”

Curiously, I’ve had the ‘Automatically Discard 1:1 Previews’ set to 30 days and just this morning I reset it to ‘After One Day’ then closed and opened LR but there was no reduction in file sizes.

Is there a ‘proper’ and/or safe way to remove these as a practical matter?

Thanks much,
Dan
 

JohanElzenga

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#2
You do need the previews cache. That is what you look at when you look at the grid, and that is what you look at when you view an image. If you delete that cache, Lightroom will rebuild it.

You do not need smart previews, unless you want to edit images while the originals are offline.
 

Dan Marchant

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#3
As Johan says you can safely delete the previews folder but as soon as you start editing again LR will start to recreate Preview. So any gain will be temporary.

It is also important to understand that the size of the cache and the previews have a big impact on Lightroom performance. As mentioned deleted previews will need to be rebuilt if those images are edited again. Also setting a smaller cache size in the Preferences may also have a negative effect on LR speed when in the develop module.
 

JohanElzenga

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#4
As Johan says you can safely delete the previews folder but as soon as you start editing again LR will start to recreate Preview.
Even earlier than that. As soon as you view an image (even if it's just as a thumbnail in the grid!) Lightroom will have to re-render the preview. The preview used in the Develop module is actually a different preview, stored in the Camera Raw cache.
 

Gnits

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#5
There are a few cache settings in the preferences under file handling....

upload_2017-7-24_11-52-58.png


You can also select to discard 1:1 previews in the Library / Previews memnu options.

upload_2017-7-24_11-53-28.png
 

Jimmsp

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What size is your HD, and how full is it? You might clear up more space by buying a new external HD, call it something like "History" (as I do), and move a lot of older photos from your current HD to a folder on "History" called "Photo History". That will clear up a lot of space on your internal HD, and probably even increase the performance of LR.
If your older folders are in large chunks (folders) by years, LR can move them one at a time.
 
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Hello and thank you for your replies!
It's been over a year and I have the same issue. I came here, searched for the problem, and voila! I found my own thread with the same question!

So frustrating... (Using Win 10) I go to Library -> Previews -> Discard 1:1 & Smart previews, watch to progress bar 'delete' them and then check the folder sizes and they're still 69GB & 22GB!
Why?
I hate messing with the folder contents, and I don't think I should need to with what I have done, but if that is my only option what exactly do I delete? There seem to be two sub-directories based on hexadecimal naming. Delete those? Will they be rebuild as needed? The files themselves seem to all be DNG's. Delete only those?
Your wisdom will be greatly appreciated.
 

Jim Wilde

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#9
The problem is that the answers that you received last time are also still the same. Yes, you can stop using Smart Previews (delete the yourcatalogname Smart Previews.lrdata folder), and you can delete the entire Library Previews as well (yourcatalogname Previews.lrdata)....but as explained above the latter folder will be immediately recreated, and while it will be initially very small it will over time increase in size. So that's a temporary fix, a permanent fix would be increasing the size of the disk drive that you store your catalog and previews on.
 
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Hello Jim and others who have taken the time to offer help.

Jim, I failed to share a few important points in my most recent post:
  • I agree that extra hard drive space is a great solution, except…
  • My hardware includes an internal SSD drive that contains LR & PS, the catalog, and the photos I’m actively editing and many external drives for bulk storage.
  • My workflow includes moving the files I no longer need for active editing from the SSD to external hard drives, many TBs of them. This includes the raw photos, the finished exports, and copies of the catalog backups. (It is actually my wife that needs convincing of the need for all these external drives!)
Before I posted, I found myself in a unique position. I was done editing all photos and thought I’d do some housekeeping. That is when I noticed that I still have previews that are 10 months old even though I had the “Automatically Discard 1:1 Previews” set to “after 30 days.” I then reset the setting to “After One Day,” closed LR (with backup & optimization), and reopened. Previews still there…
Puzzled, frustrated, and curious, I did the Library -> Previews -> Discard as described in yesterday’s post with no change.
While I still have photos on the SSD now, they are already backed up on the external drives, and most importantly for this discussion, I am done editing them so I have no need for previews; not of these photos, not of any of the photos that LR has ever “seen.” I want to start clean, and ideally, I’m trying to figure out:
  • Why is LR keeping previews long after the specified time set in preferences?
  • Why didn’t the manual Library -> Previews -> Discard 1:1 & Smart previews process work even though there was an apparent indication by the progress bar?
I guess my “big picture issue” is that while I could add hard drive space to hold all the previews that I don’t need, I think the better solution is to get LR to work the way it is designed to work by having it delete the previews that are no longer needed.

I may be left with the work-around of simply deleting the two folders as you suggested Jim. I’m just wondering why LR isn’t working. Kind of like how I like my car to work as it’s supposed to, not have to lift to hood and monkey with things.

Thanks again for everyone’s suggestions!
screenshot.jpg
 

Jim Wilde

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#11
Let's talk about Smart Previews first. What do you use them for, i.e. the simple solution to the problem of the space they take up is not to create them in the first place. If you do really need them, do you need them for all your files? When you discard them, what option are you taking, i.e. discarding only the selected images, or for ALL your files? If the latter, I don't think there's an immediate deletion, I think it happens more gradually....so the simple thing to do after the "discard all" command would be to close Lightroom then delete the Smart Previews.lrdata folder.

Library Previews: do you understand what an individual preview file is? Each individual preview file is actually a "pyramid" containing multiple different-sized jpegs previews of the image. IIRC, there can be up to 7 different sizes of previews with 1:1 obviously being the largest. But when you discard a 1:1 preview, only that portion of the preview file is discarded, the other sizes are retained. Another thing to bear in mind is that every time you edit an image, the existing library preview file is removed (because it's now out of date following the edit) and a new standard preview (not a 1:1 preview) will be created the next time you access the image. All this means is that when you "discard 1:1 previews" there may not actually be that many to discard. Unless you have the discard option set to "Never", in all probability the 1:1 previews would likely take up a very small percentage of the overall previews folder size.

Basically, Lightroom is operating as designed, but if disk space is an issue it's imperative that you understand how the system is meant to work. Only then can you start thinking about strategies for controlling the size of the previews libraries. One thing you could also consider is why you are keeping images on an SSD....there is very very little performance advantage in doing so, so perhaps there are space gains to be had there.

If I was in your position I'd be asking myself "do I need smart previews", and "do I need to keep images on the SSD"? I'd also consider deleting the main Previews.lrdata folder, which would give you a lot of space back, but then you need to understand that if you have images that you don't need to view then keep them that way....even if you just start scrolling through the grid, any image that appears in that Grid will have a full standard-sized preview silently built for it.
 
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#12
Jim,
Thank you very much for your detailed and helpful response!
I had a major ah-ha moment this morning. I spent some time chatting with adobe and I learned the following (Maybe I should say the following is my understanding. I’m sure there are a few details that are not quite correct.):
  • The Library -> Previews -> Discard option is designed to be used only on selected photos. (I had forgotten that I had done so in the past.) It will not work to delete all previews as I was trying to do, see below.
  • Not only do the images need to be selected, but the raw photos need to be on a drive and linked so that LR can access them or the database would get corrupted. Put another way, if there are previews displayed and those are selected without the photos being linked, the previews will remain.
In the end, I did delete the two folders, Smart Previews.lrdata & Previews.lrdata, as you suggested.
Finally, I got my questions answered (mostly).
Thank you for your valuable contribution!
Dan Poiree
 
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