15 Replies Latest reply on Jun 18, 2016 8:31 AM by joshuaw85675092

    Can't reduce previews.lrdata size

    ntompson

      Hi all,

       

      My Previews.lrdata folder is 45 GB. On a 500 GB SSD (late 2013 15" retina MacBook Pro), this is a reasonable chunk.

       

      So I've gone through and used the "discard 1:1 previews..." menu item on all photos that I don't expect to edit again. Somewhat to my surprise, the Previews.lrdata folder has not changed in file size by 1 byte. I've used the "optimise catalog" option, but that didn't seem to do anything either.

       

      I'd prefer not to flush the entire preview cache by deleting Previews.lrdata, as for recent photos that I haven't edited yet I appreciate having the 1:1 previews pre-rendered.

       

      Am I expecting too much here? Should there not be a relationship between me discarding 1:1 previews and a reduction in the Previews.lrdata folder size?

       

      Thanks,


      Nick

        • 1. Re: Can't reduce previews.lrdata size
          D.A.R Adobe Community Professional

          There is a relationship but the change you expect (actually I did too) often does not show immediately. I dont recall why but I did read and understand that the value will show a reduction after shut down and restarting of your machine.

          • 2. Re: Can't reduce previews.lrdata size
            areohbee Level 5

            My experience: discard 1:1 previews feature is broken, again (it was broken for a while, then fixed for a while, now seems broken again).

             

            Or, maybe they just changed how it works (cleaning up only upon restart) - dunno.

             

            I know smart previews are only cleaned up upon restart (if > 1 hour has elapsed), but I thought regular 1:1 previews were immediate, they used to be anyway..

            • 3. Re: Can't reduce previews.lrdata size
              D.A.R Adobe Community Professional

              Just tested an immediate restart. No significant difference. So either it is really broken again or the time delay is in effect.

              We'll see in the morning.

              • 4. Re: Can't reduce previews.lrdata size
                ntompson Level 1

                Thanks David and Rob for your quick replies.

                 

                Just tried to restart my machine and it made no difference. Like you say looks like it is either broken or on some kind of odd time delay.

                 

                It's quite annoying really - big chunk of space that I can't easily manage.

                 

                I'll let you know if anything changes.

                 

                Nick

                • 5. Re: Can't reduce previews.lrdata size
                  johnrellis Most Valuable Participant

                  You may already know about this: According to this post, a 1:1 preview will not be discarded unless the width of the standard-sized preview chosen in Catalog Settings is less than half the width of the 1:1 preview.

                   

                  For example, I tried this on a catalog in which I had perhaps a couple hundred 1:1 previews of images that were 5472 x 3648.   When Catalog Settings > Standard Preview Size = 2880, then Discard 1:1 Previews did not change the size of Previews.lrdata.  Presumably this was because 2880 is greater than half the full image size (5472 / 2 = 2736).  But when I changed Standard Preview Size to 2048, which is less than half the full image width, Discard 1:1 Previews then reduced the size of Previews.lrdata by many gigabytes.

                  • 6. Re: Can't reduce previews.lrdata size
                    D.A.R Adobe Community Professional

                    An overnight test:

                     

                    I had a preview file of 5.74GB. I created 1500 1:1 Previews bringing that up to 10.32GB.

                    I deleted the 1:1 Previews and shut down for the night. Today the preview file appeared the same initially, then after a few minutes working (not using Lightroom) it dropped to 6.17GB.

                    My standard preview size is set to 1024. The 1:1 were a mix of 5184px, 5616,  3546 on the long edges.

                     

                    Why it didn't reduce to the original 5.74 I don't know but it did reduce.

                    • 7. Re: Can't reduce previews.lrdata size
                      ntompson Level 1

                      Thanks for the update. Still no improvement for me 1 restart / 1 night later / a few open / close Lightroom.

                       

                      John's comment may well be the answer... my standard sized preview is 2800 (fits the 15" rMBP) and my camera is 16 MP (4928 on the long edge). Standard preview is more than half the size of the 1:1 preview so - by the post John references - the 1:1 previews won't be purged even though I have explicitly discarded them.

                       

                      If this is the answer, this is pretty dumb stuff. Of course I want my standard sized preview set to 2800 - what else would I do on my 15" rMBP (an ideal machine for photo editing)? OK, 16 MP is not cutting edge these days, but it could at least be called "typical". There is no command to discard standard previews... so this would mean that my previews.lrdata will only ever expand over time.

                       

                      Not a good look.

                       

                      It would be nice if Adobe had something to say about this...

                       

                      Nick

                      • 8. Re: Can't reduce previews.lrdata size
                        D.A.R Adobe Community Professional
                        Of course I want my standard sized preview set to 2800 - what else would I do on my 15" rMBP

                         

                        Try 2048. After all there are panels left and right of the image. Even if you close one of them theres probably 280 pixels being used for that.

                        Discarding standard previews makes no sense. Every time you used the Loupe view it would continually be building a new preview. That would seriously impact performance.

                         

                        Currently to reduce the size of your preview file you could simply delete it after changing the standard preview size and allow Lightroom to rebuild the previews.

                        • 9. Re: Can't reduce previews.lrdata size
                          ntompson Level 1

                          Thanks David but that doesn't really help.

                           

                          For photos that I am still in the process of editing, I want the full size preview - I use the full screen view to help with filtering images and to check final edits etc. I wouldn't want to have an inferior preview for the full screen preview.

                           

                          On the other hand, for older photos that are in my catalogue, but for which I have finished editing, I really don't need to keep the previews. I will only look at them through Lightroom occasionally, and I don't mind a small amount of lag for the preview to render on the fly on the odd occasion that I do.

                           

                          I don't want to have to break apart my catalogue to separate old from new: that really diminishes the value of Lightroom's great library capabilities.

                           

                          For the sake of managing SSD space, I will at some point move my older photos off to a NAS, but will still keep them in the catalogue. OK, I get the RAW file space back, but it seems that I'll never be able to reclaim any space in the ever growing previews cache.

                           

                          This really seems like a significant weakness.

                          • 10. Re: Can't reduce previews.lrdata size
                            areohbee Level 5

                            ntompson wrote:

                             

                            Thanks David but that doesn't really help.

                            Not sure if you are referring to David's suggestion #1 (try 2048) or suggestion #2: delete all previews.

                            I think it would help to reduce standard preview size.

                             

                            ntompson wrote:

                             

                            For photos that I am still in the process of editing, I want the full size preview - I use the full screen view to help with filtering images and to check final edits etc. I wouldn't want to have an inferior preview for the full screen preview.

                            Lightroom will use the 1:1 preview for this.

                             

                            Summary: I *think* reducing standard preview size will be just what the doctor ordered for you - but, I'd love for you to prove me wrong..

                             

                            R

                            • 11. Re: Can't reduce previews.lrdata size
                              D.A.R Adobe Community Professional

                              Im not suggesting you use an inferior preview. You can build a 1:1 at any time.

                               

                              The suggestion was to reduce the "standard" size previews, albeit by a little, to determine if the previously suggested math is correct (IE - 1:1s are not discarded unless the standards are less than half of the original dimensions)

                              • 12. Re: Can't reduce previews.lrdata size
                                areohbee Level 5

                                John R. Ellis wrote:

                                 

                                You may already know about this: According to this post, a 1:1 preview will not be discarded unless the width of the standard-sized preview chosen in Catalog Settings is less than half the width of the 1:1 preview.

                                I did not know that (although given what I know about the preview subsystem, it's no surprise) - thank you. I retested discarding 1:1 previews after dropping standard preview size and it worked just dandy (and immediately) - not broken after all.

                                 

                                Thanks again John .

                                 

                                Rob

                                • 13. Re: Can't reduce previews.lrdata size
                                  ntompson Level 1

                                  Ah that's interesting David, Rob.

                                   

                                  So if I reduce the size of the standard preview to below screen resolution, then Lightroom just uses (down-scales) the 1:1 preview...

                                   

                                  Are there any disadvantages to this? If not, why have a standard preview at all? Would I better off be setting the standard preview to the smallest possible size?

                                   

                                  I'll certainly try this, although am a little reluctant until I've got a better idea of what might happen... which prompts a question: when I make the standard preview size change in Lightroom, does it then invalidate all of the standard previews in my catalogue? Does it have to crank through and regenerate all the standard previews at the new size?

                                   

                                  Thanks for your speedy and useful help so far.

                                   

                                  Nick

                                  • 14. Re: Can't reduce previews.lrdata size
                                    areohbee Level 5

                                    ntompson wrote:

                                     

                                    So if I reduce the size of the standard preview to below screen resolution, then Lightroom just uses (down-scales) the 1:1 preview...

                                    That is correct.

                                     

                                    ntompson wrote:

                                     

                                    Are there any disadvantages to this?

                                    No - your standard previews were set too high before.

                                     

                                    ntompson wrote:

                                     

                                    why have a standard preview at all?

                                    For performance reasons - faster to grab/resize a smaller preview if it will do.

                                     

                                    ntompson wrote:

                                     

                                    Would I better off be setting the standard preview to the smallest possible size?

                                    No. If you do that, then Lr will re-render a 1:1 preview for fit view, even if a standard preview was already available (since it would be too small). Granted, if the 1:1 preview was already available, it wouldn't need to re-render it, but if you're expiring them, it might not be available, and even so, it takes longer to load/resize a larger preview than a smaller one.

                                     

                                    ntompson wrote:

                                     

                                    when I make the standard preview size change in Lightroom, does it then invalidate all of the standard previews in my catalogue? Does it have to crank through and regenerate all the standard previews at the new size?

                                    No, and no (but in my opinion, user should be prompted for whether he/she would like to rebuild when size or quality changes).

                                     

                                    In many cases, the difference in having too small a setting or too large a setting, will be almost (or completely) inconsequential. To be honest, I'm surprised Adobe exposed this option to the user, since most users don't have a clue what an optimal setting should be. If I were Adobe, I'd assume Lr/main-UI was gonna be on the biggest monitor, and automatically size previews accordingly. Often when I mention this, people point out that the same catalog might also be used on a laptop, at which point previews would no longer be optimal, and there are other dual-monitor considerations.., but hey - whatever...

                                     

                                    PS - Lightroom creates (up to) 7 different preview sizes: from 1:1 to tiny thumb. When it creates a big preview (1:1 or standard), it creates all smaller previews too, by halfening the size. Such is very fast, and no doubt accounts for the reason it won't discard 1:1 if next one down (standard) would be greater than half it's size (it's actually only creating 6 previews in that case - 1:1 through thumb, there is no big standard preview of the size you specified in that case , or if you prefer another way of looking at it: the 1:1 preview is your largest standard preview ).

                                     

                                    If you want to better understand what's stored for previews, you can play with the PreviewExporter plugin I wrote (free) - it allows you to specify which level (1-7) preview you want to export, and if you enable verbose logging it will provide info about what was available, and which level of preview was exported. Here is an excerpt from "post-process action" (export-filter) UI:

                                    _preview_exporter_excerpt_sizes.gif

                                    Cheers,

                                    Rob

                                    1 person found this helpful
                                    • 15. Re: Can't reduce previews.lrdata size
                                      joshuaw85675092

                                      Hi guys, I've gone into the previews.lrdata package and deleted a bunch of the oldest folders but the package file itself remains the same size.

                                      Is there a way to force finder to refresh the file size? Or does the package need to be resized, similar to how a sparsebundle works? Thanks for any help you can give.