Incomprehensible File Management

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#1
Lightroom Version
LR 6.14
Operating System
Windows 7
I am new to LR. While my understanding of how to import photos and how they can be edited is adequate for my purposes, I am at a loss comprehending the various sub-folders that appear within the Lightroom primary folder. To begin, the OS in use is Win 7 Pro. A numerous on line videos have been viewed to advanced the understanding of the file management system. However, they all appear to be Mac OS systems, which exhibit visually different files/folders than what I see on my Win 7 OS. For example, I see two folders named LR Catalog Preview. lrdata and LR Catalog Smart Previews. lrdata. Opening LR Catalog Preview.lrdata shows 10 folders - 0 thru 9 and 6 folders - A thru F. What are these folders and how are they used by LR? Opening LR Catalog Smart Previews.lrdata also show identical folders previously described. It is my understanding that these two folders, LR Catalog Previews.lrdata and LR Catalog Smart Previews.lrdata can be safely deleted. If there are members on this forum that use LR with a Win OS and would be willing to show an example of how their LR catalog appears, it would be quite helpful.
 

JohanElzenga

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#2
Just ignore this. These are support files/folders that are of no concern to the user. The Previews.lrdata folder contains the previews (the thumbnails and the loupe view). Lightroom needs those to show you the photos and the edits. Smart previews are substitutes for the originals files. You don't need to generate them on import (that is a setting you chose) unless you want to be able to edit your images while the originals are offline. On the Macintosh they look like files rather than folders, but they serve the same purpose.
 
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#3
Thanks for the response. You indicate that the Previews.lrdata are needed for the thumbnails and loupe view. I have read elsewhere that these folders/files can be deleted since they will be recreated by LR. They also can take up a large amount of disk space. Continuing to be confused by the file management system, as described the LR Catalog Previews.lrdata folder contains the 16 sub-folders with 10 having the label 0 thru 9 and 6 have the label A thru F. Opening one of these sub-folders reveals numerous other sub- folders with some containing nothing while others show data. My question is why were the folders that contain nothing in them created? Presumably, the sub-folders that contain data is related to information about a photo or photos because when clicking on the data, LR opens on a photo then reverts to the Import window. It just doesn't make any sense to me. As previously stated, the LR file management system appears to be very incomprehensible and the Adobe LR website does very little in explaining the system.
 

LRList001

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#4
Thanks for the response. You indicate that the Previews.lrdata are needed for the thumbnails and loupe view. I have read elsewhere that these folders/files can be deleted since they will be recreated by LR. They also can take up a large amount of disk space. Continuing to be confused by the file management system, as described the LR Catalog Previews.lrdata folder contains the 16 sub-folders with 10 having the label 0 thru 9 and 6 have the label A thru F. Opening one of these sub-folders reveals numerous other sub- folders with some containing nothing while others show data. My question is why were the folders that contain nothing in them created? Presumably, the sub-folders that contain data is related to information about a photo or photos because when clicking on the data, LR opens on a photo then reverts to the Import window. It just doesn't make any sense to me. As previously stated, the LR file management system appears to be very incomprehensible and the Adobe LR website does very little in explaining the system.

Just relax, let it wash over you. LR has its own way of doing things. Sure you can have a look, but you want to leave it alone. It is how LR uses some faster algorithms to go find things efficiently. Many moons ago, having a vast number of files in a single directory was a very bad idea so the writers of LR came up with this method of dividing up where they put certain files. Today having a vast number of files in a directory is less of a problem than it once was, but keeping directories small and having lots of them still has its place. The space occupied by an empty directory is so small as to be utterly irrelevant.

HTHs
 

Conrad Chavez

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#5
I think the best way to think about it is that the folder structure you see in the LR Catalog Previews.lrdata folder is set up like a cache folder, which is basically what it is. If you were to open up a cache folder for any similar application, including video and audio editors, you would find a similar directory structure that is not meant to be human-managed/readable/understandable because it’s dynamically managed as previews are generated and discarded during your editing sessions.

You probably have many other cache folders on your computer but haven't looked through them. If you were using Adobe Bridge instead of Lightroom, and dug down through the normally hidden folders to where its caches are, you'd see folder names like 2017-07-450C89BA.

As for the file sizes, it's always a good idea to assume that any serious photo/video/audio applications are going to need several GB of drive space for their caches. Trying to minimize their size may defeat their performance-enhancing purpose, if the program is forced to spend CPU time regenerating previews instead of just grabbing them from the cache.
 

LRList001

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#6
BTW, you manage the LR cache through edit>preferences>file handling (tab).
 

JohanElzenga

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#7
Thanks for the response. You indicate that the Previews.lrdata are needed for the thumbnails and loupe view. I have read elsewhere that these folders/files can be deleted since they will be recreated by LR. They also can take up a large amount of disk space. Continuing to be confused by the file management system, as described the LR Catalog Previews.lrdata folder contains the 16 sub-folders with 10 having the label 0 thru 9 and 6 have the label A thru F. Opening one of these sub-folders reveals numerous other sub- folders with some containing nothing while others show data. My question is why were the folders that contain nothing in them created? Presumably, the sub-folders that contain data is related to information about a photo or photos because when clicking on the data, LR opens on a photo then reverts to the Import window. It just doesn't make any sense to me. As previously stated, the LR file management system appears to be very incomprehensible and the Adobe LR website does very little in explaining the system.
There is no need to explain the system, because these are support folders that do not concern the user. Just leave them as they are, there is no need to open them and have a peek inside. And there is certainly no need trying to understand why Adobe has chosen to create a subfolder structure in there the way they did. Do you also go through each Windows system folder and ask yourself why Microsoft created it and what each file is supposed to do? Or do you accept that there are some files and folders on your computer that you simply leave alone?

Yes, Lightroom will recreate these folders when you delete them. But what's your point? Lightroom will recreate them because it needs them, so there is usually no reason to delete them. It will only slow Lightroom down while it recreates them.
 

clee01l

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#8
Windows uses a file/folder management system. Lightroom is an image management system that uses a database to manage images and the components needed to organize the various parts. The file ending with the suffix "lrcat" is the main database that keeps track of the images that LR manages. It keeps track of where the master image files are stored in the Windows Filesystem and the metadata associated with these images. There is another database file that manages the previews that LR requires. It is a file buried inside the folder "LR Catalog Preview. lrdata". There folders within this "lrdata" folder are created and managed by the preview database. If you drill down to the lowest folder in this "lrdata" folder, you will find a preview image file the LR needs to show the corresponding image. If this image file is not found in the Preview Database, LR will create one. Everything found in the "lrdata" folder is managed by the Preview database. (That means that you do not need to concern yourself with the contents of the "lrdata" folder and making changes in the "lrdata" folder will confuse the Previews database and LR. ). The Smart Previews "lrdata" folder is optional and is used to substitute for the master images when the disk drive containing the master images is not present OR to speed up development operations You can opt to not create Smart Previews on import to save disk space. This will require that the master image be available anytime that LR requires an image for development. This could result in slower performance when in the Develop module. Smart Previews are managed by a Smart Previews database just like regular Previews. You do not need to concern yourself with this Smart Previews "lrdata" folder either for the same reasons.

Now since LR is an image management system you can interfere with it if you attempt to use the Windows file system to manage files that the Lightroom image management system is managing. This includes the folder where the master image file are stored. Any image that you nee that is being managed by LR is available within the LR user interface. There is not need or benefit using the filesystem to access these files directly.

Lightroom uses keywords and collections to organize your images. There are powerful filters that let you quickly fins any particular image that you need. I recoment that you work in the Collection panel to organize your images and ignore the Folder panel completely. If you find yourself doing a file scan in the folder panel to find a particular image, then you are not using LR effectively. Keywords and metadata are your friends. Let them help you manage your images.
 
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#9
Thanks for the explanations. My objective for asking questions about LR's file management was not to change anything but more to understand the logic and of course comprehend why there are so many folders that do not have any content, while interspersed at certain points the folders do have content. Moreover, the folders do not appear to be in any logical order, such as sorted by date created. That is, expecting the first folder to have a date that is earlier than the next folder, etc. Of course, what I would have liked to have seen is a LR Catalog folder as it appears in Win 7 environment for comparison purposes. Most LR catalogs and their folders and files shown on websites are within a MAC OS system.
 

Jim Wilde

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#10
Of course, what I would have liked to have seen is a LR Catalog folder as it appears in Win 7 environment for comparison purposes. Most LR catalogs and their folders and files shown on websites are within a MAC OS system.
There is no difference. You can copy the catalog folder (i.e. catalog and preview caches) from Mac to Windows and vice versa, and they will function in exactly the same way. The only difference is not at the Lightroom level but is at the file system's level and that is that the preview caches are treated differently when looking at them in the file system. Mac treats the LRDATA cache as a "package", meaning that the user has to specifically select an option in Finder to "Show Package Contents", after which it will be viewable as a folder with all those sub-folders, whereas Windows treats the LRDATA cache as a folder from the outset, but it's contents would be exactly the same.
 
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