Lightroom: Lrcat File & Lrdata Folders

I have 3 catalogs in Lightroom: wip, that’s my Work In Progress, syv, that’s the catalog for my finalized photos and work is the catalog for work paid or to be paid. Lightroom created 3 folders:

1. syv
2. wip
3. work

Why go through all the gory details of the files and folders? Once you know what’s there, you will be able to solve many of your own problems:

• Backups
• Restores
• Computer moves
• Folders/Directory moves

You will be able to make your own decision without having to listen to what somebody else says.

Let’s analyze the syv folder, the wip and the work folder will have the same structure. The syv folder contains another syv folder. The second syv folder contains 2 more folders and 1 file:

Name	Type
Backups	Folder
syv Previews.lrdata	Folder
syv.lrcat	File

Backups

Lightroom creates a folder with the name date & time in the format YYYY-MM-DD HHMM and the folder only contains 1 file: the copy of the catalog as of that date and time.

If you are running out of disk space, you can delete your older backups. Never the last 2 or 3 catalogs.

Previews.lrdata

The Previews.lrdata folder contains 16 folders 0 thru F. That’s 0 to 15 in hexadecimal: Why hexadecimal instead of the regular decimal system? Computers love using hexadecimal: base 16, because it’s simpler to count for computers, it’s a power of 2. 2x2 = 4, 4x2 = 8, 8x2 = 16. Each folder in turn can have as many as 4096 folders. If you are not lost yet, each folder has only 1 file with a nice friendly name of: 0AC186B8-BF5B-4E54-BC7B-693672DE08F7-dec9c97cfdba51ec0d0316335c5f1941-5.lr-preview.noindex.

1. The Previews.lrdata folder contains all your previews, whatever size.
2. Adobe designed this folders arrangement to equalize distribution and speed-up reads and writes.
3. This data is expendable. Meaning you can even delete it, Lightroom will rebuild it.

lrcat

The syv.lrcat is the actual Lightroom catalog. It contains all the metadata, the history, the collections, the flags, the crops, all the adjustments… If you are not using the XMP sidecars, that’s the only place where your changes to the photo, including the IPTC data, are stored.

That’s the one file that Lightroom backs-up when you exit Lightroom.

1. Nowhere in this, do we find the actual photos. They are where you decided to store them.
2. When Lightroom close, it does ask you if you want to backup your catalog (depending on what is your Lightroom backup settings: every time, every day, every week, or next time). Lightroom doesn’t ask you to backup your photos.
3. You will have to backup your photos separately.