Everybody knows or should know by now that you should backup the catalog and the images to another drive, so if something happens, you can restore your Lightroom catalog.
If in your catalog settings, you have enabled to
Automatically write changes into XMP, you should have both the photo and the XMP sidecar. The XMP sidecar has most of the data that is stored in the Lightroom database:
- All the EXIF data about the camera/lens/photo
- All the ABOUT data: that’s the date/time, title description, location, IPTC…
- All the CRS data: the Lightroom Develop module changes. But it’s only the results of all the changes, no history. So if you took multiple crops, only the result of all the crops will be saved in the XMP sidecar.
I have found that on large catalogs, Lightroom doesn’t do “a good job” of synchronizing the changes in the database with the XMP files. So occasionally I do a:
- Select All
Save Metadata to Files
It runs at the speed of 6,000 images per hour if you do not use DNG, and at the speed of 2,000 images per hour for DNG files.
Then if you want, you can “blow your catalog” and just redo an import on a new catalog.
What you will lose by using only the XMP sidecar to re-import?
- Virtual Copies
- Flags like Pick and Reject, but ratings are included in the XMP sidecar.
- Collections (standard and smart collections)
- Develop history