Today’s Question: A question about the answer regarding where to store Lightroom Classic catalog. Can one keep the catalog on the internal drive but have a copy on the external where the photos are stored too—not working in the one with the photos on the external but just storing a copy there?
Tim’s Quick Answer: Yes, you can keep an additional backup copy of your Lightroom Classic catalog anywhere you’d like. Just be sure not to accidentally open a backup catalog in place of your master catalog.
More Detail: Since the Lightroom Classic catalog contains considerable information about your photos, including metadata updates, adjustments, and more, you naturally want to make sure you keep your catalog safe. That means, among other things, making sure you maintain a good backup copy of the catalog.
I do recommend using the built-in catalog backup feature in Lightroom Classic to create backup copies, in part because it includes options to check the catalog integrity and to optimize the catalog to improve performance. But regardless of how you are backing up your catalog, you can store that backup anywhere you’d like.
First and foremost, of course, you want to store the catalog backup on a hard drive other than the drive the catalog is on. That is so that if the hard drive fails you don’t lose both the master catalog and backup copies. So, if the catalog is on the internal hard drive, backing up to an external hard drive makes perfect sense.
You can also copy the catalog to a cloud-based storage solution, such as Dropbox, or by using an online backup service such as Backblaze (https://timgrey.me/onlinebackup), which is what I use and recommend for a cloud-based backup solution.