Backing up LRC and what does it actually save

I now have all my raw files on two seperate HD external drives…Should the new drive fail, and it is unrecoverable how would i go about  restoreing evertything?

What is the process? 

By @craig.lonie

If you connect a replacement/backup drive that has all of the same raw files on it, in exactly the same folder hierarchy as the original, then it can be a few simple steps.

1. Uncompress the .zip backup of the catalog to restore that catalog’s folder, then put it where you want it to be on your Mac (such as the Pictures folder).

2. In Lightroom Classic, in the Library module expand the Folders panel and look for the topmost parent folder  for those images; it probably is showing a question mark next to it.

3. Right-click* that folder and choose Find Missing Folder. Select the folder of the same name on the replacement volume. Lightroom Classic should re-link that folder and all images in all of its subfolders, so all of the question mark icons should go away.

4. If there is more top-level parent folder on that volume, repeat step 3 for each.

*If right-click isn’t enabled on your Mac, Control-click instead.

It backs up the entire catalog file (.lrcat), which contains edits, edit history, ratings, collections, stacks, keywords and so on.

It also backs up the .lrcat-data folder, which I believe contains all the masking you have done.

It does NOT back up your photos.

Backups are zipped, and to restore a backup, unzip it to a new folder, then double-click the catalog file to launch LrC.

For safety reasons you should back up to a different drive  – not the drive where you keep your working catalog.

You choose the location in the backup dialog. (click the Choose button)

Lightroom will only backup the catalog file (catalogname.lrcat) and the file that contains masks and AI remove (catalogname.lrcat-data), nothing else. You should use a separate backup utility to backup images and anything else you don't want to lose if your drive crashes.