Once a week or maybe less frequently, I back up the LR catalog. I was surprised that all the old backups are retained, and that the size of the back ups are substantial. I tried to delete a couple older back ups, and the next time I restarted LightRoom, it couldn't find many of the photos. I had to restore the computer to the week before I deleted the old back ups, even though I was able to restore the back up files I had deleted. Is it supposed to be safe to delete old back ups? These redundant files take up space I could be using for photos. Thanks!!