Earl Jarrett asks a question many people have about Time Machine backups. He’s currently using a 1TB external drive and wants to upgrade to a new 4TB drive. Time Machine can keep a deep history of your previous versions, and the more space, the deeper the history, which has led many people to upgrade the storage they allot to these bakcups.
Great article by Glenn Fleishman, and quite timely.
I have a number of hard drives for storing data and for backups. I recently realized that most of them are two or three years old. I don’t trust hard drives for very long, and I’ve been thinking about starting to replace my drives. Since I have two Time Machine backup drives, this is something I’ll need to do. Soon.
Be aware that this can take a long time.
Source: How to transfer a Time Machine backup to another backup drive | Macworld