Today’s Question: On your advice I use Time Machine to back up the internal hard drive on my computer (I also follow your other workflow for my external drives). When a Time Machine backup finishes, it shows me that the backup covers a date range from several months ago to today. I don’t understand what this date range means, and why does it only go back so far? Is this not a complete backup?
Tim’s Quick Answer: If Time Machine finished backing up successfully, you do have a complete backup. The date range you refer to indicates how far back you can go to access older versions of documents and files that have been backed up. This is one of the key advantages of a Time Machine backup.
More Detail: You can think of Time Machine as providing two key backup options, which combined cause it to be a great solution especially for backing up the primary internal hard drive on an Apple computer.
One of the core features of a Time Machine backup is that it provides a complete backup of all user files (not system files such as the operating system), and a Time Machine backup can be used to restore a computer. For example, whenever I buy a replacement computer, I perform a Time Machine backup for the existing computer, then use that backup to setup the new computer, and all my files are on the new computer just like the old computer.
The other feature of Time Machine relates to where the name “Time Machine” comes from. You can effectively go back in time to find files that had been lost, damaged, or unintentionally modified. For example, if I accidentally delete a file today and empty the trash so the file is truly lost, I can use Time Machine to go “back in time” to yesterday, where I can find the file in the location it had been saved.
Even if a file hadn’t been lost, you can use Time Machine to access older versions of files. For example, if I modified a document yesterday, but today realized that in the process I had deleted important information from the document, I could use Time Machine to recover an older version of the document to access the information I had deleted in error.
The dates shown for a Time Machine backup in System Settings indicate the farthest back you can go to find older versions of files, as well as the most recent date that a backup was completed. The available date range is dependent on how large the hard drive is and how much data you’re backing up. As the hard drive fills up, older files are discarded from the backup.
So, if you want to be able to go back further in time to find older versions of files that had been modified or deleted, you can simply use a larger hard drive for your Time Machine backup. Doing so will provide more storage space for the backup, which means more files going further into the past can be retained before the hard drive gets low on space and older backups need to be discarded.
