Publishers of technology books, eBooks, and videos for creative people

Home > Articles > Apple > Operating Systems

  • Print
  • + Share This
Like this article? We recommend

When Time Machine Backs Up

Following the initial backup, Time Machine will perform a backup every hour that data that has changed (referred to as an incremental backup). Hourly backups are great because it means that Time Machine can offer several recent versions of a document that you are working with on any given day. Also, if you need to recover from a disaster, you will have incredibly recent copies of your files available, which means you stand to lose very little (if any) information.

While Time Machine performs hourly backups, it only keeps them for 24 hours. At midnight, Time Machine selects the most recent hourly backup and designates it as a daily backup. These daily backups are maintained for a month. This strikes a very good balance between having backups as current as possible and keeping the storage needs for backups down.

For backups that are more than a month old, Time Machine maintains a weekly backup so long as there is space on your backup drive. When you start running out of space, Time Machine will warn you and delete older backups. In selecting which backups to delete, Time Machine uses a formula designed to preserve the most actual data that it can rather than simply deleting the oldest backups.

If your designated backup drive is not connected to your computer (as is often the case with portable Macs), Time Machine will perform a backup as soon as the drive is connected and available. It is a good idea to connect your backup drive to your computer at least once a day to ensure backups are kept relatively current.

  • + Share This
  • 🔖 Save To Your Account