I have a late 2008 macbook 2.4 aluminum with 250 GB HD and I wanted to start using time machine.

How big of a EHD do I need.

  • Asked about:  Mac OS X 10.6 Snow Leopard

2 Answers from the Community

  • Answer

    Actually, you can use any size hard drive that is at least 20% larger than the total size of your data. But to be safe and covered up to the extent of filling your internal hard drive, you will need a 250gb or larger, hard drive to accommodate your Time Machine backup image up to the point that you have filled your internal hard drive. 500gb drives are the most economical to purchase this fall. You will need a USB drive because your MacBook does not have a firewire port. Be sure to repartition your new drive to GUID and use HFS+ Extended and Journaled formatting. Time Machine will notify you when your backup drive gets full and will inform you that backups are going to be combined and copies of deleted data are going to be removed from the backup to allow for more space to backup current data.

  • Hello.

    Quick Answer: Get a 250GB (or 320 for close to the same price)external HDD.

    Detailed Answer: Time Machine will back up all files, then continue to add to that back up. Let's say you only keep about 100GB of data on your internal drive. Time Machine would back that up, then keep adding to it as time passed, until the external is full. So the bigger the drive, the "further back in time" you can go.

    If your goal is only to have an up-to-date backup of everything, then your external drive needs to only be as large as the space you currently/plan to use on your internal.