To use Time Machine, open System Preferences > Time Machine > Select Disk, and choose your external drive. The initial backup will start, and it may take several hours, depending on the amount of data Time Machine has to copy to your external drive. Designed for Mac and ready to be used with Time Machine, the 2TB My Passport for Mac USB 3.0 Type-C External Hard Drive from WD can be used to create system backups, store your photos and videos and much more. The drive comes preformatted in HFS+ for Mac and works out of the box; simply plug the drive in and begin transferring your files quickly using the USB 3.0 port with a maximum data transfer rate of up to 5 Gb/s.

It might not be compatible. I don't know for sure, as you didn't mention whether you have one that is. Hdd formats for both mac and windows 8.

I am not trying to be a jerk, either, but I just purchased a brand new laptop with Windows 8 and I have a Toshiba automatic backup drive that is not even a year old (used with my old Vista laptop), and I can't do anything with it. It will recognize the drive one instant and then say it's not there the next.

The whole computer acted funky, like it had a virus or something (pausing up, had to right click the desktop and everything would go black and then it would refresh the entire desktop, for example).until I unplugged that danged external backup drive. Now, everything works like magic - just perfect, really. I looked all over the box and finally my eye saw one thing - Compatibility is listed on the box as NTFS formatted for XP/Vista/' and 7. I think that was my issue. I just ordered a new Toshiba Canvio and it was the only external hard drive I could find that actually said it was formatted for 8. Outlook or mail for mac.