Do you need to use your external hard drive to backup both your Mac as well as holding your Windows files or backups?
Through the use of partitioning you won’t need two separate drives, just 1 drive with two partitions.
Connect your external to your Mac and setup Time Machine to use it for backing up your Mac. The drive will be erased so make sure you’ve backed up whatever is on it already. Let the first backup complete. [Time Machine uses the HFS+ file format which Windows cannot read without 3rd party assistance.]
Now you’ll create a second partition for your Windows backups/files
- Make sure your external is plugged into your Mac
- Open Disk Utility (in Applications/Utilities)
- Select the drive and select the Partition tab
- Create a 2nd partition, formatting it as MS DOS FAT32 or leave it as “Free Space” if you want to format it as NTFS
- Eject the drive and plug it into your Windows computer and format the second partition as NTFS
NTFS vs FAT32
Need compatitbility use FAT32 or if you need to store single files larger than 4GB use NTFS.
The Mac will natively read from NTFS drives but cannot write to them without 3rd party tools.