Hard drives set up for use on Windows machines only will often use NTFS, while Macs will use HFS+. That said, if you are using both a PC and Mac in the workflow, you’ll need to use a different format.
You may wish to use an external FireWire or USB hard drive to store your Aperture Library, referenced images, or Vaults. Here are some suggestions on preparing the external hard drive for best performance with Aperture. Many external hard drives come pre-formatted as FAT 32. This is a native Windows file format that can be read by Mac OS X, but is not ideal for use with Aperture.
Before you begin to use your new external hard drive with Aperture, reformat it to the Mac OS Extended file system:
Be sure your drive is attached and mounted.
If you have already written any data to the drive, back it up before proceeding to the next step.
In the Finder, choose Go > Utilities. The /Applications/Utilities folder will open.
Launch Disk Utility.
Click the icon for your external hard drive in the sidebar on the left.
Click the Erase tab along the top of the window.
From the Volume Format menu, choose Mac OS Extended (Journaled).
Enter a name for the external hard drive in the Name field.
Click the Erase button.
In Disk Utility on your Mac, you can format an external disk for a Windows computer.
WARNING: Formatting a disk or volume erases all the files on it. Save any files you need to another volume before formatting.
In the Disk Utility app on your Mac, choose View > Show All Devices.
In the sidebar, select the disk you want to format to use with Windows computers.
Click the Erase button .
Click the Scheme pop-up menu, then choose Master Boot Record.
Click the Format pop-up menu, then choose one of the following:
MS-DOS (FAT): Choose this format if the size of the disk is 32 GB or less.
ExFAT: Choose this format if the size of the disk is over 32 GB.
Enter a name for the volume.
The maximum length for the volume name is 11 characters.
Click Erase, then click Done.
You can also partition a disk using the Master Boot Record partition layout, which is compatible with Windows.
See alsoFile system formats available in Disk Utility on MacPartition schemes available in Disk Utility on Mac