Formatting a Portable Hard Drive for Both Mac and PC

Do you need to use a portable hard drive to move files between a Mac and PC. There are some things you need to know. My son called me this morning with just this problem. He had taken a large number of photos at a recent company function, and had edited them on his Mac at home. He used his external hard drive from work to copy his photos, but when he dragged the photos to the drive, they would not write. So he called Tech Support (that would be me).

After a few questions, I learned that the hard drive had been formatted on his Windows PC at work. The drive was formatted NTFS, and that is why his Mac could read the drive, but not write to it. To understand the problem, and the solution, I need to give you a brief tutorial on drive formats and file systems.

To use any drive, you must format it to hold data. When you format, you need to choose a file system. Fortunately, there are only a few file systems in common use. Modern Windows computers use NTFS (the NT file system, first used on Windows NT). Windows computers running XP, Vista, Windows 7, and soon, Windows 8 (and of course Windows NT) can read and write to NTFS formatted drives. Macintosh computers can read an NTFS drive, but they cannot write to one.

Macintosh computers have used HFS+ (Hierarchical File System Plus) since OS 8 back in 1998. Of course, all modern Macs can read and write to NTFS+ formatted drives, but Windows computers can neither read nor write to one.

So is there a format that we can use so that both Windows and Macs machines read and write? It turns out that there is. Prior to NTFS, Windows machines used an older file format called FAT32 (File Allocation Table, 32 bit). An older standard, FAT32 is slower than NTFS and HFS+, but it is quite reliable and robust. Its major limitation is that it cannot store files larger than 4 GB. But that's not much of a limitation. With the exception of video files, and perhaps some other large graphics files, your are not likely to have many files that large.

So where do you get a FAT32 formatted drive? You make it yourself! Just reformat an existing drive. To format a drive in Windows, go to Control Panel/Admin Tools/Computer Management/Disk Management. Identify the drive that you want to format, right click on it, and select Format. Give the drive a name, and change the File System in the pop up window from NTFS to FAT32. On a Mac, go to your Applications folder, open the Utilities folder, and launch Disk Utility. Locate your drive in the left hand panel, then click on it. In the right hand panel, click the Erase Button. Change the format to MS-Dos FAT (this is Fat 32) and click Erase. IMPORTANT: Reformatting the drive will erase all of the data on the drive.

Your newly reformatted drive can now be used on your Windows machines, Mac, and as an added bonus, your FAT32 drive can be read on Linux computers as well.