Format my drive for Mac and Windows External Disk Drives

The External Disk Drive is a fantastic piece of equipment, being small, light, robust and generally cheap for the amount of storage it gets you. Like many people I stuff mine full of files and often need to read or add to the files at different locations. That wouldn’t be a problem if all the computer operating systems could read and write to all the same file systems, but they can’t. This article will cover the options available and what you can and can’t do. It aims to help you choose the best file system to format your Portable Hard Drive.

I’ll start off with a quick lookup table which shows which operating system can read or write from which file system without using any other software. As you can see, the FAT32 filesystem is the only one that can be read from and written to by both Mac OS X and Microsoft Windows. Before you go ahead and format your Portable Hard Drive as FAT32, please read the rest of the article and consider how you intend to use your external hard disk.

System R/W FAT32 NTFS HFS+ exFAT
Mac OS X Read Yes Yes Yes Some
Write Yes No Yes Some
Windows Read Yes Yes No Some
Write Yes Yes No Some

FAT32 (File Allocation Table)

Maximum File Size: 4Gb Maximum Volume: 2TB OK so longer as performance and file size is not an issue

This filesystem works natively with both Mac OS X and Microsoft Windows operating systems. The maximum file size it can handle is 4Gb which is the smallest of the 4 filesystems mentioned in this article.

Originally designed in the 1970s, the FAT filesystem became the standard on hard disks during the DOS and Windows 9x eras that lasted about 2 decades. It has evolved over the years since it started from an 8 bit table entry and grown as hard disks became larger to where it now has 32 bits – hence FAT32. It offers reasonable performsnce, yet is simple and robust. It is supported by virtualy every operating system in existence.

So having said that, why wouldn’t you want to format your eaternal disk with it? Two main reasons are the size of the file. It can’t handle more than a 4Gb file, so is no good for database backups or storing virtual machines like I do. The performance also lags behind other filesystems, but this might not be that noticeable.

NTFS (New Technology File System)

Maximum File Size: 16Gb Maximum Volume: 256TB Great if you either don’t want to use your Mac to write data or you’re happy to spend about £13 per Mac

The NTFS filesystem can be read by Mac OS X but not written to. If you only want the MAX OS X computers to read the data, then this might be for you and if all you have is Windows then this is defineately the one to format your portable disk drive.

Even if you want to write to a NTFS formatted external drive from a Mac OS X computer, this could still be the one for you, so long as your happy to splash out a few pounds.

For about £13 you can purchase a copy of Paragon NTFS for Mac which works for versions starting with Tiger 10.7 right up to Lion 10.7. This product will work on both 32-bit and 64-bit versions of Mac OS X.

Those of you running a 32-bit version of Mac OS X can use open source products to read and write to NTFS formatted drives. All you need is NTFS-3G for Mac OS X which includes the MacFuse framework it needs to work.

You may have read that it is possible to enable native NTFS support on Snow Leopard. This is not a good idea due to stability issues. It is also worth advising that AirPort Extreme (802.11n) and Time Capsule do not support NTFS.

The NTFS filesystem was introduced for Windows NT and has been the standard for Windows 200, Windows XP and all Microsoft Windows releases since then. NTFS provides a number of improvements over FAT32 such as better performance and reliability. This is due in part to its’ use of advanced data structures which also add improved disk space utilisation, security access control lists and file system journaling.

NTFS has several improvements over FAT and HPFS (High Performance File System), such as improved support for metadata, and the use of advanced data structures to improve performance, reliability, and disk space utilization, plus additional extensions, such as security access control lists (ACL) and file system journaling.

HFS+ (Hierarchical File System Plus)

Maximum File Size: 8EiB Maximum Volume: 8EiB You must use this if you want to use the likes of Time Machine with your portable drive

This is the Mac OS X native file system. If you are going to use your external disk drive to backup your Mac using :Time Machine":http://support.apple.com/kb/HT1427 SuperDuper! or Carbon Copy Cloner then you will have to format it as HFS+. There is no alternative.

A product called MacDrive is available for about £32 that will allow your Microsoft Windows computer read your HFS+ formatted external hard drive. However if you only want to read the external disk using Windows then you can install HFSExplorer for free.

The HFS+ filesystem is also known as Mac OS Extended and replaced the previous HFS filesystem. Apple gave it the code name of Sequoia when it was in development. It contains improvements over its pre-decessor including the 65,536 allocation block limit. This meant that even on a 1Gb disk, a 1 byte file would take up 16Kb.

exFAT (Extended File Allocation Table)

Maximum File Size: 16EiB Maximum Volume: 64ZiB Can get you unstuck if you pick on the wrong version of Operating System. If you need to exchange data with a flavour of Linux then avoid like the plague

This is Microsoft Windows successor to FAT32 and is supported natively on Mac OS X 10.6.5 onwards. The Windows support is a little more complicated but does include:

The exFAT filesystem is also slower than FAT32 and takes up more memory when used. Its big advantage is the very large files it can handle, but in the world of external drives, you wouldn’t get anything that big.

Conclusions

If I was unsure just what I’d be reading and writing to, or knew there was a great variety I’d go with FAT32. This is what I’ve done with a drive I use amongst the family to transfer photos and videos between Mac OS X, Microsoft Windows and my trusty Ubuntu desk top.

Where I knew which machines I’d be moving data between, I’d go for NTFS and install the additional software on the Mac, unless I knew they could all use exFAt then that would be my choice. I have an Ubuntu desktop so wouldn’t use exFAT as that can’t read or write to it.

Of course there are other alternatives such as copy across your home Network or using services such as Google Drive, Google Docs and DropBox. The advantage of an external disk drive over these solutions is you don’t need an internet connection and they are a lot faster, and often greater capacity.

I hope you have been able to settle on the right format for your external disk drive and are very happy with your choice.