Mac OS X Choosing UFS or Mac OS Extended (HFS Plus) formatting
Summary
This article highlights some UFS and Mac OS Extended (HFS Plus) format differences and discusses Mac OS Standard (HFS) compatibility; use Mac OS Extended if you are unsure which is best for you.
When you install Mac OS X you can choose to optionally erase and format a hard disk or volume using the Mac OS Extended (HFS Plus), Mac OS Extended Journaled or UFS (UNIX File System) format. (In some cases you may be required to erase the selected volume.) Unless you have a specific reason to use UFS, you should use the Mac OS Extended and Mac OS Extended Journaled format since it provides a more familiar experience to Macintosh users.
Products Affected
Mac OS installation/setup (any version)
Mac OS Extended and Mac OS Extended Journaled is case-preserving
If a volume is formatted using the Mac OS Extended and Mac OS Extended Journaled format, you cannot have two files in the same location (the same folder or directory) with the same name--even if the case varies, such as "My File" and "my file".
UFS is case-sensitive
With a UFS-formatted volume, you may have the two "My File" files in the same location as well as other similarly named files -- "My file," "MY file," "My FiLe," "my File," and so forth.
AirPort and UFS
AirPort does not function when Mac OS X is installed on a UFS formatted volume. For more information, please see article 106252: "Mac OS X 10.0: AirPort Does Not Work From UFS Partition"
Customizing Hard Disk Volume Name
You can permanently customize a hard disk volume name when using Mac OS Extended, but not (currently) when using a UFS-formatted hard disk volume. For more information, please see article 106191: "Mac OS X 10.0: Startup Volume Is Named '/' Instead of 'Mac OS X'"
Mac OS X Classic Environment and UFS
The Mac OS X Classic environment does not function the first time it is opened on a UFS formatted volume. For more information, please see article 106277: "Mac OS X 10.0: Classic Does Not Work From a UFS Disk On First Use"
Mac OS 9 and UFS
When you start up your computer using Mac OS 9.x, UFS hard disk volumes do not appear on the desktop and cannot be used.
UFS With UNIX
UFS may be preferable for developing UNIX-based applications within Mac OS X.
Type/Creator File Association
Associating a type of file with a particular application (by use of type/creator information) is not available with UFS-formatted systems. For more information, please see article 55381: "Mac OS: File Type and Creator Codes, and File Formats"
For detailed information on the file systems and file handling, see the documentation provided in the Mac OS X System Overview at:
About Mac OS Standard (HFS) and Mac OS X
Although Mac OS X recognizes Mac OS Standard (HFS) format volumes, Mac OS X cannot be installed on a Mac OS Standard (HFS)-formatted volume. If you format a Mac OS Standard volume during Mac OS X installation all information on your volume will be erased, and only Mac OS X will be present when the process is complete.
If you need to use a Mac OS Standard-formatted volume as well as Mac OS X on a single hard disk, you must first back up and partition the hard disk. After important documents and data have been backed up, start up from a Mac OS 9.1 disc, open Drive Setup 1.8.1 to partition the hard disk, then create a Mac OS Standard partition. Format at least one partition as Mac OS Extended and Mac OS Extended Journaled for Mac OS X with a minimum size of 1.5 GB.
Additional Information
Important: Partitioning your hard disk erases all information on it. Back up important data and documents to a different hard disk or network volume before partitioning the hard disk.
Note: Do not use Drive Setup 1.8.1 to create a UFS partition. For more information, please see article 106229: "Mac OS X 10.0: Does Not Recognize and Cannot Be Installed On UFS Disks Formatted by Drive Setup 1.8.1"
Mac OS Standard is not a modern file system specification. Mac OS Extended and Mac OS Extended Journaled is modern, and much more efficient. For more information on the differences between Mac OS Extended and Mac OS Extended Journaled format and Mac OS Standard format see the following articles:
Article 8647: "Macintosh: File System Specifications and Terms"
Article 25557: "Mac OS X: Mac OS Extended Format - Volume and File Limits"
Ultra2 LVD SCSI cards
Some Power Macintosh G3 (Blue and White) and Macintosh Server G3 (Blue and White) shipped with a single- or dual-channel Ultra2 LVD SCSI card. You may encounter errors installing Mac OS X onto a UFS-formatted drive connected to one of these cards. Use Mac OS Extended (HFS Plus) and Mac OS Extended Journaled when installing Mac OS X onto such a drive.