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OS X Topics
Physical Disk Problems
File System Problems
Bad File System?
HFS+ vs. UFS
Partitioning: an evolving topic
about: swap |
HFS vs. UFS
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Heirarchical File System
or HFS Extended |
Unix File System |
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| TLA |
HFS or HFS+ |
UFS |
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| Native to |
Mac OS |
Unix |
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| Referred to as |
Volume |
File System |
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| Organized by |
Folders |
Directories |
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| path separator |
: |
/ |
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| Sample Path |
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| HFS |
iTunes:iTunes Music:John Lee Hooker:Chill Out:Tupelo.mp3
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| UFS |
/Volumes/iTunes/iTunes Music/John Lee Hooker/Chill Out/Tupelo.mp3
|
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| Case usage |
mixed |
mixed |
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| Case SeNsitIVIty |
ignore case |
respect case |
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| Shortcuts |
Alias
Identifies disk volume and location there-on of the referenced file/folder.
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Symbolic Link
Soft: Contains the path of the target object
Hard: second directory entry for the target, must be on
the same volume.
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| Files comprised of(1) |
Two parts:
Data Fork (text, movie, image) &
Resource Fork |
Data |
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| Compatibility between Mac OS and File System |
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OS 9 Finder
Booted in OS 9 |
works fine(2) |
no access |
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OS 9 Finder/Apps
in Classic Env. under OS X |
works fine |
can access files(3) |
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| OS X / OS X Finder |
works fine |
works fine |
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| Carbonized Apps in OS X |
works fine |
works fine |
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| BSD CLI / programs in OS X |
deal with data fork only |
works fine |
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(1) Under the OS X Finder, if you copy a file from an HFS+ volume to a UFS volume, it will preserve the Resource Fork by creating two files on the UFS volume. The file visible on the UFS volume in the Finder will have the same name as the original file, the second file (containing the contents of the HFS+ Resource Fork) will have the same name with '._' prepended and will not be visible in the Finder. Similarly the OS X Finder will correctly make the HFS+ components when you instruct it to copy the file back from the UFS volume to an HFS volume. OS X does a whole bunch of work underneath the hood to map non-HFS+ file systems to present them in an HFS+ compatible manner to both Carbonized applications and to the Classic Environment under OS X.
(2) Note that RAID arrays created in OS X with Disk Utility will NOT be available when the machine is booted directly into Mac OS 9 - even if the file system on the RAID is HFS+
(3) For Classic Environment to work, the volumes from which OS X is booted and from which the Classic Environment is booted must both be HFS+. If you have no intention of booting into Classic, you may create an OS X disk image and install your working Mac OS 9 system onto the disk image.
Also note that word from development folks inside Apple indicates that OS X really does understand HFS+ and is optimized to run on HFS+, attempting to run it from a UFS volume may decrease performance slightly. |
