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Measuring Fragmentation in HFS+
keyblob8K writes "Amit Singh takes a look at fragmentation in HFS+. The author provides numbers from his experiments on several HFS+ disks, and more interestingly he also provides the program he developed for this purpose. From his own limited testing, Apple's filesystem seems pretty solid in the fragmentation avoidance department. I gave hfsdebug a whirl on my 8-month-old iMac and the disk seems to be in good shape. I don't have much idea about ext2/3 or reiser, but I know that my NTFS disks are way more fragmented than this after similar amount of use."
but I know that my NTFS disks are way more fragmented than this after similar amount of use
Is this based off of instinct, actual data, or what?
A lot of people simply equate disk fragmentation with slow application execution and opening of data files. While this is the most visible effect that fragmentation has on a system, it's not the only one. If you are dealing with large files (multi track audio, video, databases) then you will get a different kind of performance hit due to the non-contiguous nature of the free space you are writing to. If you want to capture video with no dropouts, you really want a drive that has all of it's free space basically in one location. This allows you to write those large files with no physical disruption in location. Please do not think that the only benefit to unfragmented space is just "my programs launch faster". If you do any real kind of work on your system with large data files, you should know that a defragmented drive is a godsend.
Who is Twirlip of the Mists?
Are you talking about the "Optimizing System" phase? As far as I know, that updates binary-library prebindings--not fragmentation. You can read more about it here:
m an ce/Conceptual/LaunchTime/Tasks/Prebinding.html
http://developer.apple.com/documentation/Perfor
In theory, when you install anything (on any system) and have a reasonable amount of contiguous free space on your disk, the installed files should always be unfragmented since I believe that's what most file systems look for first to allocate: a large chunk of contiguous space.
Fragmentation typically occurs more when you open a file, increase its size, and write it back out. But operations that write large files to disk that do not know beforehand what the final size may also do this to some files that were only written once to your disk. For example, some of the largest fragmented files on my HFS+ volume are things snagged with BitTorrent. The fragments in these files are very regular chunks of blocks, which could be the typical 'buffer' size BT grabs when writing.