Fragmentation on external HD

Discussion in 'Mac Basics and Help' started by dogbone, Apr 20, 2006.

  1. dogbone macrumors 68020

    dogbone

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    #1
    OK I know that mac is sort of fragment proof and one need not worry about it. But what's the story when using an external drive to back up? Does one have to defrag it regularly?
     
  2. Eniregnat macrumors 68000

    Eniregnat

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    #2
    No not if it is in HFS+ format. If your using a any of the FATs or NTFS (to a lesser extent) you will need to defrag. I think UFS is as as good as HFS.
     
  3. dogbone thread starter macrumors 68020

    dogbone

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    #3
    Thanks, but why is that.

    Does OSX perform cron scripts on connected drives? Because didn't OS9 use HFS+?
     
  4. Eniregnat macrumors 68000

    Eniregnat

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    #4
    This Apple article is a good start, though it basically states "You don't need to defrag, and don't worry about it."

    Aside from what Apple notes, it is really a function of how the disk writes clusters of information. OS X does everything it can to not immediately use space that is freed up. This does several things, aside from make data scavenging and reclamation easier. It speeds disk use (arguably) and it helps prevent fragmentation. The older MS FAT system (which is is still usable and efficient for many purposes) fragments, because it writes clusters all over the place. Under FAT, as soon as a small amount of space is free, it is likely filled by the os. There are a number of reasons behind this, and people often vilify FAT, but works for many applications.

    Ok, I am getting a little tangential here. Basicly, it comes down to two things. 1.) The system is much more efficient at writing information to the disk so that it can be accessed quickly. 2.) A misperception as to what efficient is and what fragmentation is and does to a systems performance.

    DiskWarrior and will and can defragment OS X. Surprisingly for me, only the volumes that I use for editing were fragmented. These programs do a lot more than just defragment, they can actually take the information that is used more often, and "move" it so that that it is more efficiently placed on the drive, and this may not mean that the files are contiguous.

    By the way, this lack of needing to be defragmented isn't exclusive to OS X, there are UNIX systems that I would say are as good. And, I would bet that MS is attempting to make Vista much better at allocating disk space and not grenade scattering information.
     

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