Defragmentation in Mac OS X


One of the first reactions to your system acting slow is to defragment your hard disk. If you ask Windows users, they will tell you that they have done it for years (about once a month is recommend) so that’s what comes naturally.

Regarding Mac users wanting to defragment their hard disk but not being able to find it even after searching in the Disk Utility shouldn’t be concerned

It is normal to be concerned about your disk fragmentation because performance will suffer as a result, however, Apple not providing a defragmentation tool is not an oversight because any version of OS X later than 10.2 can automatically manage defragmentation by preventing file fragmentation in the first place by doing the following
  • The file system looks for the largest free areas on the hard disk to allow large file to be located without being divided (fragmented)
  • Small files will be collected into a group and will be moved to a larger area on the hard disk, the process of moving these files will defragment them because of the previous point that writing files will be as defragmented as possible
  • When a file is frequently accessed but not modified, they will be moved to a special area on the hard disk which has the fastest access (again the process of moving these files will automatically defragment them)
  • When a file has become exceedingly fragmented, the operating system will defragment it on the spot
With all these factors at play it seem pointless to manually defragment your hard disk (to me it is actually a waste of time), however, there is one exception that weakens the operating system’s ability to manage its own fragmentation and that is when the amount of free space on the hard disk is less than 10 percent. A simple remedy to the problem is copying the data to another hard disk, wiping the fragmented drive, then copy the files back (single writing new data will always be unfragmented)
If you are really desperate for manually defragmenting your hard disk, you can use a third party tool like Mac tool like Stellar defrag drive
You may also refer to for more information
Do YOU defragment your Mac hard drive? If so, what tools do you use? Where they useful or just a waste of time?
Feel free to leave comments stating your experience with disk fragmentation

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7 Responses to Defragmentation in Mac OS X

  1. Raphael Love says:

    Currently, I do defrag using Idefrag – I dont feel the need to do it very often. However because I have a very large applications folder over time I do notice that there is a system impact. That impact is quite improved post a defrag run.

  2. Pingback: Mac Defrag Disk Cleanup

    • Alena says:

      i’ve heard this time after time, they do need to be defragged, just not often, when a file is bitty on an ssd, intsaed of making 1 i/o operation, it has to make 2 i/o operations to find the record or though many times it is bitty, either way if you defrag or not, the ssd shoud last long enough to the point where the ssd your using now is outdated or your pc dies

  3. Stuart Bell says:

    I have an HDD not an SSD. So, I was recommended to defrag my Mac. I had to choices iDefarg and Stellar Drive Defrag.
    Features- Both have the same features
    Price- Stellar Drive defrag is cheaper

    I bought the app from

  4. dumois says:

    Stellar Drive Defrag is a distinct fraud. I paid for the program and never, ever, was able to make it work. “Support” at Stellar keeps asking you questions to never reply a valid answer. These crooks should be in jail, not stealing money from honest people.

  5. Additionally, those thinking of purchasing Stellar’s product might want to see this:

  6. Drew says:

    This software doesn’t work. Worked with their support people for hours trying to get it to work. Then after many hours and no luck, they refused to give me a refund.

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