Defragging a Mac? Whats the process and benefits?

Posted:
in Mac Software edited January 2014
So I want to defrag my mac and i have a couple of questions.



1. Will defragging delete any (downloaded/ bought) applications or any of my files?

2. Should I back up my all files onto an external Harddrive?

3. How do you actually defrag a mac?

4. How will it benefit me?



Thank you

Comments

  • Reply 1 of 8
    mr. memr. me Posts: 3,221member
    Defragging a Mac is strongly discouraged by Apple except in special rare circumstances. The OS handles this task automatically for you except in the rare circumstances where it is acceptable to do it yourself. Suffice it to say that there is no positive benefit to buying or using defragging software except is rare circumstances.



    As a general proposition, do not perform tasks on your computer if you do not know why you are doing them.
  • Reply 2 of 8
    mikefmikef Posts: 698member
    Windowsisms often don't carry over to OS X.



    You do not need to defrag.



    With that said, you should already be backing up all your files onto an external hard drive.
  • Reply 3 of 8
    hirohiro Posts: 2,663member
    Another confirmation for do not defrag manually.



    OS X automatically defrags files smaller than 20MB, files larger than that very rarely suffer noticeable effects from fragmentation unless your drive is too full. Then its just plain unavoidable anyway.



    Some small routinely used files also get placed in the "Hot Zone" on rotating drives, based on the device characteristics. The Hot zone reduces average seek time making access times lower for files with high access needs. If you defrag, you don't get any benefits on these small files because they are already defragged and you probably screw up the Hot Zone making your performance worse despite the supposed benefits of defragging.
  • Reply 4 of 8
    mr. memr. me Posts: 3,221member
    Quote:
    Originally Posted by Hiro View Post


    ...



    OS X automatically defrags files smaller than 20MB, files larger than that very rarely suffer noticeable effects from fragmentation unless your drive is too full. Then its just plain unavoidable anyway.



    ...



    To avoid any confusion, this is not a file fragmentation issue. You should maintain at least 10-15% of your hard drive capacity as free space. This gives your Mac's UNIX-based virtual memory system the headroom to operate.



    A Windows user might mistake a constrained virtual memory system as a symptom of file fragmentation. It is not. MacOS X runs a lot of background tasks in addition to your visible applications. Limited memory drags them to a crawl.
  • Reply 5 of 8
    hirohiro Posts: 2,663member
    Quote:
    Originally Posted by Mr. Me View Post


    To avoid any confusion, this is not a file fragmentation issue. You should maintain at least 10-15% of your hard drive capacity as free space. This gives your Mac's UNIX-based virtual memory system the headroom to operate.



    A Windows user might mistake a constrained virtual memory system as a symptom of file fragmentation. It is not. MacOS X runs a lot of background tasks in addition to your visible applications. Limited memory drags them to a crawl.



    Incorrect. It is explicitly a fragmentation issue because at those 85%+ drive full thresholds there is not enough physically contiguous space to work with so files become fragmented to fit into the existing nooks and crannies.



    I don't know why you even bring up the backing store in this context, you seem to be unaware as to how either OS reserves space for it and that that reserved space is unaffected by fragmentation issues since it was reserved contiguously to start with. Also because VM page sizes match the minimum allocatable block size, fragmentation in VM is impossible. Pages are the written elements into the backing store and you cannot fragment something that is the same size as the smallest writeable element to the drive.
  • Reply 6 of 8
    You will not loose any downloads, applications or your files by defraging your hard drive.
  • Reply 7 of 8
    hirohiro Posts: 2,663member
    At least you shouldn't, as long as there are no power interruptions, cable unpluggings or bugs in the defrag software.



    A full backup insures you against all those. But again, defrag is unnecessary and usually a bad idea in OS X. If you are working with a too full disk and want to defrag because of that, you either need a bigger drive or archive and delete some stuff.
  • Reply 8 of 8
    Quote:
    Originally Posted by uspaa View Post


    So I want to defrag my mac and i have a couple of questions.



    1. Will defragging delete any (downloaded/ bought) applications or any of my files?

    2. Should I back up my all files onto an external Harddrive?

    3. How do you actually defrag a mac?

    4. How will it benefit me?



    Thank you



    Here are your answers

    1. No, defragmentation will not delete any application or file from your Mac. It only synchronizes the memory locations of data stored in your Mac drive.

    2. If you are using a good defragmenting application then there is no need to worry about data loss. But, as precaution, you can have a storage as backup.

    3. The Apple doesn't provide any inbuilt application to defrag Mac but you can opt for a third party tool for it.

    4. Although Mac can handle the fragmentation up to 20 MB but we usually have our files greater than that. Defragmentation brings the fragments in synchronized manner and reduces the read/ write time for OS. It ultimately helps to speed up Mac performance.





    Hope my answer satisfy you
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