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how to do a disk defragment on a mac book

132923 Views 78 Replies Latest reply: Feb 27, 2014 11:38 PM by CartographerNick RSS Branched to a new discussion.
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lweileman Level 1 Level 1 (0 points)
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Jan 23, 2012 1:45 PM

How do i do a disk defragment on my mac book pro

MacBook Pro
  • OrangeMarlin Level 5 Level 5 (5,130 points)
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    Jan 23, 2012 1:53 PM (in response to lweileman)

    It's just not necessary or done on a Mac.  Some people do it (and you can find apps that help you out), but most old grizzled Mac users never do it.  Don't bother, it won't do much.

     

    Mac OS X's formatting system is quite advanced and doesn't use every nook and cranny of your hard drive.  The only time when it "might" matter is when or if your hard drive is near full, and OS X is trying to find those nooks and crannies.

     

    • Hard disk capacity is generally much greater now than a few years ago. With more free space available, the file system doesn't need to fill up every "nook and cranny." Mac OS Extended formatting (HFS Plus) avoids reusing space from deleted files as much as possible, to avoid prematurely filling small areas of recently-freed space.
    • Mac OS X 10.2 and later includes delayed allocation for Mac OS X Extended-formatted volumes. This allows a number of small allocations to be combined into a single large allocation in one area of the disk.
    • Fragmentation was often caused by continually appending data to existing files, especially with resource forks. With faster hard drives and better caching, as well as the new application packaging format, many applications simply rewrite the entire file each time. Mac OS X 10.3 Panther can also automatically defragment such slow-growing files. This process is sometimes known as "Hot-File-Adaptive-Clustering."
    • Aggressive read-ahead and write-behind caching means that minor fragmentation has less effect on perceived system performance.

     

    Message was edited by: OrangeMarlin

  • cmelbourne91 Level 1 Level 1 (35 points)
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    Jan 23, 2012 1:49 PM (in response to OrangeMarlin)

    defrags wont work on a mac, simply because it is not a computer. This is a PC process, and wont help the mac in any way, due to the processing system and the lack of background processes that occur. a defrag wont help you, the only way to try and imitate it, is to trawl through the mac syastem looking over your files.

  • andyandywells Level 1 Level 1 (105 points)
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    Jan 23, 2012 1:50 PM (in response to lweileman)

    Mac defragments automatically and it is unecessary to do so. It will have no effect.

  • OrangeMarlin Level 5 Level 5 (5,130 points)
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    Jan 23, 2012 1:51 PM (in response to cmelbourne91)

    cmelbourne91 wrote:

     

    defrags wont work on a mac, simply because it is not a computer.

     

    Really?  Not a computer?  What is it?  A car?  A coffee maker?  A politician?  I'm confused.

  • Allan Eckert Level 8 Level 8 (39,335 points)
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    Jan 23, 2012 1:56 PM (in response to OrangeMarlin)

    I like that one about a politician. Cute.

     

    I like to see him dig himself out of that hole because he certainly come across as knowing nothing at all with that comment.

     

    Allan

  • cmelbourne91 Level 1 Level 1 (35 points)
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    Jan 23, 2012 1:56 PM (in response to Allan Eckert)

    I meant the processing system is nothing like a computer, its not a PC, if you look through Mac history it has always been seperate from PC's. Dont be so narrow minded.

  • OrangeMarlin Level 5 Level 5 (5,130 points)
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    Jan 23, 2012 1:58 PM (in response to Allan Eckert)

    Allan Eckert wrote:

     

    I like that one about a politician. Cute.

     

    I like to see him ddig himself out of that hole because he certainly come across as knowing nothing at all with that comment.

     

    Allan

    We'll see.  He might never return.

     

    It's hard not to be snarky around here, but seriously, it sounded like a troll comment.  You know, PC's are real computers, but Macs are just toys. 

  • eww Level 9 Level 9 (52,975 points)
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    Jan 23, 2012 1:58 PM (in response to lweileman)

    Here is a detaled rundown on what defragmenting does and doesn't do and when it is and isn't needed on a Mac:

     

    http://www.macattorney.com/ts.html#6

  • OrangeMarlin Level 5 Level 5 (5,130 points)
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    Jan 23, 2012 1:59 PM (in response to cmelbourne91)

    cmelbourne91 wrote:

     

    I meant the processing system is nothing like a computer, its not a PC, if you look through Mac history it has always been seperate from PC's. Dont be so narrow minded.

    Wow, I didn't know that.  I guess because I didn't buy my first Mac until 1984, I'm unfamiliar with its history.  Sorry to be so dense. 

  • Shootist007 Level 6 Level 6 (16,640 points)
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    Jan 23, 2012 2:16 PM (in response to eww)

    eww wrote:

     

    Here is a detaled rundown on what defragmenting does and doesn't do and when it is and isn't needed on a Mac:

     

    http://www.macattorney.com/ts.html#6

    Thanks eww for posting that link.

    Although the Mac file system does not Fragment files like the Windows file system does that does not mean some routine mantenance wouldn't help.

    As explained in the link post by eww a defragging program can help move all files into a closer area of the drive giving a larger free space area for the operating system to work with.

    Does it need to done on a scheduled basis or done as files are written like on a Windows PC? No. But it is not a bad Idea to do it every now and then. I have done it with no ill effects. The one thing you don't want to do is run it on a SSD just like you don't defragment SSDs on a Win PC.

  • James O\\\'Brien Level 1 Level 1 (15 points)
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    Jan 23, 2012 2:54 PM (in response to cmelbourne91)

    According to cmelbourne91, only pc's are computers.  Everything else is "not a PC and therefore not a computer."  Good logic.  Therefore the million of linux servers that the internet runs on aren't computers, nor is the cray super-computer.  Cmelbourne91 I know computer history - I starting programming the 8086 intel processor running MS/DOS in assembly language.  Having run various flavors of windows and linux over the years it is my personal opinion that Apple has the finest operating system (since OSX came out).  Also cmelbourne91 apple uses the same processor and system bus and graphics cards that your beloved PCs use.

     

    As for the real question - I concur that Mac OSX maintains and optimizes the disk.  I've run a macbook for years without fragmentation or slowing.  There is a disk-utility if you want, and if you really need a clean disk for video processing Mac OSX has tools to copy to a clean external drive, boot off that drive, wipe your hard drive, and copy back.  Voila.

  • noondaywitch Level 6 Level 6 (8,130 points)
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    Jan 23, 2012 3:09 PM (in response to lweileman)

    The question hasn't yet been asked; why do you feel you need to defrag? Do you work with multi-GB audio or video files?

    Are you experiencing slowing down of the system? If yes to that one, defragging is probably the least useful thing you'll need to do.

     

    If you really, really, feel the need, James' final comment is the best and safest method. Clone the entire HD to an external HD, boot from the external and use DU to erase the Macintosh HD then clone the system back to the Macintosh HD.

     

    Result - a freshly written copy of all your stuff in fully defragmented form.

    Bonus - you now have a bootable back-up drive (which everyone ought to have anyway).

  • OrangeMarlin Level 5 Level 5 (5,130 points)
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    Jan 23, 2012 3:47 PM (in response to noondaywitch)

    Not exactly easy.  I used to do that back in the ancient days of OS 1 - 9.

  • noondaywitch Level 6 Level 6 (8,130 points)
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    Jan 23, 2012 4:43 PM (in response to OrangeMarlin)

    I didn't have external drives back then.

     

    Nothing difficult about cloning a drive. Certainly safer than many defrag programmes, most of which only defrag files, not the free space, so their effectiveness is limited.

     

    But unless you're handling large audio or movie files, or possibly raw images, you're more likely to run out of disk space before there's any significant fragmentation.

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