'Erase Free Space'

Discussion in 'Mac Basics and Help' started by DudeMartin, Mar 24, 2011.

  1. DudeMartin macrumors regular

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    Dec 2, 2010
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    Chicago, Illinois
    #1
    Hello.

    A month ago, I bought my first Mac and I am still learning about all the little neat things about OS X.

    Over the past week, I have been erasing programs that came preinstalled with Mac OS X Snow Leopard, programs like iDVD and iSync. Every time I delete stuff, I right click on the trash and hit 'Empty Trash.'

    One day, I stumbled upon a feature of 'Secure Empty Trash.' Now I have looked up what it does, but I am still not entirely sure. I did however find an article on Apple's support site that mentioned Disk Utility -> Empty Free Space.

    So I turned on Disk Utility and I clicked on my Mac OS partition, pressed 'Erase' and then pressed Erase Free Space. As I am typing it, it has about an hour and a half left to do. Now I thought that this would entirely remove every file that I ever deleted so that they cannot even be recovered later. Removing files makes me think - more disk space. Now as the Disk Utility is going, I am noticing that my available disk space is slowly becoming slower. It started with 201GB and is down to 192GB about 10 minutes later. I am confused, is this how it's supposed to work? If it is removing files, how come the available space is becoming smaller?

    Thanks in advance everyone!
     
  2. simsaladimbamba

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    #2
    Because ERASING FREE SPACE first writes zeroes to the HDD, thus reducing the available HDD capacity. After the process has been finished, the HDD capacity will be restored for you to use.
    Btw, as those applications are not really a security risk, there is no need to use ERASE FREE SPACE, as it puts unnecessary wear to the HDD. Just normally empty the Trash with files like deleted applications. If you ever need to securely delete something, you can always securely delete the Trash.
     
  3. GGJstudios macrumors Westmere

    GGJstudios

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    May 16, 2008
    #3
    Erasing free space doesn't give you more space. When you delete items and empty the Trash, the space they occupied is already freed up for use by other data. Erasing the free space simply makes recovery of deleted data impossible.
     
  4. DudeMartin thread starter macrumors regular

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    #4
    Well the Apple support site said that when you delete files using trash, they are no longer visible but the files are still there. So I figured if I erase the files entirely, to the point that they cannot be recovered, more space on the hard drive would open up?

    From the support page: "Although the disk space used by deleted files is marked as free space, deleted files remain intact until new date is written over them."
     
  5. GGJstudios macrumors Westmere

    GGJstudios

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    May 16, 2008
    #5
    1. You have 100GB of free space.
    2. You delete 2GB of files and empty the Trash.
    3. Your free space is now 102GB.
    4. You erase your free space.
    5. Your free space is still 102GB.
     
  6. Gregg2 macrumors 603

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    May 22, 2008
    Location:
    Milwaukee, WI
    #6
    No.

    I think that was data, not date. Those files could not be over written if the space were not available. Wiped space and available space count the same in terms of "free" space. Available space does not mean empty space, it means free space. GGJ explained this succinctly.
     
  7. DudeMartin thread starter macrumors regular

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    #7
    Okay, I think I got this now.

    When you delete stuff and empty trash, the computer marks it as available, that is, you can write new data in its place. When you secure erase, it removes the files entirely to the point that they cannot be recovered. Either way, the amount of available space does not change because you can't access the files once you've erased them in either situation.

    So, the Secure Erase should be used only if you deleted like important documents and don't want someone to recover them and look at them.

    Thanks guys.
     
  8. GGJstudios macrumors Westmere

    GGJstudios

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    #8
    You got it!
     
  9. Bathplug macrumors 6502a

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    #9
    I use appzapper and cleanmymac to uninstall programs and any file/folder along with it.
     
  10. simsaladimbamba

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    #10
  11. Plymouthbreezer macrumors 601

    Plymouthbreezer

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    #11
    Restart after doing an "Erase Free Space," since sometimes you get a "Disc full" error upon completion (the OS thinks you've filled your entire HD). A restart usually fixes this issue.
     
  12. GGJstudios macrumors Westmere

    GGJstudios

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    May 16, 2008
    #12
    Bad idea! AppZapper, AppCleaner, CleanApp, TrashMe, and similar apps do not do a thorough job of removing all files/folders related to deleted apps. I tested several of these, using Skype as the app to be removed. Of 17 items to be removed:
    AppZapper missed 13 items
    AppCleaner missed 11 items
    AppDelete missed 8 items
    Hazel missed 9 items​
    I also tested AppTrap, CleanMyMac and a few others, but don't recall how many items they missed. All left files/folders behind. In most cases, they remove .plist files and a few others, but leave behind much larger files and folders. (you will find a discussion of these tests in the thread linked below)

    One app that I would not recommend, based on the number of complaints that have been posted in this forum and elsewhere, is CleanMyMac. As an example: CleanMyMac cleaned too much

    The only effective method for complete app removal is manual deletion:
     
  13. Bathplug macrumors 6502a

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    Jul 12, 2010
    #13
    [/QUOTE]


    Thanks I did a couple of tests and your right, so I scrapped both appzapper and cleanmymac. Thanks

    What are your views on OnyX then? That's the only similar type of app I have left. Just looking for something to give my system a good clean once in a while which I thought cleanmymac did.
     
  14. GGJstudios macrumors Westmere

    GGJstudios

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    #14
    Onyx is fine. I rarely use it, but others have said good things about it. Really, there's nothing you need to do on a regular basis. Just use and enjoy your Mac!
     
  15. Bathplug macrumors 6502a

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    Jul 12, 2010
    #15
    Thanks.

    I'm new to mac coming from a windows xp user (didn't like vista or 7 and xp started to feel dated as newer programs wouldn't support it) so I figured I'd buy a mac. I just feel like I need to do regular maintenance with it like I did with windows but I guess not. I used to have a ton of programs to keep windows running smooth liked avg anti virus, malwarebytes, ccleaner and defragging etc plus reinstalling the os every couple months.
     
  16. GGJstudios macrumors Westmere

    GGJstudios

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    #16
    Mac OS X will be a different... but pleasant.... experience for you. You also don't have to waste time and system resources on antivirus for the Mac. There has never been a virus in the wild that runs on Mac OS X. The handful of trojans that exist can be easily avoided with some education and common sense and care in what software you install:
     
  17. Tumbleweed666 macrumors 68000

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    Mar 20, 2009
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    Near London, UK.
    #17
    If you do this, eventually you will delete something you need and cause a ton more problems than ever caused by lack of free space, especially since from what you write you don't have any problems caused by lack of free space !

    I would guess you are currently in the position of having say 200Gb of free disc and you may be getting back an extra 2 or 3Gb .. so what? If you ever get to the position you actually need that 2 or 3Gb, you'll have other issues anyway, recovering that will just put off the date you need an extra or bigger disc by a few weeks, so don't go jeopardizing your system by cleaning out minute amounts of disk space you will likely never need. Removing iDVD for example (which one day, who knows you may need) , probably gave you an extra 0.0001% disc space.

    These forums have many messages from people who screwed up their system removing what are in the bigger scheme of things tiny and unneeded amounts of disc space for some sort of unnecessary tidy compulsion reason.

    Something I learned after moving from Windows, is that Mac is for using as a computer to do stuff, whereas Windows often is used for fiddling with Windows (because thats necessary). There is no need to carry over the "fiddling with Windows" habit to Mac :D
     
  18. GGJstudios macrumors Westmere

    GGJstudios

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    #18
    This was the primary reason for my switch to Mac from Windows, and I absolutely don't miss all the "fiddling"!
     
  19. vwbeaner macrumors newbie

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    #19
    I erased the free space the other day and now my computer takes over a minute to boot up. could that have messed something up?
     
  20. simsaladimbamba

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    #20
    Maybe, how should we know? Have you deleted any system or library files/folders?

    Have you tried repairing permissions yet?
     
  21. vwbeaner macrumors newbie

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    #21
    I don't think I deleted any library files, how would I know? how do I repair permissions? I am a n00b to some of this stuff.
     
  22. simsaladimbamba

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    #22
    Using Mac OS X, how do I repair permissions, and what does that do?
    via http://www.google.com/search?q=mac repair permissions&ie=utf-8&oe=utf-8

    As you already deleted the Trash, we can't verify any deleted files or folders.
    If you have Mac OS X 10.6 Snow Leopard, you can reinstall Mac OS X without deleting your files and applications.
    Btw, why don't you use the SLEEP feature?
     
  23. Tumbleweed666 macrumors 68000

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    Mar 20, 2009
    Location:
    Near London, UK.
    #23
    Extremely unlikely. Its free space, hence its not being used, hence it should make no difference. As per the last reply, why are you booting up ?
     

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