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'Erase Free Space'

D

DudeMartin

macrumors regular
Original poster
Dec 2, 2010
240
0
Chicago, Illinois
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!
 
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.
 
DudeMartin said:
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.
Click to expand...
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.
 
GGJstudios said:
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.
Click to expand...

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."
 
DudeMartin said:
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."
Click to expand...
  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.
 
DudeMartin said:
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?
Click to expand...
No.

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."
Click to expand...
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.
 
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.
 
I use appzapper and cleanmymac to uninstall programs and any file/folder along with it.
 
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.
 
Bathplug said:
I use appzapper and cleanmymac to uninstall programs and any file/folder along with it.
Click to expand...
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:
 
simsaladimbamba said:
Best way to FULLY DELETE a program
Click to expand...
[/QUOTE]

GGJstudios said:
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:
Click to expand...


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.
 
Bathplug said:
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.
Click to expand...
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!
 
GGJstudios said:
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!
Click to expand...

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.
 
Bathplug said:
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.
Click to expand...
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:
 
Bathplug said:
Just looking for something to give my system a good clean once in a while
Click to expand...

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
 
Tumbleweed666 said:
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
Click to expand...
This was the primary reason for my switch to Mac from Windows, and I absolutely don't miss all the "fiddling"!
 
vwbeaner said:
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.
Click to expand...

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?
 
The following command is said to work in El Capitan, but will it also work in High Sierra for erasing free space?

Code: 
diskutil secureErase freespace (level 0-4) /Volumes/(Drive Name)
 
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