cleaning HD empty space

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Level 1

4 points

cleaning HD empty space

I want to clean empty space on HD using Disc Utility. Tried many times after removing many files e.g. JPEG, Music, 20 GB of video files, and cleared caches. This operation takes 3 hours and just as it is finalising, a message appears "Not enough room to create a secondary temp file", and I loose the 3 hours of scanning. My HD is 500Gb SATA.

I also tried this operation with a 4GB USB drive, getting the same result. What else can I do, or better still to avoid wasting 3 hours of scanning, how much free space do I need on HD before I start.

Posted on Oct 27, 2018 3:36 AM

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Answer 1

BobHarris

Level 9

56,819 points

Oct 27, 2018 12:29 PM in response to cloonadra

The way Disk Utility erases the free space is to create a huge temp file, and writing an erase pattern into the file, until there is no free space left to give to the temp file. When it finishes, it deletes the temp file and all that space goes back to being free, but now it has an erase pattern on it, instead of your original data.

So when you get that error, you have successfully filled up your disk with a temp file overwriting all the free space.

NOTE: DO NOT Do this if you have an SSD. It will shorten the life of your SSD. Also if you have TRIM enabled, files that get deleted, have their storage collected by the SSD and it is pre-cleaned in preparation for the next write.

What you really be doing is using FileVault and then if anyone gets your Mac, they will not be able to decode the disk without your password, and all the blocks look like a random bunch of bits.

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Answer 2

cloonadra Author

Level 1

4 points

Oct 27, 2018 12:30 PM in response to BobHarris

Thank you Bob for your prompt reply. I did not understand the process, and I am so pleased that you explained it so well, because the very same thing happened when I attempted to clear a 4GB stick. I thought that there was a problem somewhere.

I am not using an SSD with Time Machine, just a HDD?? I think.

Could you just explain File Vault, I take it that its an additional App.

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Answer 3

Eric Root

Level 10

685,221 points

Oct 28, 2018 2:10 PM in response to cloonadra

FileVault 2 - About

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Answer 4

Eric Root

Level 10

685,221 points

Oct 28, 2018 2:41 PM in response to cloonadra

You are welcome. Glad to help.

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Answer 5

cloonadra Author

Level 1

4 points

Oct 28, 2018 2:15 PM in response to Eric Root

Eric much thanks for your pointer. After asking Bob about FileVault, I decided to see if it was part of my system, and I discovered it, and turned it on. It took quite a while to complete, however it was worth the time.

I just want to finalise by saying how grateful I am that you and Bob took the time to assist me in such a short space of time.

Everything appears OK now.

regards.

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cleaning HD empty space

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