[v5, v6] Why does it take so long to overwrite free space?

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[v5, v6] Why does it take so long to overwrite free space?

Postby Overwriter » Tue Dec 23, 2008 2:51 pm

When you use Eraser to overwrite a file Eraser actually has to write the same amount of data as the target file size. This means that if you overwrite a 1GB file Eraser has to write 1GB to overwrite it. However this is only true if you select a single pass, should a user select the Gutmann method for example to overwrite a 1GB file Eraser has to write 35GB as the Gutmann method requires a 35 pass with various patterns.

So, when you overwrite your free space think about how much free space there actually is. It could be huge with modern hard drives. If you do have a lot of free space and you wish to overwrite it I personally recommend a single pseudorandom pass with Eraser, as far as I know there as never been any successful recovery of overwritten data on a modern hard drive after a single pseudorandom pass.

If you have a very large hard drive and wish to overwrite your free space regularly I suggest you make some “ballast” files to occupy the free space so there is less for Eraser to wipe. When you need more space on your drive simply delete one of your “ballast” files and continue.
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Re: Why does Eraser take so long to overwrite my free space ?

Postby greyowl » Fri Dec 26, 2008 8:53 pm

Thanks for the explanation.

How do you make a ballast file?
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Re: Why does Eraser take so long to overwrite my free space ?

Postby Overwriter » Fri Dec 26, 2008 9:29 pm

Hi greyowl

You can make a ballast file out of anything you like really. Perhaps you have some DVD films you could use to make backups and store them on your hard drive.

I personally prefer to make Truecrypt file volumes because I can make them exactly the size I want. You could make some bulky 10 – 20 GB ones to take up most of the free space and then make some smaller 1GB ones for fine tuning the amount of free space you wish to have available.

I did make a feature request for this feature to be added to Eraser V6. The ability to make random files of a user specific size just for this purpose but there seemed to be little support for it.
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Re: Why does Eraser take so long to overwrite my free space ?

Postby greyowl » Fri Dec 26, 2008 10:12 pm

Thanks for the explanation.

I presume that after creating a Truecrypt file you can remove it in the future to provide needed space.
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Re: Why does Eraser take so long to overwrite my free space ?

Postby Overwriter » Fri Dec 26, 2008 10:58 pm

greyowl wrote:Thanks for the explanation.

I presume that after creating a Truecrypt file you can remove it in the future to provide needed space.


Yes you can. :)
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Re: [v5, v6] Why does it take so long to overwrite free space?

Postby hewag100609 » Wed Jun 10, 2009 1:08 am

Very clean...
thanks overwriter...
regards
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Re: [v5, v6] Why does it take so long to overwrite free space?

Postby philnok » Thu Sep 24, 2009 6:35 pm

This may be a bit faster than a TrueCrypt volume.

dummy12.rar
(24.15 KiB) Downloaded 385 times


http://www.mynikko.com/dummy/
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Re: [v5, v6] Why does it take so long to overwrite free space?

Postby Joel » Sat Sep 26, 2009 12:00 pm

It replicates what Eraser does on an unused space erase without cluster tips being erased; Eraser however is more secure as directory entries are erased (for NTFS, and FAT under XP), though yes that application is useful for creating a ballast file.

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Re: [v5, v6] Why does it take so long to overwrite free space?

Postby Unregistered » Fri Oct 09, 2009 10:04 am

What about partitioning instead of ballast files? If I have a huge harddisk (1-2TB) which takes 20 hours to erase, wouldn't it be better to split the HD into smaller partitions, so one day I can erase the first partition, next day the second... and so on?
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Re: [v5, v6] Why does it take so long to overwrite free space?

Postby Joel » Sat Oct 10, 2009 12:02 am

that works. But ballast files allow you to grow your partition in the event you run out of space. Also not everyone is familiar with the process of repartitioning.

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Re: [v5, v6] Why does it take so long to overwrite free spac

Postby seglea » Thu Jan 19, 2012 1:39 pm

How long is long? Mine's been running for over 12 hours now, trying to wipe a half-empty 80Gb disk on a 6-year old Pentium 4 - is this normal, or has it jammed somewhere?
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Re: [v5, v6] Why does it take so long to overwrite free spac

Postby Joel » Sun Jan 22, 2012 3:43 am

What does it say for progress when you double-click on the running task?
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Re: [v5, v6] Why does it take so long to overwrite free spac

Postby mrmagic » Sun Jul 01, 2012 1:12 pm

my unused disk space erase has been running for 48 hours. Progress says: 90%, pass 3 of 3 Old resident system table files. Should I cancel the erase?
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Re: [v5, v6] Why does it take so long to overwrite free spac

Postby Joel » Sun Jul 01, 2012 1:14 pm

How much disk space do you have left?
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Re: [v5, v6] Why does it take so long to overwrite free spac

Postby mrmagic » Sun Jul 01, 2012 2:13 pm

drive is 585 gig, with 15 gig free space
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