Time to erase free disc space

[jberaser]

When erasing files and folders I use the 35 pass option. With a folder containing 1 gb of files it takes an hour or more, which is fine.

But what happens if I'm erasing free disc space? Can I also expect it to take an hour or so per gig of free space, or would it be faster? If I have 60 gb of free space that would be a lengthy erase at 60-70 hours. As well, I'd be concerned about the health of my drive/cpu running for that task for that length of time.

Regards,

JB

 

[Robbie]

I have C: Drive of 70.7GB, usually with about 61GB of free space, as I don't store much on the computer. Running a 1 pass pseudorandom (PNRG) wipe on free space takes about 30 mins for the cluster tips (ie to wipe the cluster tips of about 9.5 to 10GB of files) and 1 hour or so for the free space wipe (of about 61GB), ie 1.5 hours in total.

A 4 pass PRNG takes about 4.75 hours, again about one hour per pass and about 45 mins for the cluster tip wipes.

The most I ever did was an 8 pass PRNG which took over 9 hours.

A 35 pass, using Gutmann would take, I calculate, about 40 hours+ - I would never do this pass anyway (see below) but it's far too long, in my view, to subject my hard drive to being in (literally) constant use. However, many people have done this, with no problem.

In my view, a 35 pass run is overkill. From all the reports I have read, a 1 pass using PRNG is sufficient. A 3 pass (either using PRNG or the 3 pass US DOD choice in Eraser) is more than sufficient and even my once-a-month choice of a 4 pass PRNG is probably over the top. The one time I did an 8 pass I felt like it was far too much. I have also ran the 7 pass US DOD choice and again, felt like it was overkill.

My normal method of choice is a 1 pass PRNG twice a week, sometimes I then defrag the computer and immediately (without restarting the computer) I run another 1 pass. Once a month I do a 4 pass PRNG run, then defrag then run another pass (usually just a 1 pass PRNG, but if I don't need to access the computer in a hurry, I do another 4 pass PRNG).

 

[jberaser]

My normal method of choice is a 1 pass PRNG twice a week, sometimes I then defrag the computer and immediately (without restarting the computer) I run another 1 pass. Once a month I do a 4 pass PRNG run, then defrag then run another pass (usually just a 1 pass PRNG, but if I don't need to access the computer in a hurry, I do another 4 pass PRNG).

Thanks for the info. I normally use Gutman simply because I may only be running it on one or two folders so even an hour or two doesn't matter. But I agree that 40 hours or more could be tough on a hard drive and wouldn't want to do that. I've never done the free space erase but figured it wouldn't hurt to do it, and I'll start slow - likely 1 pass just to time it. Thanks again.

Regards,

JB

 

[Overwriter]

In my view, a 35 pass run is overkill.

I agree completely and I was pleased to see the default setting for Eraser 5.8.4 changed from this to the 1 pass PRNG.

Has anyone ever read or heard of a case where data has actually been proved to be recovered from a modern hard drive after a single pass with Eraser PRNG ?

I can imagine a case for multiple overwrites on something like a floppy disk or something similar as I am sure the heads are not as accurate as on a modern hard drive but anything else I would be completely happy with a single pass overwrite.

 

[jberaser]

In my view, a 35 pass run is overkill.

I agree completely and I was pleased to see the default setting for Eraser 5.8.4 changed from this to the 1 pass PRNG.

Has anyone ever read or heard of a case where data has actually been proved to be recovered from a modern hard drive after a single pass with Eraser PRNG ?

I can imagine a case for multiple overwrites on something like a floppy disk or something similar as I am sure the heads are not as accurate as on a modern hard drive but anything else I would be completely happy with a single pass overwrite.

I started using eraser some years ago and, reading some of the materials about it and erasing on the net I just assumed that if there was a one pass option and then this 35 pass, there must be quite a difference in the effectiveness of one over the other, so went with what appeared to be the best option. Some materials I read seemed to indicate that also, but it was some time ago and I don't recall where I found it, although it might have been through the Eraser site.

Regards,

JB

 

[Overwriter]

Hi jberaser

I started using eraser some years ago and, reading some of the materials about it and erasing on the net I just assumed that if there was a one pass option and then this 35 pass, there must be quite a difference in the effectiveness of one over the other, so went with what appeared to be the best option. Some materials I read seemed to indicate that also, but it was some time ago and I don't recall where I found it, although it might have been through the Eraser site.

I understand, however I really do believe that you could save your hardware an awful lot of wear and tear by simply sticking to the single random pass, also saving you a lot of time !

If there is ever anything on your hard drive that you believe warrants a 35 pass then you might want to consider physically destroying that drive as they are so cheap now. Possibly the best solution for you might be whole disk encryption, thereby ensuring that no data hits the drive unencrypted.

I am just concerned about people using the 35 pass on a regular basis and I worry about the unnecessary wear to their drives.

Anyway, only you know how high your threat level is considering the sensitiveness of your data, in which case it may be necessary for you to use the 35 pass.

Keep those disks clean ! :lol:

 

[jberaser]

Hi jberaser

I understand, however I really do believe that you could save your hardware an awful lot of wear and tear by simply sticking to the single random pass, also saving you a lot of time !

If there is ever anything on your hard drive that you believe warrants a 35 pass then you might want to consider physically destroying that drive as they are so cheap now. Possibly the best solution for you might be whole disk encryption, thereby ensuring that no data hits the drive unencrypted.

I am just concerned about people using the 35 pass on a regular basis and I worry about the unnecessary wear to their drives.

Anyway, only you know how high your threat level is considering the sensitiveness of your data, in which case it may be necessary for you to use the 35 pass.

Keep those disks clean ! :lol:

Actually there's nothing that requires a 35 pass on my HD, as I doubt that even my financial stuff would be of much value to a hacker if my computer got into the wrong hands, although it would be bad if that happened I had never put my mind to the extra work on the HD (I only use Eraser every few months) until I thought it might be nice to try out the unused disc space feature which I've never done. Given that I tend to erase complete folders of stuff anyway, I likely don't even need to erase the unused space, let alone consider trying it with a multiple pass. Appreciate your info, though.

Regards,

JB

 

[Overwriter]

Hi JB

Have you ever considered Truecrypt ? Its free and open source.

Available here.
http://www.truecrypt.org/downloads.php

You could buy one of those flash drives and encrypt the entire drive, somewhere very safe for you to store your financial stuff etc. If you run everything from the flash drive there will be very little saved to your hard disk for you to have to erase. However a free space wipe is a good thing to do now and then, safety first !


If you are worried about your page file then this is great !

http://www.geocities.com/phosphor2013/csg2kntxp.zip

It is a small program that encrypts your page file on the fly, it just runs in the background and you don’t realise it’s there ! Its free too ! :wink:

 

[jberaser]

Hi JB

Have you ever considered Truecrypt ? Its free and open source.

Available here.
http://www.truecrypt.org/downloads.php

You could buy one of those flash drives and encrypt the entire drive, somewhere very safe for you to store your financial stuff etc. If you run everything from the flash drive there will be very little saved to your hard disk for you to have to erase. However a free space wipe is a good thing to do now and then, safety first !


If you are worried about your page file then this is great !

http://www.geocities.com/phosphor2013/csg2kntxp.zip

It is a small program that encrypts your page file on the fly, it just runs in the background and you don’t realise it’s there ! Its free too ! :wink:

Thanks for the links - I'll check them out.

The main reason I even bother with eraser is that I generally upgrade my computer every 2 years, and part of the deal is that I trade in my previous one, so in the end I don't know who's going to get my previous one. I do, of course, format the HD before giving up the old computer, but figured there was more safety in also erasing folders that contain sensitive info after I have backed up that info onto DVDs. But I'll definitely check out the stuff at those links.

Regards,

JB

 

[Overwriter]

The main reason I even bother with eraser is that I generally upgrade my computer every 2 years,

Lucky guy !!!! :lol:

and part of the deal is that I trade in my previous one, so in the end I don't know who's going to get my previous one. I do, of course, format the HD before giving up the old computer,

Cleaning your disk before handing it over is a good idea, but if you really want to make sure your data is destroyed and safe from criminals or snooping hackers then I suggest instead of formatting use DBAN.

DBAN is made for exactly your situation, totally wiping an entire disk before selling it etc.

I am sure you are already aware of DBAN but here is a link anyway.

https://sourceforge.net/project/showfil ... p_id=61951

 

[jberaser]

and part of the deal is that I trade in my previous one, so in the end I don't know who's going to get my previous one. I do, of course, format the HD before giving up the old computer,

Cleaning your disk before handing it over is a good idea, but if you really want to make sure your data is destroyed and safe from criminals or snooping hackers then I suggest instead of formatting use DBAN.

DBAN is made for exactly your situation, totally wiping an entire disk before selling it etc.

I am sure you are already aware of DBAN but here is a link anyway.

https://sourceforge.net/project/showfil ... p_id=61951

No, I hadn't been aware of DBAN, but downloaded it just now. I don't have any floppies so had to try using a CD-R. I'm not very familiar with ISO and other image files of that sort, so following the instructions in the Readme online, I double-clicked the ISO and it opened MagicISO, which I'm also not that familiar with. So I right-clicked the ISO instead and told it to open with Nero. Nero opened and burned it as an image. The CD now has several folders as wel as files, the 1.4mb file being a .ima file. It seems to me that for this thing to be able to boot my system from a cold start it would need an exe or com file of some sort.

Can you give me any more advice? When MagicISO opened it has a button that you can choose that says Bootable, but I suspect that is just to create a regular bootable disc. I haven't had the program long so don't really know it.

And, by the way, I assume that unless I want to nuke my hard drive, when I do get the CD set up properly it would be fatal to reboot my system with that CD in the drive, is that correct?

Regards,

JB

 

[Overwriter]

Hi JB

Before we go any further be careful with DBAN !!!!!

As you suspected DBAN will wipe everything and I mean everything on the selected drive. Eraser erases what you tell it to but DBAN obliterates the disk !

Also do not leave your DBAN CD / Floppy in your computer, ever ! There is always a chance you could accidentally wipe the wrong disk.

I am sorry for being so blunt here but I don’t want to read a post from you saying that you have lost all your data !

Now we have the warnings out of the way lets see if we can make you a DBAN disk.

It sounds like you may have already made a disk using Nero. That might actually work but you asked about magic ISO. Unfortunately I don’t have Magic ISO so I cannot comment on it much, however I think you should have selected bootable when writing it.

Before we go into how to make a DBAN disk with MagicISO I think it would be a good idea to see if the one you wrote with Nero works first that way we can avoid doing the job twice.

Unplug the IDE cable from all the hard drives in your computer and also any usb connected drives etc.

Go into BIOS and select the option to boot from CD.

Put your DBAN CD into the CD drive. (Make sure you clearly mark the CD as being DBAN)

Double check that all hard drives have been disconnected and also any usb connected drives etc.

Start your computer and see if DBAN boots.

Obviously you won’t get very far with it as you don’t have any connected drives but you will at least know if you have made a DBAN disk.

Let me know how you get on and if you don’t think you have made the CD properly I will try to help you.

Don’t forget to remove the CD before connecting your disks and rebooting !!!

 

[jberaser]

Hi JB

Before we go any further be careful with DBAN !!!!!

As you suspected DBAN will wipe everything and I mean everything on the selected drive. Eraser erases what you tell it to but DBAN obliterates the disk !

All of your info is appreciated, but I'm not going to bother going through all of the stuff you suggested just to see if I have a good DBAN burn - just not worth the effort for my purposes. If I find a floppy I'll try the floppy version, but otherwise I'll just live without it.

But thanks again for the other software you also pointed me to, and for your time and effort.

Regards,

JB

 

[FreeK]

Hi there,

Is there a DBAN for some partitions of the HDD only ? :shock:

My Hard disk is about to be inspected by a Pro company like OnTracks and I wouldn't like them to open my private files which are on a separated partition than the "professional" stuff. 8)
However I noted that in spite running Eraser's 35 x overwriting, you can still see and sometime even recover the files !! :evil:

 

[Overwriter]

Hi JB

But thanks again for the other software you also pointed me to, and for your time and effort.

You’re welcome.

 

[Overwriter]

Hi FreeK

However I noted that in spite running Eraser's 35 x overwriting, you can still see and sometime even recover the files !!

Are you really sure about that ?

Did you empty your recycle bin before erasing ?

Did some of the files look like DLL’s ?

Could you actually open any of the files you thought you had recovered ?

Were any of the filenames actual filenames you recognised ?

Did you perform a full free space wipe or did you just delete individual files ?

By the way 35 pass is overkill, if you have data that you believe warrants that sort of deletion you should physically destroy the hard drive.

 

[Robbie]

and part of the deal is that I trade in my previous one, so in the end I don't know who's going to get my previous one. I do, of course, format the HD before giving up the old computer,

Cleaning your disk before handing it over is a good idea, but if you really want to make sure your data is destroyed and safe from criminals or snooping hackers then I suggest instead of formatting use DBAN.

DBAN is made for exactly your situation, totally wiping an entire disk before selling it etc.

I am sure you are already aware of DBAN but here is a link anyway.

https://sourceforge.net/project/showfil ... p_id=61951

No, I hadn't been aware of DBAN, but downloaded it just now. I don't have any floppies so had to try using a CD-R. I'm not very familiar with ISO and other image files of that sort, so following the instructions in the Readme online, I double-clicked the ISO and it opened MagicISO, which I'm also not that familiar with. So I right-clicked the ISO instead and told it to open with Nero. Nero opened and burned it as an image. The CD now has several folders as wel as files, the 1.4mb file being a .ima file. It seems to me that for this thing to be able to boot my system from a cold start it would need an exe or com file of some sort.

Can you give me any more advice? When MagicISO opened it has a button that you can choose that says Bootable, but I suspect that is just to create a regular bootable disc. I haven't had the program long so don't really know it.

And, by the way, I assume that unless I want to nuke my hard drive, when I do get the CD set up properly it would be fatal to reboot my system with that CD in the drive, is that correct?

Regards,

JB

did you download the .iso file for DBAN version 1.0.7? This is the current stable release (there is also a beta, upgraded, version with a much longer version name). I have version 1.0.7, it contains a .IMA file (of 1,400kb in size), which is a WinImage file. Additionally it has 4 folders (with files) as well as 3 text files and a file titled BOOT_CATALOG. These are all the files you need to run DBAN, you don't need to make the disk bootable via your burning software (eg Nero), nor does it need an exe file on the disk as the image on the disk has its own self extracting exe file, which is contained in the .IMA file.

You can test that the disk is bootable without actually going as far as running DBAn, and without having to detach the hard drive. Though I will say this - do it at your own risk! The default for DBAN is that you have to physically start the destruction (of all data on the hard drive) by choosing an option, so if you're feeling brave...

1. Ensure that the startup option in the BIOS is set to the CD / DVD drive.

2. Insert DBAN disk (and as suggested, mark the disk that it is DBAN - I have marked "Warning - DBAN" on my disk, though there something on the DBAN CD you can print off (in the MEDIA_STICKERS folder) and attach to the CD if you want.

3. At startup the disk will run - and the DBAN program should run, directly into RAM, unloading all necessary items for it to run (it is Linux based)

4. The first screen in this tutorial will then appear:

http://www.security.ku.edu/download/DBAN_Tutorial.pdf

The tutorial is for version 1.0.4 but much is still the same in v.1.0.7.

If you see the fisrt screen in that tutorial then DBAN has loaded successfully on your computer, in RAM.

If you are curious to proceed further then do not use the autonuke option - the DBAN program will start to wipe your hard drive with no further prompts (3 pass wipe is the default setting in that option). Pressing F2 and / or F3 will just give you lots of information about DBAN, pressing the Enter key will take you into DBAN in interactive mode (where you choose the method of wiping, the amount of passes - up to 99! - etc. If you do get curious and enter the interactive mode DO NOT(!) press the F10 key as this will start the wipe process based on the settings you choose. Better to...

5. Remove the CD and switch off your computer, then enter the BIOS rechange startup settings etc.

6. As the DBAN program is running in RAM when you switch off your computer the program is wiped and can only be loaded once more by running the DBAN disk.

 

[Robbie]

Hi there,

Is there a DBAN for some partitions of the HDD only ? :shock:

My Hard disk is about to be inspected by a Pro company like OnTracks and I wouldn't like them to open my private files which are on a separated partition than the "professional" stuff. 8)
However I noted that in spite running Eraser's 35 x overwriting, you can still see and sometime even recover the files !! :evil:

DBAN version 1.0.7 will show all the partitions on a hrad drive. However, it doesn't label the partitions in such a way that you can tell which partition is which - meaning you are using pot luck to guess which partition is the one you want to delete.

When I run DBAN in interactive mode I get three options to delete: the whole hard disk drive, Partition 1 and Partition 2. I've used the program enough to know that Partition 1 is my Recovery solution to reinstall the factory image, and partition 2 is the C: drive which contains the operating system etc. However you will not know which partition on DBAN relates to which partition on your computer and trying to second-guess could be a costly exercise if you get it wrong.

 

[Overwriter]

Hi Robbie.

As far as I was aware DBAN version 1.0.7 doesn’t wipe the HPA. (Host Protected Area). I have never tested this as I install my OS from CD’s and Ghost images and so I have never had a HPA.

Have you experienced DBAN failing to protect the HPA ?

Thanks.

 

[jberaser]

did you download the .iso file for DBAN version 1.0.7? This is the current stable release (there is also a beta, upgraded, version with a much longer version name). I have version 1.0.7, it contains a .IMA file (of 1,400kb in size), which is a WinImage file. Additionally it has 4 folders (with files) as well as 3 text files and a file titled BOOT_CATALOG. These are all the files you need to run DBAN, you don't need to make the disk bootable via your burning software (eg Nero), nor does it need an exe file on the disk as the image on the disk has its own self extracting exe file, which is contained in the .IMA file.

I have the same files and folders as you on my DVD, plust 2 shortcuts - winimage and Darik_5_Boot_and_nuke, so I imagine it burned as expected.

I have also taken your very good info and saved it as a text file to follow when the time comes to trade in my computer.

I have one question. When the time comes to nuke the HD, how do I change the BIOS to make sure the system boots from the DBAN DVD? I imagine I would first change this, then turn off the system, then put the DBAN DVD into the DVD drive and reboot. But I have never changed any bios settings so don't quite know how to do this.

Thanks for all your good info. If would be nice if it was in the DBAN Readme.txt file!

Regards,

JB