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#41 2022-03-26 21:25:22

Colonel Panic
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Registered: 2018-11-13
Posts: 547

Re: Essential Apps

I've recently found a utility called Bleach Bit very useful for cleaning up space on my hard drive. I got back over 2GB of space, which has to be worth the trouble;

https://www.bleachbit.org/

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#42 2022-03-26 22:30:21

rbh
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From: Sweden/Vasterbotten/Rusfors
Registered: 2016-08-11
Posts: 1,509

Re: Essential Apps


// Regards rbh

Please read before requesting help: Guide to getting help,
Introduction to the Bunsenlabs Lithium Desktop and other help topics under "Help Resources" on the BunsenLabs menu

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#43 2022-03-30 02:28:07

Colonel Panic
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Registered: 2018-11-13
Posts: 547

Re: Essential Apps

Thanks. There is a snag with using it though - it temporarily fills up a lot of the free space on your partition whilst it's working, though it later clears it again.

Last edited by Colonel Panic (2022-04-09 22:29:03)

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#44 2022-03-30 02:40:09

Bearded_Blunder
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Re: Essential Apps

@Colonel Panic
That'll be the way "Wipe free space" typically works on Linux as opposed to Windows, the usual approach behind the scenes is roughly `dd if=/dev/zero of=/file/where-you-want-space-wiped` then just delete the file when dd reports no more space...

Which you can of course do manually..  Just don't make a typo, easy to wipe the drive instead of the space.


Blessed is he who expecteth nothing, for he shall not be disappointed...
If there's an obscure or silly way to break it, but you don't know what.. Just ask me

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#45 2022-03-30 18:12:53

jeffreyC
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Registered: 2019-09-07
Posts: 115

Re: Essential Apps

Bearded_Blunder wrote:

@Colonel Panic
That'll be the way "Wipe free space" typically works on Linux as opposed to Windows, the usual approach behind the scenes is roughly `dd if=/dev/zero of=/file/where-you-want-space-wiped` then just delete the file when dd reports no more space...

Which you can of course do manually..  Just don't make a typo, easy to wipe the drive instead of the space.

Not a good idea with any SSD or other flash based device, adding extra writes shortens their lifespan.

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#46 2022-03-30 19:51:13

Bearded_Blunder
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Re: Essential Apps

People worry about writes on SSDs too much, if you want to secure erase *free space* there's not many other ways to do it.. and one write or two write cycles? Amounts to pretty much nothing..
If your security model calls for wiping free space, then you accept that like the tyres on your car, they wear down with use, that's not a reason to call a taxi. Or skip going to your destination entirely.

With modern rather than early SSDs you could literally add a daily write zeros to entire drive & restore entire OS to typical use & still expect them to last a half decade or more.

If you've got one of those laptops where the storage is soldered to the motherboard, by all means be prissy about it, otherwise, SSDs are a consumable & easily replaced part.

Last edited by Bearded_Blunder (2022-03-30 21:49:12)


Blessed is he who expecteth nothing, for he shall not be disappointed...
If there's an obscure or silly way to break it, but you don't know what.. Just ask me

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#47 2022-03-31 12:51:21

Colonel Panic
Member
Registered: 2018-11-13
Posts: 547

Re: Essential Apps

Bearded_Blunder wrote:

@Colonel Panic

That'll be the way "Wipe free space" typically works on Linux as opposed to Windows, the usual approach behind the scenes is roughly `dd if=/dev/zero of=/file/where-you-want-space-wiped` then just delete the file when dd reports no more space...

Which you can of course do manually..  Just don't make a typo, easy to wipe the drive instead of the space.

Thanks for replying. When I used to use Puppy Linux that was the way we used to wipe the drive from the live Puppy disk when we needed to (because back then Puppy didn't have any built-in wiping utilities), and it seemed to work OK. I think you also had to give the block size you wanted; 16k or similar.

People who know enough about Linux to know what they're doing (i.e. more than I do) wipe just the beginning and end of the drive, in order to nix any of the structures that get in the way of a new installation without having to go to the time and trouble of a full disk wipe. Here's a thread of explanation;

https://unix.stackexchange.com/question … dev-sda-do

Last edited by Colonel Panic (2022-03-31 12:57:47)

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#48 2022-03-31 13:42:46

jeffreyC
Member
Registered: 2019-09-07
Posts: 115

Re: Essential Apps

Bearded_Blunder wrote:

People worry about writes on SSDs too much, if you want to secure erase *free space* there's not many other ways to do it.. and one write or two write cycles? Amounts to pretty much nothing..
If your security model calls for wiping free space, then you accept that like the tyres on your car, they wear down with use, that's not a reason to call a taxi. Or skip going to your destination entirely.

With modern rather than early SSDs you could literally add a daily write zeros to entire drive & restore entire OS to typical use & still expect them to last a half decade or more.

If you've got one of those laptops where the storage is soldered to the motherboard, by all means be prissy about it, otherwise, SSDs are a consumable & easily replaced part.

More of a concern where people treat them like hard disk drives and think they need to overwrite them 7 times or more. Disk heads were inherently sloppy and data could still be on the edges, an SSD has no slop.

They call it a DOD wipe, but when the DOD want it securely gone they grind the drive to dust, and then securely dispose of the dust.

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#49 2022-03-31 16:12:35

rbh
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From: Sweden/Vasterbotten/Rusfors
Registered: 2016-08-11
Posts: 1,509

Re: Essential Apps

jeffreyC wrote:

They call it a DOD wipe, but when the DOD want it physically demolishsecurely gone they grind the drive to dust, and then securely dispose of the dust.

DOD is short for Department of Defense. The US Military department.
The DOD wipe, was and still is a good standard.

I worked for the Region Vasterbotten IT-department before my retirement.
Computers was replaced by new computers every third/fourth year. When replacing some hundred computers, you can not take out every hard-drive and physically demolish it. (Total amount of computers then was about 10 000. I guess that they has grown since then...)
1.) The labour time is to expensive. 2.) You get better paid for the discarded computers on the second hand market if they are sold with harddive. (ev also with orignal (win)OS).

A DOD wipe is good in most cases when dealing with sensitive data. But, if you are dealing with very, very sensitive data, physically demolishing is prefered. But that affects only a little amount of computers.


// Regards rbh

Please read before requesting help: Guide to getting help,
Introduction to the Bunsenlabs Lithium Desktop and other help topics under "Help Resources" on the BunsenLabs menu

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#50 2022-03-31 19:35:28

Bearded_Blunder
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Re: Essential Apps

Well since the subject has strayed to wiping the entire drive, rather than just rendering deleted files unrecoverable by ordinary utilities, the solution for that with an SSD is to use a self-encrypting one, secure erase then amounts to "change the encryption key" you're then left with cryptographic grade gibberish on the entire drive which it's completely infeasible to decypher/recover. Completely secure, minimal wear. The only time you wouldn't do it that way is if you're subject to regulations that haven't caught up with that method yet.

Some drives have the ATA secure erase command implemented that way, in such cases the secure erase command returns as complete unbelievably quickly.

The commonly used DOD standard is United States  specific (as a standard), other countries often have their own different standards, in situations where a wipe is called for by regulation, it pays to check what wipe algorithm is specified, you could easily do something technically better than required & still be in trouble.


Blessed is he who expecteth nothing, for he shall not be disappointed...
If there's an obscure or silly way to break it, but you don't know what.. Just ask me

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#51 2022-04-01 14:50:01

jeffreyC
Member
Registered: 2019-09-07
Posts: 115

Re: Essential Apps

rbh wrote:
jeffreyC wrote:

They call it a DOD wipe, but when the DOD want it physically demolishsecurely gone they grind the drive to dust, and then securely dispose of the dust.


I worked for the Region Vasterbotten IT-department before my retirement.
Computers was replaced by new computers every third/fourth year. When replacing some hundred computers, you can not take out every hard-drive and physically demolish it. (Total amount of computers then was about 10 000. I guess that they has grown since then...)
1.) The labour time is to expensive. 2.) You get better paid for the discarded computers on the second hand market if they are sold with harddive. (ev also with orignal (win)OS).

In the US it is common for companies to remove the drive, it only takes a few seconds with a screwdriver to remove compared to the time to write multiple passes on each drive.
Having bought several with no drive from eBay sales, yes the selling price is lower, but they still do it.

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#52 2022-04-01 15:01:20

eight.bit.al
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From: Prison
Registered: 2015-10-01
Posts: 1,287

Re: Essential Apps

^ And many then wipe the drive and sell it separately.

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#53 2022-04-01 15:04:22

Bearded_Blunder
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Re: Essential Apps

eight.bit.al wrote:

^ And many then wipe the drive and sell it separately.

More likely they ship them to a company for "secure disposal"& that company then does so.


Blessed is he who expecteth nothing, for he shall not be disappointed...
If there's an obscure or silly way to break it, but you don't know what.. Just ask me

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#54 2022-04-01 20:26:14

rbh
Moderator
From: Sweden/Vasterbotten/Rusfors
Registered: 2016-08-11
Posts: 1,509

Re: Essential Apps

jeffreyC wrote:

In the US it is common for companies to remove the drive, it only takes a few seconds with a screwdriver to remove compared to the time to write multiple passes on each drive.
Having bought several with no drive from eBay sales, yes the selling price is lower, but they still do it.

Attaching power and screen. Power up pc, insert wipe-cd. Set up next pc, and next, and.. and the last (do not remember if we could set up 50 pc). Then go back and detach all and load them in wagon.
It did not take much time.

Remove the hd, attach the hard drive to the vial in the column drill and drill the hd, takes way much longer time. It had to be done if the wipe did not succeed.

So, we also sold some pc without hd...


// Regards rbh

Please read before requesting help: Guide to getting help,
Introduction to the Bunsenlabs Lithium Desktop and other help topics under "Help Resources" on the BunsenLabs menu

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#55 2022-04-01 20:32:28

Bearded_Blunder
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Posts: 978

Re: Essential Apps

rbh wrote:
jeffreyC wrote:

In the US it is common for companies to remove the drive, it only takes a few seconds with a screwdriver to remove compared to the time to write multiple passes on each drive.
Having bought several with no drive from eBay sales, yes the selling price is lower, but they still do it.

Attaching power and screen. Power up pc, insert wipe-cd. Set up next pc, and next, and.. and the last (do not remember if we could set up 50 pc). Then go back and detach all and load them in wagon.
It did not take much time.

Remove the hd, attach the hard drive to the vial in the column drill and drill the hd, takes way much longer time. It had to be done if the wipe did not succeed.

So, we also sold some pc without hd...

Accountants are silly sometimes though.. seem to equate elapsed hours to deal with a machine to labour involved, & the costs are significantly different according to which cost you evaluate.


Blessed is he who expecteth nothing, for he shall not be disappointed...
If there's an obscure or silly way to break it, but you don't know what.. Just ask me

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#56 2022-04-02 16:19:49

Colonel Panic
Member
Registered: 2018-11-13
Posts: 547

Re: Essential Apps

For those who are interested, here is a highly technical paper which deals with the issue of erasing data from SSD drives;

https://www.usenix.org/legacy/events/fa … rs/Wei.pdf

I have a SATA drive, so DBan works fine for me when I need to wipe it. When I had a smaller hard drive I used to use the Canadian RCMP method (8 passes, changing the writeover data slightly each time), but I think that's overkill now that I've got a bigger drive (250 GB) where each pass takes a lot longer.

Last edited by Colonel Panic (2022-04-14 15:32:49)

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#57 2022-04-28 22:44:17

Colonel Panic
Member
Registered: 2018-11-13
Posts: 547

Re: Essential Apps

Colonel Panic wrote:

Thanks. There is a snag with using it though - it temporarily fills up a lot of the free space on your partition whilst it's working, though it later clears it again.

Coming back to this; I ran it today and it filled my hard drive and didn't delete the ginormous file it created in the process of running.

The solution was here;

"Q: I closed BleachBit while it was working for a long time, and now my hard drive is full. How do I fix it?

A: Run BleachBit, and clean the option System - Temporary Files. On Linux, also clean System - Cache. This will delete one or more files that are gigantic and have random filenames.

In case you are using the command line or another application to delete these files, the default location on Linux is ~/.cache/. If it is not the same partition, /tmp/ is also used. On Windows, the default locations are %TMP%. If there are other fixed drives such as D:, they are also used.

If you changed the default options under Preferences - Drives, look there for the large files.

These instructions are valid since BleachBit version 1.2 released in 2014."

https://docs.bleachbit.org/doc/frequent … tions.html

In this instance, the file (which I had to delete from another distro, Sparky, since mc wouldn't run with no space left on the partition) was over 10GB in size, the largest individual file I've yet seen.

Last edited by Colonel Panic (2022-04-29 06:49:34)

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#58 2022-04-28 23:09:17

Bearded_Blunder
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Re: Essential Apps

Erase free space on an SSD

sudo fstrim -a -v

Reference for the effectiveness therof: https://www.dataclinic.co.uk/data-recov … r%20exists.

If a moderate size chain of data recovery specialists can't do it it's "effective enough" for me at least. Now, if you think a three letter agency are going after you you might need more.

Last edited by Bearded_Blunder (2022-04-28 23:16:04)


Blessed is he who expecteth nothing, for he shall not be disappointed...
If there's an obscure or silly way to break it, but you don't know what.. Just ask me

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