Modern flash drives force new data to locations that have not been used (as much) as current locations to keep wear as even as possible. I suspect that these newer flash drives divert the shredder to locations that don't include the data you're trying to shred. The data from the file you're trying to shred stays intact while some innocent area gets "shredded". ;-)
That's true, but it should never be visible in any useful way to a file recover program - or to any program for that matter. "Wear levelling" as it's called is all hidden within the hardware.
- Leo 09-Mar-2009
Posted by: Philip at March 8, 2009 8:51 PM
SDelete is a little complicated for the casual user.
I use the freeware Eraser which gives you the option to write once with Pseudorandom Data. After installing the software, you can do a right click on the file name and select ERASE.
i want to view & recover my picture files but how can i recover picture files on my USB if i have already cut them from my USB and paste it on a folder who happens to be inffected by a virus giving it the cause why i cannot view my Picture files anymore.
Posted by: Gamar Damlani at March 13, 2009 9:32 PM
Wear leveling means it is writing the shred to other parts of the memory drive, thus it does not overwrite the original file remnants.
And, voila, the old file remains intact to a file recovery program.
contig is "complicated"??? sheesh.
It would be better to use a truecrypt volume to keep private stuff private on a flash disk. Perhaps the only way.
Wear leveling is implemented at the hardware level and is transparent to applications. If you overwrite byte "x" on the media, then it will always look like byte "x" was overwritten, even though is might reside elsewhere on physical media. Put another way, wear leveling does not increase the chances of file recovery because it's completely hidden.
- Leo 14-Mar-2009
Posted by: t at March 14, 2009 12:03 AM
Wear leveling would increase the chances of recovery if the recovery program is looking at ALL of the free blocks... as there is still a block on that USB that contains that data.
Again, no. Wear leveling does not increase the chances of recovery.
- Leo 15-Mar-2009
Posted by: Nicholas Gimbrone at March 14, 2009 2:33 PM
What about other forms of flash memory? Like SD cards and their ilk. Do they wear out as well?
Yep. Flash memory is much flash memory. There are differences in quality, of course.
- Leo 19-Mar-2009
Posted by: MikeJC in Maine at March 19, 2009 6:08 AM
As someone with a scienctific background it would be easier to recover data from from many passes than from a few and here's why...
Granted the signal of the original files will become weaker the more passes one does, and more difficult to recover, but in essence the file would be less corrupt. The more random passes one does the more the scrambled signal evens out. Everyone should know this from statistics, flip enough heads and tails and you'll get a 50/50 split. It's kind of like cryptography in a way if you visualize each track as a column, but I digress, similarily if you only do a few passes the original signal will be stronger but more corrupt. hd only though not sure about flash.
Um...no. The more you overwrite it with random data the more difficult it will be to recover. (And overwriting ONCE is all you need for flash).
- Leo 23-Mar-2009
Posted by: Chris at March 22, 2009 5:34 PM
Hello,
does "Wear levelling" consider about partititions?
Example: 4 GB USB Stick with two partititions
1. Linux Ext2 - 8MB
2. Windows FAT - Rest of it
If I overwrite partitition 1. once with random data, will there be left data from that partitition somewhere on the stick because of "Wear levelling"?
Wear leveling is not externally visible, period. So while it might be happening under the hood across all bits stored on the device, you would not see it.
- Leo 15-Apr-2009
Posted by: Martin Müller at April 15, 2009 3:28 AM
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Modern flash drives force new data to locations that have not been used (as much) as current locations to keep wear as even as possible. I suspect that these newer flash drives divert the shredder to locations that don't include the data you're trying to shred. The data from the file you're trying to shred stays intact while some innocent area gets "shredded". ;-)
09-Mar-2009
SDelete is a little complicated for the casual user.
I use the freeware Eraser which gives you the option to write once with Pseudorandom Data. After installing the software, you can do a right click on the file name and select ERASE.
http://www.brothersoft.com/eraser-12113.html
Posted by: Mike in Pennsylvania at March 10, 2009 8:59 AMit is very good when delete function not work
Posted by: hemraj at March 10, 2009 12:46 PMWouldn't East-Tec Eraser be the best option for USB and disk?
Posted by: Rocco at March 11, 2009 2:13 AMhttp://www.east-tec.com/
i want to view & recover my picture files but how can i recover picture files on my USB if i have already cut them from my USB and paste it on a folder who happens to be inffected by a virus giving it the cause why i cannot view my Picture files anymore.
Posted by: Gamar Damlani at March 13, 2009 9:32 PMWear leveling means it is writing the shred to other parts of the memory drive, thus it does not overwrite the original file remnants.
And, voila, the old file remains intact to a file recovery program.
contig is "complicated"??? sheesh.
It would be better to use a truecrypt volume to keep private stuff private on a flash disk. Perhaps the only way.
14-Mar-2009
Wear leveling would increase the chances of recovery if the recovery program is looking at ALL of the free blocks... as there is still a block on that USB that contains that data.
15-Mar-2009
What about other forms of flash memory? Like SD cards and their ilk. Do they wear out as well?
19-Mar-2009
As someone with a scienctific background it would be easier to recover data from from many passes than from a few and here's why...
Granted the signal of the original files will become weaker the more passes one does, and more difficult to recover, but in essence the file would be less corrupt. The more random passes one does the more the scrambled signal evens out. Everyone should know this from statistics, flip enough heads and tails and you'll get a 50/50 split. It's kind of like cryptography in a way if you visualize each track as a column, but I digress, similarily if you only do a few passes the original signal will be stronger but more corrupt. hd only though not sure about flash.
23-Mar-2009
Hello,
does "Wear levelling" consider about partititions?
Example: 4 GB USB Stick with two partititions
1. Linux Ext2 - 8MB
2. Windows FAT - Rest of it
If I overwrite partitition 1. once with random data, will there be left data from that partitition somewhere on the stick because of "Wear levelling"?
15-Apr-2009
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