March 29th, 2018, 14:37
March 29th, 2018, 20:43
March 29th, 2018, 23:46
You just need to corrupt a few bytes to make the archive unusable, so that 200kb could, in theory, be enough to corrupt a lot of files.
Also, even if you are using some strange recovery software, you should wait for them to complete their scannint. Stopping it in the middle won´t bring good results, because the software may wait for doing some organization of its lists after the end of the scanning.
1) How bad is downloading small files prior to recovering? I understand overwriting makes most retail software struggle, but surely 200kb and a few Mbs of temporary browsing data can't overwrite 10+GB of pics?
3) Why was it possible to recover so many old pictures and not a single one had a problem opening except the pics that I intended to restore?
2) I assume the first recovery software may have done some damage, but I had stopped the scan when it had only found about 20-30% of all the pics deleted and only attempted to recover some of those. Therefore even if it corrupted those files, the other pics found later should have been fine if that was the issue?
4) Is there any way to still attempt to recover these photos without professional help? Just for completeness of the test.
5) If this was a real data recovery, what software / method / steps would you have taken to increase chance of restoring the data?
March 29th, 2018, 23:47
You just need to corrupt a few bytes to make the archive unusable, so that 200kb could, in theory, be enough to corrupt a lot of files.
Also, even if you are using some strange recovery software, you should wait for them to complete their scannint. Stopping it in the middle won´t bring good results, because the software may wait for doing some organization of its lists after the end of the scanning.
1) How bad is downloading small files prior to recovering? I understand overwriting makes most retail software struggle, but surely 200kb and a few Mbs of temporary browsing data can't overwrite 10+GB of pics?
3) Why was it possible to recover so many old pictures and not a single one had a problem opening except the pics that I intended to restore?
2) I assume the first recovery software may have done some damage, but I had stopped the scan when it had only found about 20-30% of all the pics deleted and only attempted to recover some of those. Therefore even if it corrupted those files, the other pics found later should have been fine if that was the issue?
4) Is there any way to still attempt to recover these photos without professional help? Just for completeness of the test.
5) If this was a real data recovery, what software / method / steps would you have taken to increase chance of restoring the data?
March 30th, 2018, 7:06
rogfanther wrote:1 - Its bad. You just need to corrupt a few bytes to make the archive unusable, so that 200kb could, in theory, be enough to corrupt a lot of files.
As it was a SSD, possibly it has TRIM enabled , or win10 ran it, so that would explain your results.
Also, even if you are using some strange recovery software, you should wait for them to complete their scannint. Stopping it in the middle won´t bring good results, because the software may wait for doing some organization of its lists after the end of the scanning.
abolibibelot wrote:You just need to corrupt a few bytes to make the archive unusable, so that 200kb could, in theory, be enough to corrupt a lot of files.
In this case, if I understand it correctly, “dada55” attempted to recover folders containing individual files, not compressed archives.
With Recuva in “quick scan” mode (and other softwares which have that option like GetDataBack) it only takes a few seconds, a minute at most, to scan the whole filesystem. In a case like this, where files were recently deleted, if the files are still recoverable, meaning, if they were not yet overwritten, the quick scan is enough in most situations. (Although I've discovered recently that large files could be unrecoverable that way.)
A software which I use sometimes when I just need to recover a file I just deleted on Windows is HandyRecovery (the 1.0 version which was completely free) : it lets you browse the file tree while it is still building it, you can stop it as soon as it displays the wanted file, it will be able to recover it completely (unless it's been overwritten but then nothing will), and for a large partition with many many files on it and a huge MFT it can be way quicker than to wait for Recuva to complete its quick scan. Also the .exe can be run with no install, even from an external device.
Could be explained by Murphy's Law, or indeed if it's a SSD the Trim command is designed to overwrite the deleted files as a background process.
As to why you still can find old pictures, I couldn't say. Are you sure that they were actually deleted, that they weren't stored somewhere as (still allocated) temporary files ?
Any half decent recovery software should not write anything to the scanned drive – neither during the scan, nor after the completion when choosing the location where the files should be extracted, it shouldn't even let you attempt to write on it if you want to. But some of them are less than half decent...
Recently I tried to remotely help someone who had accidentally deleted an important Powerpoint file he was working on, which was stored only on a USB pen drive, 16GB capacity, about 8GB of free space which should be plenty ; he had tried a bunch of recovery softwares, to no avail. I made a quick scan with Recuva, which indicates if the deleted files have been overwritten and if so, by which file (it's not 100% reliable in my experience but most of the time it does provide accurate information) : the wanted file had been overwritten precisely by files extracted with one of those recovery softwares (which did not prevent him to do so), or, ironically, by files from a “FileHistory” directory, which is apparently related to an automatic recovery function in Windows 8+ (I'm still using Windows 7 so I didn't know about it). You'd think that it should have been unlikely, considering the large amount of free space, but it did happen. And even Recuva (which is otherwise an efficient tool) doesn't display a warning when the user attempts to recover a file on the same device and partition.
Again, Recuva should tell you by which files the files you want have been overwritten, if any. It can also display the header of each file, which is the begining of the file in hexadecimal : with some experience, you instantly recognize if a JPEG file has a valid JPEG header or not. If there's garbage instead, or just zeroes, then nothing can be done, even by a professional, the original file is gone.
Alternatively, you can open some of the files in an hexadecimal editor, like WinHex (commercial) or HxD (free), and see what they look like inside. If the file is supposed to be a JPEG picture, first open a few valid JPEG files, you'll see that they always begin with the characters “ÿØÿ”, or “FF D8 FF” in hexadecimal. If a recovered JPEG file starts with anything else, then nothing can “fix” it. If the header is correct but the second half has been overwritten, you typically can see half of the picture, the rest appears as random strips of colors – and again, nothing can fix this.
Doing what you're doing right now is definitely a very good idea : test various methods when you don't need them, so that you know what to do and don't panic when you actually need to recover something and failure is not an option !
Otherwise, you should sort out the good softwares from the crappy ones, know their strenghts and weaknesses, which type of situation best fits each of them, and have them installed on your computer from then on, preventively. You can also run some of them in “portable” mode, if you need to scan your system partition, but if you absolutely need a file which was deleted on your system partition, the best course of action is to shut down the computer immediately, and then scan the drive as an external device from another computer (or better yet, perform a complete image of the relevant partition and scan this instead of the drive itself), because each second you run the drive, data could be written at the exact spot where that file is / used to be.
For instance, Recuva is usually less efficient than R-Studio to rebuild a file tree (which is an advanced commercial software, as opposed to a freeware), but it completes its quick scan in a matter of seconds, whereas R-Studio can take hours, so if you just want to recover one file which has just been deleted it might be overkill, and even counterproductive if the drive is a SSD with Trim enabled : each second the wanted data could be wiped, so the quicker the scan the better. Photorec is designed to recover files in “raw file carving” mode, meaning, it does not rely at all on the filesystem and the metadata, it just extracts files based on their “signature”, which is their header / footer patterns, specific to each file type (one caveat, beyond the fact that you lose the original name as well as the timestamps, is that it's unlikely to fully recover fragmented files). If the files you want have been found by a recovery software with their actual names and sizes and timestamps, it means that the MFT records containing the metadata for those files and their exact locations are still there, but if they have been overwritten then Photorec will not be able to detect them because they no longer have any characteristic header, they now appear as random data (or empty data).
March 31st, 2018, 5:35
I'm pretty sure I saw only zeros in one of the software that allowed me to see the hex data and since TRIM is enabled, I'm gonna say I have no chance of recovering. Funny thing is that I think Recuva was the one software out of the ones I tried with that capability which said the files were not overwritten. However still not open-able when recovered.
Anything I can do to check whether they are actually deleted files?
The reason I even attempted this was I read a post by someone that apparently worked as a data recovery specialist who claimed that some files could be recovered even with multiple wipes and what not by using some statistical tools or something. I felt a bit silly that I couldn't even recover files in a 'controlled test' haha. Though I think he was talking about mechanical hard drives, not sure if TRIM on SSDs may affect his answer.
I also read a bit about TRIM and why its good in regards to performance of SSDs but it does mean that essentially you have no margin for error when deleting files...
Apart from people that do want things to be unrecoverable, surely a better version of the TRIM function would be to setting a delay, i.e. The function starts after say 24 hours in the background.
Knowing what I do now, I would probably take out the storage device straight to professional help if it had really important files.
March 31st, 2018, 9:22
abolibibelot wrote:Trim function, from what I understand, operates at a lower level than the NTFS filesystem, it must be triggered by the SSD's firmware and most likely leaves no trace of which sectors were wiped within the filesystem, so Recuva can't be aware that those sectors were wiped, since they have not been overwritten by another file, they haven't been re-allocated. It will probably not be aware either if you manually wipe a file with an hexadecimal editor (with WinHex for instance : right-click then “Wipe securely”).
If you don't know their exact location, and the software didn't make it explicit if they were deleted or not, I can't see how, now. But for instance, if you extract files with Photorec, you can choose to scan the “free space” only, and each extracted file is named after the number of its first sector (i.e. “f123456.jpg” > first sector of that file is nr. 123456), so even if files were extracted from the whole space, with WinHex you can open the volume, and go to that sector (Navigation > Go to sector) (if files were extracted from the whole device the sector number is “absolute” has to be corrected with the partition offset to obtain the sector number relative to a given partition), it will indicate if that sector belongs to an allocated file or is considered as “free space”.
In R-Studio, files found by signature search are located in a separate folder called “Extra found files” ; but in that folder there are files which have only be found as “raw” files (usually with a random number, or named after their characteristics, like their dimensions for picture files), and files which have also been identified as part of the regular folders, which appear with their native names and timestamps, with a blue arrow symbol, meaning that they are “hard-linked”, they are actually the same file appearing in both locations, if you right-click on such a file and left-click on “Links”, it displays the other location, and clicking on the name of the file directly leads to the other location. There's also a red cross symbol for files/folders which are recognized as having been deleted (they are no longer allocated but still have their metadata intact in the MFT).
It was a post from a Quora question so not a good reference but the guy sounded pretty convincing:From what I know, that pretty much a urban legend (after a single wipe nothing can be recovered, at least with software means, and even with the most advanced technology available I doubt that it's actually feasable to recreate usable files out of those hypothetical faint magnetic traces), but I'd be curious to read that post.
That's indeed a caveat with SSDs... It's a problem for forensics investigators as well.
I don't know exactly how it operates, but it may not be possible if it's indeed at a lower level than the operating system. The operating system could be aware of how much time went by since a given file was deleted, but the firmware most likely can't access that kind of data, it just knows which sectors are allocated and which are not. It would probably make the firmware much more complex to have it deal with that sort of things, which are beyond the scope of strict hardware operation. Data recovery is definitely an afterthought for the designers of storage devices !
Well, it's tricky, because bona fide data recovery experts might be overkill for a simple case of an accidentally deleted folder, and the price tag might be steep for 10GB worth of pictures as in your experiment, while general purpose computer repair technicians, while way cheaper, can be just as likely as the average user to screw things up. (Quick example : a few years ago, I had copied a selection of pictures and videos on my mother's computer. One day, she had a nasty virus, had to call a technician. The dude removed the virus, then he saw that the system partition was almost full – probably because of large restore points or something similar, which would have been easy to pinpoint with something like WinDirStat, and to clean in a matter of seconds. The 1TB HDD had two 500GB partitions, the other was almost empty, so at least he could have moved that large folder with the pics and vids to that partition with no fuss and no loss – using the native Robocopy command line tool even the timestamps are preserved ; but he asked her if he could delete it altogether... She didn't even know it was there for her, she was barely a beginner with the computer, she said there was nothing important in there... and he did delete it that damn dimwit ! O_o And he got paid about 80€ if I remember correctly... I didn't lose anything, but I had spent quite some time to make that selection so I was still quite pissed.)
March 31st, 2018, 13:19
Then I deleted them ("perma deleted" as they were too large to go on recycle bin).
March 31st, 2018, 16:09
April 2nd, 2018, 18:18
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