chkdsk fragments

bern · Joined: Mar 12, 2007 Posts: 1487 Location: ann arbor

I recently had a disk failure, and used chkdsk /f. It recovered usable fragments of files, and a bunch of unidentified file fragments it labeled "file000.chk", "file001.chk", etc. Is there a program around that will glue these nonspecific fragments onto the usable fragments so that an approximation of a complete file can be recreated?

This question is intended as a general question. But for information, the fragmented files are .jpg images.

thanks

goretsky · Posted: Sun Dec 21, 2008 11:45 pm Post subject:

Hello,

You can try making copies of the files, renaming them from a .CHK to a .JPG extension, and then running a JPEG repair program against them. An earlier message thread here discusses several programs you can try.

Regards,

Aryeh Goretsky

bern · Joined: Mar 12, 2007 Posts: 1487 Location: ann arbor

Baby_Tux · Joined: Mar 06, 2007 Posts: 1242

I did a GOOGLE on "what is a .chk file" & came up with this info. (you may want to do the same as there is a LOT of info here that you may want or need to know before starting)

(Short of the link below) --- You pretty much need a HEX EDITOR to view these files to see if they are of any use. They are for "repairing" but most don't know how to use them & just delete them.

Another line I found (& my personal thinking) "CHK files typically can be deleted since the information has been moved somewhere else on the disk" - (personally, I think, in most cases, it is just dupe info, anyway. But from what I just read, not always)

Here is info on it along with some programs to actually USE that date.
Personally, I don't know about these as I just found them so use at your own discretion. & run a virus scan on them.

http://www.ericphelps.com/uncheck/

If you DO try them, please post your results.

BTW: I have yet to try to salvage anything from any CHK file. Even though I HAVE looked at them with a HEX EDITOR (all I had) & I found that there wasn't enough info to go on to do anything with them. MAYBE those files in the link will do the trick if you REALLY need to do a salvage on them.

goretsky

Hello,

Have you considered contacting the authors of any of the picture repair programs asking if they have additional utilities which may attempt to "stitch together" the 32KB files into recognizable pictures? One (or more) of them might have an experimental utility or program not quite ready-for-release you could try.

Regards,

Aryeh Goretsky

bern · Joined: Mar 12, 2007 Posts: 1487 Location: ann arbor

zlim · Joined: Mar 11, 2005 Posts: 2747

Did you format the camera card in the computer? It's my understanding that the best way to format a camera card is through the software on the camera and NOT through the computer.

I also never load the camera software on any computer. I put my camera cards into a card reader which sees the card as an external hard drive. I then drag copies of the pictures to a folder on my computer and burn them to a CD for archiving. After I'm sure I have the pictures burned to a CD and can open them, then I take the pictures that I copied to the computer and start any editing I want to do.

bern · Joined: Mar 12, 2007 Posts: 1487 Location: ann arbor

Baby_Tux · Joined: Mar 06, 2007 Posts: 1242

Well this is interesting. I thought we were talking about a HD, NOT a memory card.
This is a whole different ballgame & needs to be treated quite differently. From what I've gathered over the years, the tools that you use on a HD are DIFFERENT than the ones you use on a memory card. So what I posted just went out the window. SORRY!

But glad your making some headway. BTW: I'd be looking at the card as being bad. In my camera I tried a 1G (cheap) card & had nothing but trouble. Intermittent at best. Unreliable at the worst times. So I took it back & got a better quality 512, works great. & I have plenty of room even at the full res of the camera. (4Mp)

So first thing I'd do is try a good quality card, you can always take it back if that isn't it & you don't need it.
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ALSO - not 100% sure but I DON'T THINK you are supposed to run chkdsk on a memory card. I believe it will screw them up. (I need to check on this) DO know that there are "card fixers".

UPDATE: I did some checking & it appears to actually be OK to run this on a memory card. Funny, I could have SWORN I read / heard / was told, not to. I guess I was dreaming again. Oh, well!!!

drwho07 · Joined: Nov 29, 2007 Posts: 2240 Location: Central FL, USA

Going all the way back to DOS days, there have been .chk files.
DOS was pretty good, but not perfect and sometimes when you'd delete a file that was fragmented, all of the pieces were not put back into the list of available sectors. Those unattached clusters would continue to build up on the hard drive till someone would run Chkdsk (Check Disk). It would then find those unattached fragments and put them into actual files with the .chk extension.
It was always S.O.P. to just delete all those files to free up the space on the hard drive.

Since DOS, even the one in XP, continues to create unattached clusters, it's always a good idea to run "Chkdsk /r" every once in a while to clean up and verify the hard drives integrity.

Follow chkdsk with Disk Cleanup and Defrag for a better running hard drive.
* Even Disk Cleanup will delete "Old Chkdsk Files".

Happy Holidays!
Doc Cool

bern · Joined: Mar 12, 2007 Posts: 1487 Location: ann arbor

bern · Joined: Mar 12, 2007 Posts: 1487 Location: ann arbor

Baby_Tux · Joined: Mar 06, 2007 Posts: 1242

["bern"]
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OK - now I see... Makes a difference, doesn't it.
I take it from this... "But I had a trashed card, so it didn't matter" you have your problem resolved. - Great!

goretsky

Hello,

One thing I have noticed with an Olympus camera using xD-Picture memory cards is that simply removing the card from the turned-off camera, placing it in a generic card reader to copy the files to a PC and re-inserting the card when done caused the camera to report an error with the memory card. From what I have read, xD-memory cards do not have an embedded controller built in like SD-types of memory cards, which means the camera or card reader they are plugged into has to provide these functions. I suspect that when I was using the card reader the operating system wrote something back to the card which the camera did not like. I was able to use the PhotoRescue program to recover photos and repair cards when this occurred, but would suggest using the camera's USB cable to download pictures in the future.

I have not had this type of problem with cameras from Canon or Nikon using SD/SDHC memory cards and a variety of card readers, and prefer this method since it means no specialized software from the camera vendor has to be installed on the computer.

Regards,

Aryeh Goretsky

goretsky

Hello,

I think it is the algorithms for data recovery which are different. Fundamentally, a device is going to get accessed using the same set of disk I/O commands regardless of its type, so it is probaby more a matter of figuring out the order of adjacency for sector ("memory cells") and accessing them in the correct order to look for data. There may be a little bit more invovled because of how wear-leveling algorithms, place data on the flash, but then again, that may be something which is handled by the card and the data recovery program doesn't have to compensate for.

Regards,

Aryeh Goretsky

goretsky

Hello,

If the entry for a file in the directory entry table (DET) was marked as deleted (first character in filename set to "⌂" (ASCII 127, a/k/a DEL character) then it wouldn't matter what clusters were subsequently used, since starting cluster for the file in the DET and linked list in the file allocation table (FAT) were no longer reserved and freed up for use.

Cross-linking occurs when the address (location) of a cluster for a single file appears in the FAT for two (or more) files.

Regards,

Aryeh Goretsky