How can a 1GB CF card hold 2GB of data???

[Link]

I've recently had 2 of my CF cards formatted. The cards, a Sandisk Ultra II of 512MB and a Kingston of 1GB, were full of D70 NEF + JPEGs. I didn't take any photo or write anything on those cards since then.

I don't know exactly how the formatting was done, but I expect a standard in-camera formatting, nothing really fancy.

I've searched the Web for solutions and found this accepted as conventional wisdom:

When you format a CF card, the data doesn't really get deleted from the card. The only thing that happens is that the computer makes the directory on the card empty and marks all the data blocks on the card as being free to be overwritten with new data. As long as you didn't record any new data on the card, the photos will still be there.

I've tried a few data recovery utilities ("media recover", "zero assumption recovery", "datarescue") and run several deep scans on my cards.

Here is the weird problem:

Those programs actually recovered lot of photos from much before my latest format, but not the latest files written immediately before the format.

At the time it was formatted, my cards were pretty much full with very valuable pictures.

However, those software recovered photos from a shoot about one week before the formatting, including also some photos I took in mid-May 2006!!! Since May I've filled and formatted my card several times...

How come the new files didn't overwrite those older ones? All in all, it looks like my 1GB card was holding 2GB of data (the older files + the new data I lost to the accidental format)

I still wonder about the files I lost a few days ago, the ones I really need to recover and which were supposed to fill up my CF cards capacity!?!

Just sharing this experience here and see if anyone has faced a similar situation. Or any guess as to how a 1GB card can hold 2GB of data?!

[Justin]

It can't

Did you actually get more than 1Gb recovered?

Didn't think so

When you delete something, the first byte from the File Allocation Table (FAT) is removed. When you format, it just deletes the first byte from all the FAT entries. That space allocated to that FAT entry is marked as reusable.

Photos aren't neccessarily stored contiguously (in one block). You can get fragmentation on flash cards.

Have you checked the pictures that have really old names? They are just old FAT entries that were recovered, not the files? The actual pics may be corrupt

[Wocka]

It's possible to recover data from hard drives from up to 7 formats of the disk. I would expect a CF / SD card would be the same as Justin has explained, when your formatting the card it's deleting the "index", not the files them selves.

This is why your able to recover files from months ago, as to why you can't get the images your after, who knows. If it's really that important (eg for business reasons) there are companies out there that can restore formatted data. Last time I sent a laptop off to be recovered it cost close to $1k and took 2 weeks. But we recovered most of the data and what we were after specifically.

Note: Do not chuck out old hard drives in the clean-up etc. There are tools available on the net that write “0” across the whole disk, but I always take my hard drives apart and make sure I leave my fingerprints on the disk platter itself.

I love the ACA stories about going to the computer market, buying HDD’s and restoring the data. Not good if you’ve ever written a fax with your Credit Card No# and expiry date on it.

Cheers,

[Link]

It's true I recover only 1GB of data, but is it wrong to assume that at one given moment my card was actually holding 2GB of data? (I know it sounds impossible)

I mean, I did have 1 GB of valuable photos before the formatting, I could review them on the D70 screen without any problem so they were obviously written on the card.

But at the same time, this gigabyte of useless photos I just recovered from the same CF card must have happily coexisted with my gigabyte of valuable photos, right?

I still don't understand why the newer photos didn't erase all the old ones. I still haven't used my 1GB CF card and wish I could find some data recovery software going 'deeper' than those I mentionned above...

Link.

[Justin]

is it wrong to assume that at one given moment my card was actually holding 2GB of data?

Yes.

Did you look at the photos after you recovered them?

[Yi-P]

This occurs when you have your card filled up by long before, and whats being recovered are bits and fragments of the files long ago. It may only contain the filename itself but currupted in the image part, or vice versa.

A CF card is a big piece of Integrated Circuit (IC) chip made up with thousands of logic gate (NAND gate) trasistors inside.

Imagine a large container box, filled with tiny little numbered balls. Each of them can be writen down with tiny bits of information. And you have a sheet of paper where says how comination of the number can make up a sentence or word.

When you write files into the card, you simply write something on the random numbered balls, and write down on your 'reminder sheet' which numbers combined to make your 'sentence'. As by then, the FAT is allocated along with the tiny bits of binary information which it belongs.

When you format the card, you simply rip and destroy your 'reminder sheet' given you a new one now. Your box of numbered balls is still there with all the little balls untouched. You just forgot where and how they are combined into one. When you record new information into the box, you just overwrite whatever is on top of the tiny balls and write down your new combination on your new reminder sheet for this purpose, as "overwriting".


Upon recovering from this with a software, it will try and reasemble a new reminder sheet for you with a logical order and combining the bits of information to recover the file. You may get something from the bottom of the box which reads 'may 2005' but not necessary be linked back to your image or has other vital information of the image.


Err, Im not sure if I made sense on this one, but this is how I try to explain the logic behind storing digital files and allocation.

[Link]

Update.

I've recovered an entire 1GB of data - no more, no less. Remember that, when my CF card was formatted it was entirely filled up with photos taken on Sept 12.

I recovered about 70 MB of my valuable Sept 12 pictures; only a couple of them corrupted.

The remaining 930 MB were old photos (mostly taken on Setp 5) that I had then deleted. Still, they were apparently not overwritten. None of these photos was corrupted, I can easily open them with Photoshop.

I've emailed the customer service of a media recover software and here is what he replied:

It appears that these older photos were never overwritten due to them being towards the end of the card. I can not tell you exactly why these photos are still on the card and why the photos you want to recover are not showing up

Still a mystery to me...

Link.

[whiz]

It's not uncommon to pick up more than your normal "size" of deleted files. I've recovered 130 gig of files from a 80 gig drive.
Of course, only the totally intact files were usable but the fragmented files's indicated file size added up to a lot more.

[obzelite]

fill the card a few more times and see if you can recover the ones your missing then as they will now have been overwritten a few times

[Link]

fill the card a few more times and see if you can recover the ones your missing then as they will now have been overwritten a few times

That's exactly what I'm going to do! I'll just wait until the stars in the sky are in the exactly the same position as the Sept 13, and then format my card again hoping for a miracle...

Link.