Re: [OM] Images on SD card held hostage

Subject: Re: [OM] Images on SD card held hostage
From: Moose <olymoose@xxxxxxxxx>
Date: Mon, 22 Jun 2020 12:50:19 -0700
On 6/21/2020 3:26 PM, Mike Gordon via olympus wrote:
Took EM1 MkIII for the NABA flutterby count yesterday.  Beastly hot and stayed 
well away from others and had mask on sometimes. Generally just stayed 10-20 ft 
away as too hot. for mask.

Had used the card in the Mk11 and took a few test shots and decided not to 
format--error.  I did not reformat with GM5 for GX 85 and no issues though I 
did a mock transfer given much more at risk.  As the Oly cams are so close and 
like to use the cards as dig film, thought I'd get away with it.  I had maybe a 
couple decent shots of a Bronze copper but the light was harsh and they did not 
cooperate as too warm.  Windoze does not see the images but the cam does.  Will 
a recovery tool  find them?

Should do. Windows doesn't look at the files themselves, nor do apps like PIE, that access using Windows. It uses the File Allocation Table, a linked list of clusters. Do I recall that there are two of them, one a back-up?

In any case, I suspect that the FAT is broken. In a case where no files have been deleted since formatting, the files are all contiguous in order. In that case, recovery software has a good chance of rebuilding the FAT and recovering all the files. It can run through the disk, looking for standard file beginnings.

When files have been deleted, then others added, it's get trickier, perhaps much trickier. If the camera writes all files at identical size, there's a decent chance. Where compression is used, all bets are off. If a file not on the end is deleted, then a new one written that is even a byte longer, most of the file goes in the empty space, but the last part goes at the end.

Chuck, who managed IBM's PCDOS development, advised never to delete any file on a card. My more relaxed protocol has been to only ever delete the last shot taken. I've never lost an image file.

I have an additional backup already so will reformat and test the card but 
suspect the lack of formatting in new cam was the issue.

This seems unlikely to me. FATs are universal, not camera specific. I think everyone learned from the Oly Fuji xD card debacles with special formatting for panoramas, or some such.

Looking at an SD card in a Sony, there are various bits of stuff in directories that are Sony specific (same as other brands). But, as in every other camera I've used, the actual image files are in subdirectories under the DCIM directory, available as mass storage independent of any other stuff on the card.

I don't remember the exact details. Years ago, I put a card from one brand in a different brand camera, forgetting to format. The new camera just ignored what was on there before and did its own thing, without a glitch.

I suspect a failure in writing, or in the card itself, either memory or memory management. Flash memory cards have their own management firmware, underneath the FAT, and invisible from outside, that varies from the HD protocol that writes out from the hub. They scatter data about to wear level the memory. If that goes bad, all bets may be off.

  Someone will know how to get them off.

I hope so, and that you find it!

File Allocation Moose

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