Modifying dates in raw files created by Canon EOS 650D fails randomly

[TheAG]

I am trying to fix some time stamps in photos that were taken with the clock set wrong due to time zone. Due to this problem, they have their date set wrong. The command that I use is exiftool "-DateTimeOriginal+=0:0:1 0:00:0" filename.

There is something strange about applying this command on raw files created by Canon EOS 650D. Sometimes it works and sometimes it won't, and I haven't been able to grasp any logic behind this so far. At times it seems strange enough for me to have considered ideas such as maybe booting the computer and trying again might help. That helped once, but failed another time, so it most likely wasn't really about that the first time either. Also, every now and then, it seems to work on one copy of a file but not on another which resides on different hard-drive. Finally, it often seems that it works fine until certain moment after which any further attempts will fail. I am a programmer myself so all these details seem very weird to me.

The error messages I get is this:
Error: Error writing image data - 2015-11-14/111642-EO2-4632.CR2
    0 image files updated
    1 files weren't updated due to errors

I am running exiftool version 9.46 on Linux Mint 17.

I can try to supply any helpers with more information but as for now, I have no idea what might be helpful.

[TheAG]

I can now confirm something...

I have all those photos on two different hard-drives. One copy is a back-up and the other one is the one that I am trying to work on.

I just copied a file from the back-up to a temp folder on the same hard-drive the working copy resides on. I then run diff on that file (temp copy) and the working copy. They were identical.

I then tried fixing the date for both of them. Fixing the working copy failed as it had before, but fixing the temp copy did work. I could even reverse the fix and apply it again and it still worked.

[Hayo Baan]

Could it be that you simply don't have write permission to the files that fail?

[TheAG]

Could it be that you simply don't have write permission to the files that fail?

No, unfortunately it's not that simple.

[Hayo Baan]

Hmm, weird indeed. I don't really think it is an exiftool issue, but more something with your system.

Do they consistently fail in one location and not the other? Do they have the same file system? Is one disk internal and the other external? ...?

When altering a file, the whole file is written anew by exiftool so there must be enough room to do so (and also the folder it is in must be writable too of course).

[TheAG]

I don't think this is a system issue. I am quite sure that if it were, this wouldn't be the only symptom of it, and yet I haven't noticed anything else.

I haven't analyzed this very profoundly so I can't describe the circumstances in which it happens or doesn't happen.

[TheAG]

Problem solved. It was a system issue, but the root cause of the problem was caused by a feature of exiftool that had an effect I hadn't thought of.

The bunch of photos that I am working on contains ~ 2000 photos and they take 67 GB of hard-drive space. I have shot JPG + RAW, and the raw files probably take 80-90 % of that space. Exiftool creates a back-up copy of each original file, and my hard-drive was close enough to be full so that I eventually run out of space during the process of fixing the dates. The solution was to divide the files into smaller sets and remove the back-ups for each set before processing the next one.

I should have read the manual, but I also wonder if there are other people too facing this same issue every now and then

[StarGeek]

Take a look at the -overwrite_original option.