During our trip to London, we got ourselves local SIM cards to avoid ridiculous roaming charges and still be able to use the interwebs. However, the Dropbox auto-upload function decided – for whatever reason – that all the pictures on my phone need to be re-uploaded. I guess it was the fact that I put in another SIM card, because nothing else changed. It only stopped when the battery was almost drained, but by then more than 400 of my 500 MB data allowance were gone -.-‚ Well, at least the network offers a decent upload speed :)
The strange thing is that Dropbox shouldn’t upload any file that’s already on its servers – and all of the pictures on my smartphone were. When comparing the two versions of some pictures (original and re-upload) I noticed that their MD5 hashes weren’t identical. I can’t explain that, but it looks like the re-uploads lost some of their meta-data.
So just in case you use Dropbox, enabled the auto-upload functionality and plan to use a (foreign / different / whatever ?) SIM card, have a look at your data usage or disconnect the Dropbox app.