Copy large file to watch = Loose all files (basically factory reset)

So the other day I copied a >4GB file to my watch...

At 4 GB the file copy died, the file was listed in the path I was copying to it at exactly 4GB...

I couldn't delete it, or do anything with other files on the watch.

I unplugged the watch and it was stuck at the charging screen.

After a while it reset by itself.

Watch face had been reset, activities, GPS Maps were gone etc...
I plugged it in an ALL files were gone from the watch!

Seriously, I wish GARMIN exposed the file system directly (as they do with other watches e.g Instinct Solar) instead of MTP rubbish..
This would not have this issue as the file system would prevent you copying a file that is too big and Windows would be aware of this before it even starts copying!
Also as an added benefit the transfer speed would be way faster.
What is the point of MTP on this watch anyway??? ... this is really so that the device can access the storage while the computer can... but you can't do that anyway!

0 muppetman over 4 years ago

It sounds like you've found a very crazy corner case (no one was expecting a 4+ GB file copy) which is unfortunate. Hopefully they can fix this bug.

However there's a point to MTP - it "hides" the underlying filesystem of devices. Who knows what the actual format of a Garmin Watch is. Is it FAT32? Is it XFS? Is it EXT4? With MTP you don't have to care. You don't need a Mac driver for XFS/EXT4 etc etc. You also don't need to worry about users unplugging the watch when a file is halfway written - MTP takes care of that for you. No more having to unmount before unplug etc.

So yea, you've found a crappy corner case, but I think MTP is the right choice for their watches.

0 i00 over 4 years ago in reply to muppetman

Yep ... I know all the advantages and disadvantages ... but they should have handled this case - just make the file copy fail at 4GB and delete the file from the device rather than stuff the internal file system of the watch!

Also I don't think it is that unreasonable for a file to be > 4GB since the file I was trying to copy was a converted OpenMap of the entire EU! (yes I know I could do them in regions, but it didn't occur to me that copying this would stuff up my device till afterwards)

0 TobiasLj over 4 years ago in reply to i00

i00 said:
but they should have handled this case

I did a quick "google" on mtp 4gb and it looks like it is not uncommon and it some even say that it is Microsoft who has implemented the transfer of large files wrong. Something related to separate APIs for large files since the MTP standard use a 32 bit integer for file size...

0 -- over 4 years ago in reply to i00

I hope you got your watch working again. Perhaps a strange thing to say, but thank you for this warning, I'll keep this size limitation in mind.

0 i00 over 4 years ago in reply to TobiasLj

Checked MTP transfer of the same file to my phone.. no problems

Tried transferring it to an old camera.. it cut out at 4 gigs.. the file was not there afterwards, but it did not corrupt the storage, or occupy space... Just like should happen with the watch