### Please describe the problem.

1 thumb drive became corrupted when using as a server on raspberry pi, and 2 microSD cards when using as a client in my phone. Both happened during syncing largish repository. (corrupted = permanent input/output error)

* Put git annex on my android phone with a 64GB (FAT) micro SD, fired up git annex, it got reported as corrupted half on hour later, reformatting worked but got reported as corrupted again.

* Put git annex assistant on my raspberry pi, one of the thumbdrives in my LVM (ext4) got corrupted shortly after I began using the assistant. I replaced them with a cheap real SSD drive, and had no problem since.

* Put git annex back on my android phone. Kept it going for an extended sync session, but it never started syncing. I kept it going for an hour or so, and my new 32GB microSD (FAT) got corrupted.

The pattern is nothing like proof, but it seems to be too regular to be completely coincidental. The pattern seems to be: ARM + (SDcard|USBstick) + Assistant = drive corruption.

My guess is that the ARM build might have some kind of unlucky write pattern or loop that causes increased wear, but I know very little of the interna.

### What steps will reproduce the problem?

* Get a raspberry pi and a USB stick, or an android phone and a microSD card
* Get an [ARM build of the assistant](https://github.com/tradloff/git-annex-RPi)
* Sync a largish (12GB) repository

### What version of git-annex are you using? On what operating system?

4.20131002 on the pi, 20131024 for the 32GB SD, and 20131015 for the 64GB SD.

### Please provide any additional information below.

[[!format sh """
# If you can, paste a complete transcript of the problem occurring here.
# If the problem is with the git-annex assistant, paste in .git/annex/daemon.log

Unfortunately, daemon.log was unrecoverable along with the other files on the SD card.

I can try and autosync the daemon.log somewhere if I happen to come along a bunch of scrap flash storage (not impossible).

# End of transcript or log.
"""]]