whatever it was, the box has recovered after few reboots. the test data is untouched but the logs are wiped. however, this episode makes me reconsider about using it as the only storage media for my files.
after the last reboot (and note: i don't reboot it by keeping the power button pressed, i just give it a push so it can start the safely shutdown sequence) the utelnetd did not start, and dropbear no longer accepted my ssh key.
digging....