rsync termiates after a while unexpectedly

This is an old question, with limited information, but I think what is happening is not an rsync issue (since rsync won't sigkill itself).

I ran into a similar problem which turned out to be a memory issue. The out of memory management in the kernel determines which process to kill by looking at the amount of virtual memory used divided by total time running.

Rsync can consume lots of memory depending on the size and number of files being transferred, and it will have a low run time value. This increases it's score when the kernel calls select_bad_process().

Check memory usage with a simple script after starting rsync that logs rsync memory usage:

while [ 1 ]; do
  pidstat -r -G rsync >> stat.log
  free >> stat.log
done

Also check dmesg around the time rsync dies, if there are OOM errors you'll see them.