Here are the instructions to restart nds2 (ref. this elog)
1. Log in to megatron
2. Kill all the nds2 related processes
megatron> ps -def | grep nds2
megatron> sudo kill (process number)
megatron> sudo kill -9 (process number) # if the above did not kill a process, force kill
3. Become nds2mgr
megatron> sudo su nds2mgr
4. Go to nds2mgr folder
cd /home/nds2mgr/nds2-megatron
5. Confirm nds2 is not running
megatron> sudo /etc/init.d/nds2 stop
Shutting down nds2: No nds2 found running; none killed.
6. Run nds2
megatron> sudo /etc/init.d/nds2 start
Starting nds2: Clear all segments...