Commands to monitor load and memory for hardware node -virtuozzo
1) vzlist -o laverage,veid
2) vzlist -o ctid,name,laverage,kmemsize -s laverage
This one gives a good overview of the load and memory usage
this comes back to tells you
123 vpsname.com 12.02/7.76/7.07 21272584
3) vcalc -v (vpsid)
4) vmstat vpsid
5) cat /var/log/messages | grep OOM | grep ve=661 | wc -l
here 661 is your vps id.
If there are number of customers complaining for dead services like ftp, http, named and so on
You need to check through this script and ask them to INCREASE the RAM.