Misc. server admin

change limit of number of files opened:

check current setting: ulimit -n.

To set a specific limit, add these lines to /etc/security/limits.conf:

*           soft    nofile          655350
*           hard    nofile          655350

enable port forwarding to directly access servers

as root, enable direct access to 10.1.255.190 (which is on a subnetwork hosted by biocluster):

iptables -t nat -A PREROUTING -p tcp --dport 8010 -j DNAT --to-destination 10.1.255.190:22
iptables -t nat -A POSTROUTING -j MASQUERADE
iptables -A FORWARD -p tcp -d 10.1.255.190 --dport 22 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

start NFS server on Ubuntu:

sudo systemctl start nfs-kernel-server.service

change SGE queue settings:

change h_vmem total limit on each node. qconf -me NODE and then modify complex_values h_vmem=1200G Make the value larger will allow java virtual machine's initial peak RAM usage. The load is then controlled by mem_free parameter.