IBM Spectrum Scale Sharing Nothing Cluster performance tuning guide has been posted and please refer to link before you doing the below change.
Note: If the cluster is not dedicated for Hadoop workloads, take the default value for the above configurations.
For Hadoop-like workloads, one JVM process can open a lot of files. Therefore, tune the ulimit values:
# add the following lines at the end of /etc/security/limits.conf
* soft nofile 65536
* hard nofile 65536
* soft nproc 65536
* hard nproc 65536
The default value is usually 32K. If you see the error “allocate memory”or “unable to create new native thread”, you could try to increase kernel.pid_max by adding “kernel.pid_max=99999” at the end of /etc/sysctl.conf and then “sysctl -p”.