Tag Archives: Hadoop Tuning

Hadoop, Java and HTTPD and /etc/security/limits.d/ nproc/pid-max

After successfully running a Large Hadoop Cluster for a period of time. I started to notice strange things occurring initially with the MapReduce PI example task where tasks would be marked as failed. When looking more closely and attempting to logon/su/ssh to a machine with the userid that was running the job the sshd/su would return: -bash:… Read More »

Hadoop and ip_conntrack: table full, dropping packet

I’m pretty sure many folks have seen this specific error across multiple different linux systems specifically when iptables is enabled and the OS has thousands of connections coming in second. In my case I ran into this Examples of this are with Hadoop NameNode. Someone accidentally executed iptables -L to try to get a list… Read More »

Hadoop and Redhat System Tuning /etc/sysctl.conf

One of the most overlooked things after setting up a Hadoop cluster is probably OS System Tuning. This entry will cover /etc/sysctl.conf aka the Linux Kernel Params that can be tuned. /etc/sysctl.conf: ## ALWAYS INCREASE KERNEL SEMAPHORES especially IF using IBM JDK with SharedClassCache also a separate discussion # Controls the default maxmimum size of… Read More »

Why now?

What is the GSpot Tech Blog! It’s a place for me to discuss technology I’ve worked with over many years. So after working as a Technology Systems Engineer for almost 20 years. I decided it’s time to create a blog to publish some of my personal ideas regarding technology. All opinions are my own and… Read More »