Monthly Archives: September 2016

AWS ElasticMapReduce TaskConfiguration_H2

Avoiding Cluster Slowdowns (AMI 3.0.0) Task JVM Memory Settings Hadoop 2 uses two parameters to configure memory for map and reduce: and, respectively. These replace the single configuration option from previous Hadoop versions: The defaults for these settings per instance type are shown in the following tables. m1.medium Configuration Option Default Value… Read More »

(13: Permission denied) while connecting to upstream:[nginx]

Had an issue getting Fedora 20, Nginx, Node.js, and Ghost (blog) to work. It turns out my issue was due to SELinux. I checked for errors in the SELinux logs: sudo cat /var/log/audit/audit.log | grep nginx | grep denied And found that running the following commands fixed my issue: sudo cat /var/log/audit/audit.log | grep nginx… Read More »

EdgeMAX – Dual WAN Load-Balance Feature

Overview Readers will learn about the WAN load-balance feature between interfaces on the EdgeRouter, based on version EdgeOS v1.4.0 and later. Versions of EdgeOS prior to v1.8.0 only supported 2 WAN interfaces, but in v1.8.0 you can have up to 8. There are a few requirements for this type of configuration: 1) A load-balance section… Read More »

Monitoring Apache Spark (Streaming) with Prometheus

INTRODUCTION As part of our efforts of establishing a robust back-end, one important part of it is monitoring the environment, hosts and services. Lately, we decided to give a try to Prometheus. Prometheus is an “open-source service monitoring system and time series database”, created by SoundCloud. It is a relatively young project, but it’s quickly… Read More »

Monitoring Spark on Hadoop with Prometheus and Grafana

Anyone who has spent time developing Spark applications (or any other distributed application for that matter) has probably wished for some x-ray goggles into the black-box machinery of the framework. While Spark provides a nice and increasingly feature-rich UI for checking on the status of running tasks and even gives statistics on things like runtime,… Read More »