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Installation
The Apache Ambari project is aimed at making Hadoop management simpler by developing software for provisioning, managing, and monitoring Apache Hadoop clusters. Ambari provides an intuitive, easy-to-use Hadoop management web UI backed by its RESTful APIs.
Ambari enables System Administrators to:
Ambari provides a step-by-step wizard for installing Hadoop services across any number of hosts. Ambari handles configuration of Hadoop services for the cluster. Manage a Hadoop Cluster Ambari provides central management for starting, stopping, and reconfiguring Hadoop services across the entire cluster.
Ambari provides a dashboard for monitoring health and status of the Hadoop cluster. Ambari leverages Ganglia for metrics collection. Ambari leverages Nagios for system alerting and will send emails when your attention is needed (e.g., a node goes down, remaining disk space is low, etc). Ambari enables Application Developers and System Integrators to:
Easily integrate Hadoop provisioning, management, and monitoring capabilities to their own applications with the Ambari REST APIs.
Cloudera Manager is the industry's standard management application for Apache Hadoop. With Cloudera Manager, you can easily deploy and centrally operate the complete Hadoop stack. The application automates the installation process, reducing deployment time from weeks to minutes; gives you a cluster-wide, real-time view of nodes and services running; provides a single, central console to enact configuration changes across your cluster; and incorporates a full range of reporting and diagnostic tools to help you optimize performance and utilization.
The Cloudera Manager Server hosts the Admin Console Web Server and the application logic. It is responsible for installing software, configuring, starting, and stopping services, and managing the cluster on which the services run. Heartbeats are a primary communication mechanism in Cloudera Manager. By default the Agents send heartbeats every 15 seconds to the Cloudera Manager Server. However, to reduce user latency the frequency is increased when state is changing. The Cloudera Manager Server maintains the state of the cluster. This state can be divided into two categories: "model" and "runtime", both of which are stored in the Cloudera Manager Server database.
In a non-Cloudera Manager managed cluster, you most likely start a role instance using an init script, for example, service hadoop-hdfs-datanode start. In a Cloudera Manager managed cluster you can only start or stop services via Cloudera Manager. Cloudera Manager uses an open source supervisor called supervisord that takes care of redirecting log files, notifying of process failure, setting the effective user ID of the calling process to the right user, and so forth. Cloudera Manager supports automatically restarting a crashed process. It will also flag a role instance with a bad state if it crashes repeatedly right after start up.
A major function of Cloudera Manager is to distribute and activate software in your cluster. Cloudera Manager supports two software distribution formats: packages and parcels.
There are a few notable differences between parcels and packages:
- Parcels are self-contained and installed in a versioned directory. This means that multiple versions of a given parcel can be installed "side-by-side". You can then designate one of these installed versions as the "active" one. With traditional packages, only one package can be installed at a time so there's no distinction between what's "installed" and what's "active".
- Parcels can be installed at any location in the filesystem.