Managing Hosts

Cloudera Manager provides a number of features that let you configure and manage the hosts in your clusters.

The Hosts page has the following sections:

Status

You can view summary information about the hosts managed by Cloudera Manager. You can view information for all hosts, the hosts in a cluster, or individual hosts.

Viewing All Hosts

To display summary information about all the hosts managed by Cloudera Manager, click Hosts > All Hosts in the left menu. The All Hosts page displays with a list of all the hosts managed by Cloudera Manager.

The list of hosts shows the overall status of the Cloudera Manager-managed hosts in your cluster.
  • The information provided varies depending on which columns are selected. To change the columns, click the Columns: n Selected drop-down and select the checkboxes next to the columns to display.
  • Click to the left of the number of roles to list all the role instances running on that host.
  • Filter the hosts list by entering search terms (hostname, IP address, or role) in the search box separated by commas or spaces. Use quotes for exact matches (for example, strings that contain spaces, such as a role name) and brackets to search for ranges. Hosts that match any of the search terms are displayed. For example:
    hostname[1-3], hostname8 hostname9, "hostname.example.com"
    hostname.example.com “HDFS DataNode”
  • You can also search for hosts by selecting a value from the facets in the Filters section at the left of the page.
  • If the agent heartbeat and health status properties are configured as follows:
    • Send Agent heartbeat every x
    • Set health status to Concerning if the Agent heartbeats fail y
    • Set health status to Bad if the Agent heartbeats fail z
    The value v for a host's Last Heartbeat facet is computed as follows:
    • v < x * y = Good
    • v >= x * y and <= x * z = Concerning
    • v >= x * z = Bad

Viewing the Hosts in a Cluster

Do one of the following:
  • Select Clusters > Cluster name > Hosts.
  • In the Home screen, click in a full form cluster table.
The All Hosts page displays with a list of the hosts filtered by the cluster name.

Viewing Individual Hosts

You can view detailed information about an individual host—resources (CPU/memory/storage) used and available, which processes it is running, details about the host agent, and much more—by clicking a host link on the All Hosts page.

Configuration

The Configuration tab lets you set properties related to parcels and to resource management, and also monitoring properties for the hosts under management.

The configuration settings you make here will affect all your managed hosts. You can also configure properties for individual hosts by clicking on the host in the All Hosts page, which will override the global properties set here).

To edit the default configuration properties for hosts, click the Configuration tab.

Roles

Role Assignments

You can view the assignment of roles to hosts as follows:
  1. In the left menu, click Hosts > Roles.
  2. Click a cluster name or All Clusters.

Disks Overview

In the left menu, click Hosts > Disks Overview to display an overview of the status of all disks in the deployment. The statistics exposed match or build on those in iostat, and are shown in a series of histograms that by default cover every physical disk in the system.

Adjust the endpoints of the time line to see the statistics for different time periods. Specify a filter in the box to limit the displayed data. For example, to see the disks for a single rack rack1, set the filter to: logicalPartition = false and rackId = "rack1" and click Filter. Click a histogram to drill down and identify outliers. Mouse over the graph and click to display additional information about the chart.

Host Templates

The Host Templates page lets you create and manage host templates, which provide a way to specify a set of role configurations that should be applied to a host.

This greatly simplifies the process of adding new hosts, because it lets you specify the configuration for multiple roles on a host in a single step, and then (optionally) start all those roles.

To access the Host Templates page, click Hosts > Host Templates in the left menu.

Stopping All the Roles on a Host

You can stop all of the roles on a host from the Hosts page.

Minimum Required Role: Operator (also provided by Configurator, Cluster Administrator, Full Administrator)

  1. In the left menu, click Clusters > Hosts or Hosts > All Hosts.
  2. Select one or more hosts on which to stop all roles.
  3. Select Actions for Selected > Stop Roles on Hosts.

Starting All the Roles on a Host

You can start all the roles on a host from the Hosts page.

Minimum Required Role: Operator (also provided by Configurator, Cluster Administrator, Full Administrator)

  1. Click the Hosts tab.
  2. Select one or more hosts on which to start all roles.
  3. Select Actions for Selected > Start Roles on Hosts.