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Michael McCune 2015-08-31 18:49:12 -04:00
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@ -4,49 +4,50 @@ Getting Started
Clusters Clusters
-------- --------
A cluster deployed by Sahara consists of node groups. Node groups vary by A cluster deployed by sahara consists of node groups. Node groups vary by
their role, parameters and number of machines. The picture below their role, parameters and number of machines. The picture below
illustrates an example of a Hadoop cluster consisting of 3 node groups each having a illustrates an example of a Hadoop cluster consisting of 3 node groups each
different role (set of processes). having a different role (set of processes).
.. image:: ../images/hadoop-cluster-example.jpg .. image:: ../images/hadoop-cluster-example.jpg
Node group parameters include Hadoop parameters like `io.sort.mb` or Node group parameters include Hadoop parameters like ``io.sort.mb`` or
`mapred.child.java.opts`, and several infrastructure parameters like the flavor ``mapred.child.java.opts``, and several infrastructure parameters like the
for VMs or storage location (ephemeral drive or Cinder volume). flavor for VMs or storage location (ephemeral drive or cinder volume).
A cluster is characterized by its node groups and its parameters. Like a node A cluster is characterized by its node groups and its parameters. Like a node
group, a cluster has Hadoop and infrastructure parameters. An group, a cluster has data processing framework and infrastructure parameters.
example of a cluster-wide Hadoop parameter is `dfs.replication`. For An example of a cluster-wide Hadoop parameter is ``dfs.replication``. For
infrastructure, an example could be image which will be used to launch cluster infrastructure, an example could be image which will be used to launch cluster
VMs. VMs.
Templates Templates
--------- ---------
In order to simplify cluster provisioning Sahara employs the concept of templates. In order to simplify cluster provisioning sahara employs the concept of
There are two kinds of templates: node group templates and cluster templates. The templates. There are two kinds of templates: node group templates and
former is used to create node groups, the latter - clusters. Essentially cluster templates. The former is used to create node groups, the latter
templates have the very same parameters as corresponding entities. Their aim - clusters. Essentially templates have the very same parameters as
is to remove the burden of specifying all of the required parameters each time a user corresponding entities. Their aim is to remove the burden of specifying all
wants to launch a cluster. of the required parameters each time a user wants to launch a cluster.
In the REST interface, templates have extended functionality. First you can In the REST interface, templates have extended functionality. First you can
specify node-scoped parameters here, they will work as a defaults for node specify node-scoped parameters here, they will work as defaults for node
groups. Also with the REST interface, during cluster creation a user can override groups. Also with the REST interface, during cluster creation a user can
template parameters for both cluster and node groups. override template parameters for both cluster and node groups.
Provisioning Plugins Provisioning Plugins
-------------------- --------------------
A provisioning plugin is a component responsible for provisioning a Hadoop A provisioning plugin is a component responsible for provisioning a data
cluster. Generally each plugin is capable of provisioning a specific Hadoop processing cluster. Generally each plugin is capable of provisioning a
distribution. Also the plugin can install management and/or monitoring tools for specific data processing framework or Hadoop distribution. Also the plugin
a cluster. can install management and/or monitoring tools for a cluster.
Since Hadoop parameters vary depending on distribution and the Hadoop version, Since framework configuration parameters vary depending on the distribution
templates are always plugin and Hadoop version specific. A template cannot and the version, templates are always plugin and version specific. A template
be used if the plugin/Hadoop versions are different than the ones they were created for. cannot be used if the plugin, or framework, versions are different than the
ones they were created for.
You may find the list of available plugins on that page: :doc:`plugins` You may find the list of available plugins on that page: :doc:`plugins`
@ -54,13 +55,14 @@ Image Registry
-------------- --------------
OpenStack starts VMs based on a pre-built image with an installed OS. The image OpenStack starts VMs based on a pre-built image with an installed OS. The image
requirements for Sahara depend on the plugin and Hadoop version. Some plugins requirements for sahara depend on the plugin and data processing framework
require just a basic cloud image and will install Hadoop on the VMs from scratch. Some version. Some plugins require just a basic cloud image and will install the
plugins might require images with pre-installed Hadoop. framework on the VMs from scratch. Some plugins might require images with
pre-installed frameworks or Hadoop distributions.
The Sahara Image Registry is a feature which helps filter out images during The Sahara Image Registry is a feature which helps filter out images during
cluster creation. See :doc:`registering_image` for details on how to cluster creation. See :doc:`registering_image` for details on how to work
work with Image Registry. with Image Registry.
Features Features
-------- --------