e8568ce1f0
Modifies doc/source/userdoc/overview.rst. Change-Id: I92d8ec5b079a51b047d498fbb4a2c171446abd19
70 lines
2.7 KiB
ReStructuredText
70 lines
2.7 KiB
ReStructuredText
Getting Started
|
|
================
|
|
|
|
Clusters
|
|
--------
|
|
|
|
A cluster deployed by Savanna consists of node groups. Node groups vary by
|
|
their role, parameters and number of machines. The picture below
|
|
illustrates example of Hadoop cluster consisting of 3 node groups each having
|
|
different role (set of processes).
|
|
|
|
.. image:: ../images/hadoop-cluster-example.jpg
|
|
|
|
Node group parameters include Hadoop parameters like `io.sort.mb` or
|
|
`mapred.child.java.opts`, and several infrastructure parameters like 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
|
|
group, cluster has Hadoop and infrastructure parameters. An
|
|
example of cluster-wide Hadoop parameter is `dfs.replication`. For
|
|
infrastructure an example could be image which will be used to launch cluster
|
|
VMs.
|
|
|
|
Templates
|
|
---------
|
|
|
|
In order to simplify cluster provisioning Savanna employs concept of templates.
|
|
There are two kind of templates: node group template and cluster template. The
|
|
former is used to create node groups, the later - clusters. Essentially
|
|
templates have the very same parameters as corresponding entities. Their aim
|
|
is to remove burden of specifying all the required parameters each time user
|
|
wants to launch a cluster.
|
|
|
|
In the REST interface templates have extended functionality. First you can
|
|
specify node-scoped parameters here, they will work as a defaults for node
|
|
groups. Also with REST interface during cluster creation user can override
|
|
template parameters for both cluster and node groups.
|
|
|
|
Provisioning Plugins
|
|
--------------------
|
|
|
|
A provisioning plugin is a component responsible for provisioning Hadoop
|
|
cluster. Generally each plugin is capable of provisioning a specific Hadoop
|
|
distribution. Also plugin can install management and/or monitoring tools for
|
|
a cluster.
|
|
|
|
Since Hadoop parameters vary depending on distribution and Hadoop version,
|
|
templates are always plugin and Hadoop version specific. A template could not
|
|
be used with plugin/Hadoop version different than ones it was created for.
|
|
|
|
You may find the list of available plugins on that page: :doc:`plugins`
|
|
|
|
Image Registry
|
|
--------------
|
|
|
|
OpenStack starts VMs based on pre-built image with installed OS. The image
|
|
requirements for Savanna depend on plugin and Hadoop version. Some plugins
|
|
require just basic cloud image and install Hadoop on VMs from scratch. Some
|
|
plugins might require images with pre-installed Hadoop.
|
|
|
|
The Savanna Image Registry is a feature which helps filter out images during
|
|
cluster creation. See :doc:`registering_image` for details on how to
|
|
work with Image Registry.
|
|
|
|
Features
|
|
--------
|
|
|
|
Savanna has several interesting features. The full list could be found there:
|
|
:doc:`features`
|