From c2ea4fa572b97ed6d73c8fbf745d780dd335ed22 Mon Sep 17 00:00:00 2001 From: Michael McCune Date: Mon, 31 Aug 2015 18:49:12 -0400 Subject: [PATCH] Updating userdoc overview * formatted text for 79 chars * minor grammar fixes Change-Id: Ib68ebfc0cfd2d9cdb987b60f39347a96c5873741 Partial-Bug: 1490687 --- doc/source/userdoc/overview.rst | 60 +++++++++++++++++---------------- 1 file changed, 31 insertions(+), 29 deletions(-) diff --git a/doc/source/userdoc/overview.rst b/doc/source/userdoc/overview.rst index 92ddea00..1d96e4df 100644 --- a/doc/source/userdoc/overview.rst +++ b/doc/source/userdoc/overview.rst @@ -4,49 +4,50 @@ Getting Started 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 -illustrates an example of a Hadoop cluster consisting of 3 node groups each having a -different role (set of processes). +illustrates an example of a Hadoop cluster consisting of 3 node groups each +having a 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 the flavor -for VMs or storage location (ephemeral drive or Cinder volume). +Node group parameters include Hadoop parameters like ``io.sort.mb`` or +``mapred.child.java.opts``, and several infrastructure parameters like the +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, a cluster has Hadoop and infrastructure parameters. An -example of a cluster-wide Hadoop parameter is `dfs.replication`. For +group, a cluster has data processing framework and infrastructure parameters. +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 VMs. Templates --------- -In order to simplify cluster provisioning Sahara employs the concept of templates. -There are two kinds of templates: node group templates and cluster templates. The -former is used to create node groups, the latter - clusters. Essentially -templates have the very same parameters as corresponding entities. Their aim -is to remove the burden of specifying all of the required parameters each time a user -wants to launch a cluster. +In order to simplify cluster provisioning sahara employs the concept of +templates. There are two kinds of templates: node group templates and +cluster templates. The former is used to create node groups, the latter +- clusters. Essentially templates have the very same parameters as +corresponding entities. Their aim is to remove the burden of specifying all +of the required parameters each time a 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 the REST interface, during cluster creation a user can override -template parameters for both cluster and node groups. +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 template parameters for both cluster and node groups. Provisioning Plugins -------------------- -A provisioning plugin is a component responsible for provisioning a Hadoop -cluster. Generally each plugin is capable of provisioning a specific Hadoop -distribution. Also the plugin can install management and/or monitoring tools for -a cluster. +A provisioning plugin is a component responsible for provisioning a data +processing cluster. Generally each plugin is capable of provisioning a +specific data processing framework or Hadoop distribution. Also the plugin +can install management and/or monitoring tools for a cluster. -Since Hadoop parameters vary depending on distribution and the Hadoop version, -templates are always plugin and Hadoop version specific. A template cannot -be used if the plugin/Hadoop versions are different than the ones they were created for. +Since framework configuration parameters vary depending on the distribution +and the version, templates are always plugin and version specific. A template +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` @@ -54,13 +55,14 @@ Image Registry -------------- 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 -require just a basic cloud image and will install Hadoop on the VMs from scratch. Some -plugins might require images with pre-installed Hadoop. +requirements for sahara depend on the plugin and data processing framework +version. Some plugins require just a basic cloud image and will install the +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 -cluster creation. See :doc:`registering_image` for details on how to -work with Image Registry. +cluster creation. See :doc:`registering_image` for details on how to work +with Image Registry. Features --------