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From dyozie <...@git.apache.org>
Subject [GitHub] incubator-hawq-docs pull request #86: HAWQ-1263 - misc doc updates
Date Sat, 14 Jan 2017 01:33:08 GMT
Github user dyozie commented on a diff in the pull request:

    https://github.com/apache/incubator-hawq-docs/pull/86#discussion_r96097864
  
    --- Diff: markdown/install/aws-config.html.md.erb ---
    @@ -14,54 +14,61 @@ For information about Amazon EC2, see the [EC2 User Guide](http://docs.aws.amazo
     
     ## <a id="topic_nhk_df4_2v"></a>Create and Launch HAWQ Instances
     
    -Use the *Amazon EC2 Console* to launch instances and configure, start, stop, and terminate
(delete) virtual servers. When you launch a HAWQ instance, you select and configure key attributes
via the EC2 Console.
    +Use the **Amazon EC2 Console** to launch instances and configure, start, stop, and terminate
(delete) virtual servers. When you launch a HAWQ instance, you select and configure key attributes
via the EC2 Console.
     
     
     ### <a id="topic_amitype"></a>Choose AMI Type
     
    -An Amazon Machine Image (AMI) is a template that contains a software configuration including
the operating system, application server, and applications that best suit your purpose. When
configuring a HAWQ virtual instance, we recommend you use a *hardware virtualized* AMI running
64-bit Red Hat Enterprise Linux version 6.4 or 6.5 or 64-bit CentOS 6.4 or 6.5.  Obtain the
licenses and instances directly from the OS provider.
    +An Amazon Machine Image (AMI) is a template that contains a specific software configuration
including the operating system, application server, and applications that best suit your purpose.
When configuring a HAWQ virtual instance, we recommend that you use a *hardware virtualized*
(HVM) AMI supporting enhanced 10Gbps networking. Ensure the AMI is running 64-bit Red Hat
Enterprise Linux version 6.4 or 6.5 or 64-bit CentOS 6.4 or 6.5.  Obtain the licenses and
instances directly from the OS provider.
     
     ### <a id="topic_selcfgstorage"></a>Consider Storage
    -EC2 instances can be launched as either Elastic Block Store (EBS)-backed or instance
store-backed.  
    +EC2 instances are launched as either Elastic Block Store (EBS)-backed or instance store-backed.
Choose the storage type based on the expected lifetime of your cluster and data.
     
    -Instance store-backed storage is generally better performing than EBS and recommended
for HAWQ's large data workloads. SSD (solid state) instance store is preferred over magnetic
drives.
    +#### <a id="topic_selcfgstorage_instance"></a>Instance Store-Backed
     
    -**Note** EC2 *instance store* provides temporary block-level storage. This storage is
located on disks that are physically attached to the host computer. While instance store provides
high performance, powering off the instance causes data loss. Soft reboots preserve instance
store data. 
    -     
    -Virtual devices for instance store volumes for HAWQ EC2 instance store instances are
named `ephemeralN` (where *N* varies based on instance type). CentOS instance store block
device are named `/dev/xvdletter` (where *letter* is a lower case letter of the alphabet).
    +Use instance store-backed storage for short lived or transient clusters that do not require
long-term persistence of data. While instance store-backed storage is generally better performing
than EBS, it is not recommended for use in a production environment.
    +
    +**Warning**: EC2 instance store provides *temporary* block-level storage. This storage
is located on disks that are physically attached to the host computer. You will lose all instance
store data when the AMI instance is powered off.
    +
    +
    +#### <a id="topic_selcfgstorage_ebs"></a>EBS-Backed
    +EBS volumes are reliable and highly-available. Use EBS-backed storage for longer running
clusters where data must be quickly accessible and requires longer term persistence.
    +
    +
    +#### <a id="topic_selcfgstorage_volume"></a>Volume Types
    +When selecting between HDD and SSD volume types, the trade-off is speed vs. capacity
vs. cost. HDD volumes have greater disk capacity at less performance and cost. SSD (solid
state) volumes are more performant, though costlier and typically with less disk capacity.
     
     ### <a id="topic_cfgplacegrp"></a>Configure Placement Group 
     
    -A placement group is a logical grouping of instances within a single availability zone
that together participate in a low-latency, 10 Gbps network.  Your HAWQ master and segment
cluster instances should support enhanced networking and reside in a single placement group
(and subnet) for optimal network performance.  
    +A placement group is a logical grouping of instances within a single availability zone
that together participate in a low-latency, 10 Gbps network.  We recommend your HAWQ master
and segment cluster instances support enhanced networking and reside in a single placement
group (and subnet) for optimal network performance.
     
     If your Ambari node is not a DataNode, locating the Ambari node instance in a subnet
separate from the HAWQ master/segment placement group enables you to manage multiple HAWQ
clusters from the single Ambari instance.
     
     Amazon recommends that you use the same instance type for all instances in the placement
group and that you launch all instances within the placement group at the same time.
     
    -Membership in a placement group has some implications on your HAWQ cluster.  Specifically,
growing the cluster over capacity may require shutting down all HAWQ instances in the current
placement group and restarting the instances to a new placement group. Instance store volumes
are lost in this scenario.
    +Membership in a placement group has some implications on your HAWQ cluster.  Specifically,
growing the cluster over capacity may require shutting down all HAWQ instances in the current
placement group and restarting the instances in a new placement group. **Warning**: Instance
store volumes are lost in this scenario.
    +
    +**Note**: If you have no tolerance for potential cluster expansion down time, placement
groups may not be a viable option for your HAWQ deployment.
    --- End diff --
    
    "Note: If cluster down time during expansion is not acceptable for your deployment, do
not use placement groups.


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