Application Testing When you are testing a new application in order to prepare

Application testing when you are testing a new

This preview shows page 141 - 143 out of 395 pages.

Application Testing When you are testing a new application in order to prepare it for launch in a production environment, you can run the entire cluster (master, core, and task instance groups) as Spot Instances to reduce your testing costs. Calculating the Required HDFS Capacity of a Cluster The amount of HDFS storage available to your cluster depends on these factors: The number of EC2 instances used for core nodes. The capacity of the EC2 instance store for the instance type used. For more information on instance store volumes, see Amazon EC2 Instance Store in the Amazon EC2 User Guide for Linux Instances . The number and size of EBS volumes attached to core nodes. A replication factor, which accounts for how each data block is stored in HDFS for RAID-like redundancy. By default, the replication factor is three for a cluster of 10 or more core nodes, two for a cluster of 4-9 core nodes, and one for a cluster of three or fewer nodes. To calculate the HDFS capacity of a cluster, for each core node, add the instance store volume capacity to the EBS storage capacity (if used). Multiply the result by the number of core nodes, and then divide the total by the replication factor based on the number of core nodes. For example, a cluster with 10 core nodes of type i2.xlarge, which have 800 GB of instance storage without any attached EBS volumes, has a total of approximately 2,666 GB available for HDFS (10 nodes x 800 GB ÷ 3 replication factor). If the calculated HDFS capacity value is smaller than your data, you can increase the amount of HDFS storage in the following ways: 135
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Amazon EMR Management Guide Configure Cluster Logging and Debugging Creating a cluster with additional EBS volumes or adding instance groups with attached EBS volumes to an existing cluster Adding more core nodes Choosing an EC2 instance type with greater storage capacity Using data compression Changing the Hadoop configuration settings to reduce the replication factor Reducing the replication factor should be used with caution as it reduces the redundancy of HDFS data and the ability of the cluster to recover from lost or corrupted HDFS blocks. Configure Cluster Logging and Debugging One of the things to decide as you plan your cluster is how much debugging support you want to make available. When you are first developing your data processing application, we recommend testing the application on a cluster processing a small, but representative, subset of your data. When you do this, you will likely want to take advantage of all the debugging tools that Amazon EMR offers, such as archiving log files to Amazon S3. When you've finished development and put your data processing application into full production, you may choose to scale back debugging. Doing so can save you the cost of storing log file archives in Amazon S3 and reduce processing load on the cluster as it no longer needs to write state to Amazon S3.
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  • Spring '12
  • LauraParker
  • Amazon Web Services, Amazon Elastic Compute Cloud

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