Question

I’m trying to get set up on the Amazon Cloud to run some hadoop MapReduce jobs but I’m struggling to successfully create a cluster. I have downloaded the ec2 files, have my certificates and keypair file, but I believe it’s the AMIs that are causing me trouble. If I’m trying to run a cluster with a master node and n slave nodes, I start n+1 instances using standard compatible AMIs and then run the code “hadoop-ec2 launch-cluster name n” in the terminal. The master node is successful, but I get an error when the slave nodes start to launch, saying “missing parameter -h (AMI missing)” and I’m not entirely sure how to progress.

Also, some of my jobs will require an alteration in hadoops parameter settings (specifically the mapred-site.xml config file), is it possible to alter this file, and if so, how do I gain access to it? Is hadoop already installed on amazon machines, with this file accessible and alterable?

Thanks

Answer 1

Have you tried Amazon Elastic MapReduce? This is a simple API that brings up Hadoop clusters of a specified size on demand.

That’s easier then to create own cluster manually.

But once the jobflow is finished by default it shuts the cluster down, leaving you with outputs on S3. If what you need is simply to do some crunching, this may be the way to go.

In case you need HDFS contents stored permanently (e.g. if you are running HBase on top of Hadoop) you may actually need own cluster on EC2. In this case you may find Cloudera’s distribution of Hadoop for Amazon EC2 useful.

Altering Hadoop configuration on nodes it will start is possible using EC2 Bootstrap Actions:

Q: How do I configure Hadoop settings for my job flow?

The Elastic MapReduce default Hadoop configuration is appropriate for most workloads. However, based on your job flow’s specific memory and processing requirements, it may be appropriate to tune these settings. For example, if your job flow tasks are memory-intensive, you may choose to use fewer tasks per core and reduce your job tracker heap size. For this situation, a pre-defined Bootstrap Action is available to configure your job flow on startup. See the Configure Memory Intensive Bootstrap Action in the Developer’s Guide for configuration details and usage instructions. An additional predefined bootstrap action is available that allows you to customize your cluster settings to any value of your choice. See the Configure Hadoop Bootstrap Action in the Developer’s Guide for usage instructions.

About the way you are starting the cluster, please clarify:

If I’m trying to run a cluster with a master node and n slave nodes, I start n+1 instances using standard compatible AMIs and then run the code "hadoop-ec2 launch-cluster name n" in the terminal. The master node is successful, but I get an error when the slave nodes start to launch, saying "missing parameter -h (AMI missing)" and I’m not entirely sure how to progress.

How exactly you are trying start it? What exactly AMIs are you using?