Can we add more Amazon Elastic Mapreduce instances into an existing Amazon Elastic Mapreduce instances?

Question

I am new to Amazon Services and facing some issues.

Suppose I am running some Job Flow on Amazon Elastic Mapreduce with total 3 instances. While running my job flow on i

Answer 1

It's important to note that CORE instance-group instances can not be reduced since they participate as data nodes. They can be increased only. TASK instances only do processing and can be increased and reduced.

Answer 2

Yes, you can do this with the command line tool

to add more instances to the core group:

elastic-mapreduce --modify-instance-group CORE --instance-count 40

To create a task group (no datanodes), with 40 instances:

elastic-mapreduce --add-instance-group TASK --instance-count 40 --instance-type c1.medium