On-Demand MPI Cluster with Python and EC2 (part 1 of 3)
In this post, we will build a 20 node Beowulf cluster on Amazon EC2 and run some computations using both MPI and its Python wrapper pyMPI. This tutorial will only describe how to get the cluster running and show a few example computations. I’ll save detailed benchmarking for a later write-up.
One way to build an MPI cluster on EC2 would be to customize something like Warewulf or rebundle one of the leading linux cluster distributions like Parallel Knoppix or the Rocks Cluster Distribution onto an Amazon AMI. Both of these distros have kernels which should work with EC2. To get things running quickly as a proof of concept, I implemented a “roll-your-own” style cluster based on a Fedora Core 6 AMI managed with some simple Python scripts. I’ve found this approach suitable for running occasional parallel computations on EC2 with 20 nodes and have been running a cluster off and on for several months without any major issues. If you need to run a much larger cluster or require more complex user management, I’d recommend modifying one of the standard distributions. This will save you from some maintenance headaches and give you the additional benefit of the user/developer base for those systems.
The main task I use the cluster for is distributing large matrix computations, which is a problem well suited to existing libraries based on MPI. Depending on your needs, another platform such as Hadoop, Rinda, or cow.py might make more sense. I use Hadoop for some other projects, including MapReduce style tasks with Jython, and highly recommend it. That said, lets start building the MPI cluster…
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