How can I create multiple identical AWS EC2 server instances with large amounts of persistent data?

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http://serverfault.com – I have a CPU-intensive data-processing application that I want to run across many (~100,000) input files. The application needs a large (~20GB) data file in order to run. What I would like to do is create an EC2 machine image that has my application and associated data files installed boot up a large number (e.g. 100) of instances of this image split my input files up into 100 batches and send one batch to be processed on each instance I am having trouble figuring out the best way to ensure that each instance has access to the large data file. The data file is too big to fit on the root f (HowTos)