最快/最好的方式在S3到EC2之间复制数据？

I have a fairly large amount of data (~30G, split into ~100 files) I'd like to transfer between S3 and EC2: when I fire up the EC2 instances I'd like to copy the data from S3 to EC2 local disks as quickly as I can, and when I'm done processing I'd like to copy the results back to S3.I have a fairly large amount of data (~30G, spl