I'd like to ask what is the best options of separating commit log and data on Amazon m1.xlarge instance, given 4x420 Gb attached storages and EBS volume ?

As far as I understand, the EBS is not the choice and it's recomended to use attached storages instead.
Is it better to combine 4 ephemeral drives in 2 raid0 (or raid1 ?), and store data on the first and commit log on the second? Or may be trying other combinations like 1 attached storage for commit log, and 3 others grouped in raid0 for data?

Thank you.