We’re using and EBS-backed RAID10 array for MongoDB. This is the only way to get reliable iops on AWS at the moment. Start by creating the volumes. For this example I’ll be creating 5 volumes of 10GB each. EBS volumes can only be attached to instances in the same region and AZ as the volume. Once the volumes are created attach them to the instance. I’ll be using /dev/sd[i-m], though the sd is the only important part.