Hey, I'd really appreciate it if you could send a report of your experiences to linux-ext4@vger.kernel.org. This is the first I've heard of issues with ext4 with EBS, and I'd love to know more. (Also, please mention the kernel version you are using; one possibility is that EC2 kernels tend to lag upstream kernels, and ext4 has had a lot of bug fixes since a RHEL or SLES kernel of 2.6.32/2.6.34 --- upstream is at 2.6.39, and we're about to release version 3.0. :-)
