On Wed, Jul 3, 2013 at 9:59 AM, Andrew Bialecki <andrew.bialecki@gmail.com> wrote:
2. I'm assuming in our case the cause is incrementing counters because disk reads are part of the write path for counters and are not for appending columns to a row. Does that logic make sense?

That's a pretty reasonable assumption if you are not doing any other reads and you see your disk busy doing non-compaction related reads. :)