Comment 1 for bug 1624591

This could be done on all machines that house disks by setting the system scheduler to cfq, it looks like changing it per-disk, permanently will be a bit of a hack with a service to write `cfq` to the scheduler file. On the other hand, according to this (http://www.ilsistemista.net/index.php/linux-a-unix/38-linux-i-o-schedulers-benchmarked-anticipatory-vs-cfq-vs-deadline-vs-noop.html) somewhat older benchmark, cfq vs deadline isn't a huge performance killer unless using direct-io in which case deadline performs a bit better.

@elmo how would you feel about the ceph[-osd] units having the default scheduler be cfq instead of deadline?