On Wed, Apr 29, 2015 at 10:51 AM, <m.roth at 5-cent.us> wrote: >> The server in this case isn't a Linux box with an ext4 file system - so >> that won't help ... >> > What kind of filesystem is it? I note that xfs also has barrier as a mount > option. The server is a NetApp FAS6280. It's using NetApp's filesystem. I'm almost certain it's none of the common Linux ones. (I think they call it WAFL IIRC.) Either way, we do the NFS mount read-only, so write barriers don't even come into play. E.g., with your original example, if we unzipped something, we'd have to write to the local disk. Furthermore, in "low load" situations, the NetApp read latency stays low, and the 5/6 performance is fairly similar. It's only when the workload gets high, and it turn this "aggressive" demand is placed on the NetApp, that we in turn see overall decreased performance. Thanks for the thoughts!