[Maas-devel] Appserver & DB Scaling

[Gavin Panella]

On 24 October 2012 13:15, John Arbash Meinel <john at arbash-meinel.com> wrote:
> With 16 Cluster Controllers, we can achieve CPU saturation on the
> Database with a shared Appserver (19.2s rebuild). Moving the appserver
> can relieve some of this overhead, but it adds bandwidth
> considerations between the DB and Appserver. With 'hostnossl'
> separating the appserver actually slows down rebuilding tags because
> the network becomes saturated at 900+Mbps (24.6s). Switching to
> 'hostssl' increases some CPU overhead on the Database machine, but is
> a net win (17.7s).
>
> Enabling a second Appserver is not directly a benefit (19.1s). As a
> quirk of our topology, you can run 1 appserver in 'low cpu high
> bandwidth nossl' mode, and one in 'higher cpu low bandwidth ssl' mode,
> and maximize the DB's available resources (15.1s).

What do the "hostnossl", "hostssl", "low cpu high bandwidth nossl" and
"higher cpu low bandwidth ssl" phrases refer to? PostgreSQL?