[OSM-dev] Yevaud SSD Drive

[Toby Murray]

On Thu, Apr 12, 2012 at 4:33 PM, John Perrin <john.d.perrin at gmail.com> wrote:
> Hi,
>
> I've posted this question on the OSM Q & A site a well, not sure what the
> best forum for the question is, so please forgive the dual post if you also
> follow that site.
>
> Basically, I was just inquiring into the specific need for the SSD drive on
> the yevaud tile server.  I'm looking to run an OSM tile server that can
> handle roughly 200,000 - 400,000 map views a day and have taken this as a
> good benchmark for the server spec.  However the SSD is half the cost of
> reproducing a server with that spec.  I was just wondering exactly what the
> disk was used for, and why is specifically needed the SSD drive. I can see
> the purchase logged in the server upgrade history, but I can't see any
> reason explaining why it was needed.

See the yearly graph here:
http://munin.openstreetmap.org/openstreetmap/yevaud.openstreetmap/renderd_queue.html
and here:
http://munin.openstreetmap.org/openstreetmap/yevaud.openstreetmap/renderd_processed.html

The second graph had a hiccup in August that makes it kind of hard to
read the other values but at the left edge you can see the render
queue was full for a lot of the time and it was dropping render
requests a lot. Then in May of last year the SSD was installed. Now I
think the only time the render queue gets full is short spikes of peak
load (when OSM hits slashot and the like)

The SSD holds the postgis database that mapnik executes queries
against to pull the data for rendering. Before the SSD, I believe
yevaud was running a fairly beefy RAID 10 so the SSD really did make a
big difference.

Toby