[Mapserver-users] Whole lotta shakin' going on

[Ed McNierney]

Folks -

As I posted on this list a week or so ago, we've migrated TopoZone over
to a 100%-MapServer site.  Everything's been doing fine, but we're still
keeping an eye on things.

About an hour ago I noticed a sudden huge spike in traffic on TopoZone.
At TopoZone we get a lot of users, so together the average usage forms a
very characteristic curve over the course of the day.  Weekdays it
starts climbing in the morning, leveling a bit around midday, reaching a
peak right around 4 PM Eastern time, then falling and climbing to a
lower, secondary peak around 9 - 10 PM Eastern time before dropping to
its 5 AM Eastern time low point.

At about 9:40 PM our traffic suddenly shot up to its highest level since
we made the switch to the MapServer site.  This was very strange.  When
I investigated, I found that actually almost all the traffic was being
handled by one of our eight MapServer systems.  Our data is distributed
geographically across these systems, and it turned out that we were
getting a huge number of requests for maps of the same area.

Hmmmm....  a hacker?  That was my first thought, but it would need to be
someone with a LOT of clear bandwidth.  The log files showed the traffic
was coming from a lot of different clients - an attempt at a coordinated
Denial of Service attack?

A bit more log-sniffing took me here:

http://earthquake.usgs.gov/recenteqsUS/Quakes/nc40146208.htm

There's a "topo map" link in the "Additional Information" section near
the bottom.  Mystery solved.

Things are still quite busy, but they've cooled off a bit.  I'm sure
there will be a bunch of curious users in the morning, too.

The one MapServer system that was taking all the heat was serving an
average of 10 custom topo maps a second over a full 10 minute period.
MapServer was chugging along just fine - the only "problem" was that I
got one complaint from Apache that I might want to increase my
MaxClients setting <g>.

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
Phone: (978) 251-4242  Fax: (978) 251-1396
ed at topozone.com