Those links seem to not being working.
link there works: http://ganglia.wikimedia.org/
But that was enough, at least for symptoms. I have no idea what it means.
There's no corresponding admin log for 2:30 UTC....
"New Squids", a clear notch (drastic drop of CPU, load, and network traffic,
almost to zero).
"Apaches", a corresponding halving of CPU, load, and output (but not input)
"MySQL", vast increase (3-5 times) of load, doubling of CPU, but no change
in network traffic (that comes a couple of hours later, probably unrelated,
the admin log shows a copy of db2 to db3).
The MySQL servers that account for the change are ariel, db1, db2, db3, and
db4, with a smaller bump at samuel. The others seem unaffected.