I observed something similar today. It was basically as you described for the previous cases you observed, where there was a storm of about 10 times more TAP handshakes than usual. My middle relay is pretty small, limited to 1.1Mbit/s, and until this point it wasn't even saturating that. Then this storm came in and saturated it for less than half a day, and then it stopped. My consensus weight went up during this time, so there is a higher level of residual traffic now than before it started, but the extreme event seems to done. It's strange to me that during the storm, the downstream traffic was much greater than the upstream. Any idea what could have been going on during that time? Why would my relay be receiving a bunch of data that it didn't pass on? The discrepancy seems to be too high for it to downloading directory information.
The fingerprint is 7552CA84FB125059DC2959A6BE01A6A8107B3523 and here are the log entries from before, during and after:
Sep 06 13:40:04.000 [notice] Heartbeat: Tor's uptime is 11 days 18:00 hours, with 34 circuits open. I've sent 3.52 GB and received 3.52 GB.
Sep 06 13:40:04.000 [notice] Average packaged cell fullness: 96.735%
Sep 06 13:40:04.000 [notice] TLS write overhead: 6%
Sep 06 13:40:04.000 [notice] Circuit handshake stats since last time: 1948/1949 TAP, 645/645 NTor.
Sep 06 19:40:04.000 [notice] Heartbeat: Tor's uptime is 12 days 0:00 hours, with 878 circuits open. I've sent 3.64 GB and received 3.65 GB.
Sep 06 19:40:04.000 [notice] Average packaged cell fullness: 95.657%
Sep 06 19:40:04.000 [notice] TLS write overhead: 7%
Sep 06 19:40:04.000 [notice] Circuit handshake stats since last time: 16759/16957 TAP, 540/540 NTor.
Sep 07 00:12:04.000 [notice] New control connection opened.
Sep 07 00:25:03.000 [notice] New control connection opened.
Sep 07 00:31:42.000 [notice] New control connection opened.
Sep 07 01:14:06.000 [notice] New control connection opened.
Sep 07 01:40:04.000 [notice] Heartbeat: Tor's uptime is 12 days 6:00 hours, with 161 circuits open. I've sent 4.03 GB and received 4.51 GB.
Sep 07 01:40:04.000 [notice] Average packaged cell fullness: 93.753%
Sep 07 01:40:04.000 [notice] TLS write overhead: 7%
Sep 07 01:40:04.000 [notice] Circuit handshake stats since last time: 36498/611731 TAP, 832/867 NTor.
Sep 07 07:40:04.000 [notice] Heartbeat: Tor's uptime is 12 days 12:00 hours, with 24 circuits open. I've sent 4.44 GB and received 6.22 GB.
Sep 07 07:40:04.000 [notice] Average packaged cell fullness: 93.604%
Sep 07 07:40:04.000 [notice] TLS write overhead: 8%
Sep 07 07:40:04.000 [notice] Circuit handshake stats since last time: 27191/1548070 TAP, 1261/1353 NTor.
Sep 07 13:34:25.000 [notice] New control connection opened.
Sep 07 13:40:04.000 [notice] Heartbeat: Tor's uptime is 12 days 18:00 hours, with 19 circuits open. I've sent 4.61 GB and received 6.38 GB.
Sep 07 13:40:04.000 [notice] Average packaged cell fullness: 93.745%
Sep 07 13:40:04.000 [notice] TLS write overhead: 8%
Sep 07 13:40:04.000 [notice] Circuit handshake stats since last time: 1803/1803 TAP, 385/385 NTor.