On 8 Dec 2015, at 10:43, Tom Ritter tom@ritter.vg wrote:
On 7 December 2015 at 13:51, Philipp Winter <phw@nymity.ch mailto:phw@nymity.ch> wrote:
I spent some time improving the existing relay uptime visualisation [0]. Inspired by a research paper [1], the new algorithm uses single-linkage clustering with Pearson's correlation coefficient as distance function. The idea is that relays are grouped next to each other if their uptime (basically a binary sequence) is highly correlated. Check out the following gallery. It contains monthly relay uptime images, dating back to 2007: <https://nymity.ch/sybilhunting/uptime-visualisation/ https://nymity.ch/sybilhunting/uptime-visualisation/>
If you aren't familiar with this type of visualisation: Every image shows the uptime of all Tor relays that were online in a given month. Every row is a consensus and every column is a relay. White pixels mean that a relay was offline and black pixels means that a relay was online. Red pixels are used to highlight suspiciously similar clusters.
That's really cool. It seems to imply that the majority of the tor network stop operating halfway through the month though... Do the other tor graphs take into account hibernating relays? For example, I would expect the time-to-download graph would be somewhat affected: https://metrics.torproject.org/torperf.html?graph=torperf&start=2015-10-... https://metrics.torproject.org/torperf.html?graph=torperf&start=2015-10-01&end=2015-10-31&source=all&filesize=5mb
Hibernating relays run from the start of their first period to gauge load. Then they start at a random time during the day/month, but early enough that they think they'll still use all their bandwidth.
I wonder if we're seeing another phenomenon? (daily / monthly server restarts?) Or we could be seeing hibernation failing to work as intended.
Tim
Tim Wilson-Brown (teor)
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