I run a TOR relay under the name "torland" (http://torstatus.blutmagie.de/router_detail.php?FP=8d90596192e548c8c00fa9e82759f95b875dc99e). Just today, my relay became marked as a stable tor relay because it has been running non-stop for around two weeks. However, my concern is: I'm going to need to shut my relay down eventually when my computer needs to do a software update, or if my internet connection is turned off for whatever reason. Is there a way I can keep my relay marked as stable when this happens? Thank you.

1 Answer 1


Restarting a relay will not cause it to lose it's Stable flag. Stable doesn't require 100% uptime, it requires that it be up most of the time, so restarting it to apply updates shouldn't cause it to lose it.

From dir-spec.txt:

   "Stable" -- A router is 'Stable' if it is active, and either its Weighted
   MTBF is at least the median for known active routers or its Weighted MTBF
   corresponds to at least 7 days. Routers are never called Stable if they are
   running a version of Tor known to drop circuits stupidly.  (
   through are stupid this way.)

        To calculate weighted MTBF, compute the weighted mean of the lengths
        of all intervals when the router was observed to be up, weighting
        intervals by $\alpha^n$, where $n$ is the amount of time that has
        passed since the interval ended, and $\alpha$ is chosen so that
        measurements over approximately one month old no longer influence the
        weighted MTBF much.

This is by intent, since obviously relays should have some amount of downtime to do sensible things like install software updates.

  • Yes, this just happened and my relay is still marked as stable, thank you. What does being marked as Stable do for my relay? Thank you. Feb 18, 2018 at 9:28
  • Stable simply means that the router is going to be available with high uptime, e.g. that it won't go down every day or similar. Tor uses them for Long Lived Circuits, e.g. circuits which use protocols that normally have long connection times like SSH, IRC or XMPP, unlike HTTP which often has quite short connection times. It's also a requirement for other flags allowing it to be used for other purposes like Guard or HSDir since they require that the relay have good uptime to work well.
    – cacahuatl
    Feb 19, 2018 at 12:17

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