Ask writes: > On Oct 14, 2007, at 4:14 PM, Guillaume Filion wrote: >> The problem is that it doesn't support the "noselect" option when >> adding a peer: >> http://fortytwo.ch/mailman/pipermail/timekeepers-dev/2007/000006.html
>Right. >> I can't remember why we needed it thought... > 1) We can't use the monitored servers to set the time on the > monitoring server. > 2) ntpd doesn't deal nicely with a thousand servers in the selection > algorithm. IIRC, just a couple of years ago with circa 100 servers in the pool we discovered that ntpd's selection algorithm doesn't work well with a large number of servers. Up until then it was being used, essentially counting the number of times the server was deselected by looking at the first punctuation character in the "ntpq -c peers" output, to compute the score, right? Problem is, ntpd's selection algorithm works pretty well with a handful of servers, but it gets way too aggressive with reselecting and rejecting on the arrival of every reply from a server. That's not automatically a bad thing: If you've got 1000 servers, you have no problem rejecting 3/4 of them because you've still got 250 left! But the falseticker logic is really getting out of hand at that point. I don't think that automatically rules it out, I believe that with some modification the selection algorithm could do the right thing for large numbers of servers. I think that overall the current monitoring scheme is excellent. The graphs and trendlines driven from them are really truly useful for server maintainers. Tim. _______________________________________________ timekeepers mailing list [email protected] https://fortytwo.ch/mailman/cgi-bin/listinfo/timekeepers
