Re: [sidr] sidr-arch-09 refresh cycle time

[Rob Austein <sra at isc.org>]

[Catching up on back mail while in transit to Hiroshima...]

At Tue, 27 Oct 2009 16:28:57 -0400, Matt Lepinski wrote:
> 
> Here, I understand that "everyone hitting the repository system at once" 
> is a bad outcome regardless of the frequency that we recommend. That is, 
> regardless of whether we recommend "once per day", "once per month", or 
> "eight times daily" we will likely see problems with too much server 
> load at midnight. If anyone can recommend text to avoid this phenomena 
> (i.e., to encourage people to spread out their queries to the repository 
> system), please send text.

FWIW: rcynic has a "jitter" mechanism which delays startup (and thus
the rsync hit on servers) by a pseudo-random amount of time in the
range [0..n], where n defaults to ten minutes.  The important part is
that this behavior is on by default, so a user has to read the
documentation (or at least the usage message) to disable it.  How much
it helps, and whether a different value of n would be better, I dunno,
but it was trivial to implement, and one could easily extend it
slightly to log dire warnings or flat out refuse to run for too-small
values of n.