[ris-int] IPv6 updates plots
Shane Kerr shane at ripe.net
Tue Aug 31 09:54:35 CEST 2004
James Aldridge wrote: > Take a look at http://www.ris.ripe.net/ipv6-updates/all/ (or any of the > individual RRC's plots) and you'll see a certain periodicity about the graph. > It seems that the RRD is only getting about half the data: > > 5 minutes and 35 minutes past each hour: > > weesp runs the "collect" script and pushes the raw files to halfweg. > > 0 minutes past each hour: > > halfweg runs the "ipv6-updates/update.sh" script looking for files > from the "previous hour" (date -d "1 hour ago" +"%Y%m%d.%H"). > However, at this time, only files up to the last run of > "collect" (25 minutes earlier) are present - YYYYMMDD.HH00 to > YYYYMMDD.HH35. > > Next time "update.sh" runs, an hour later, it again only looks > at files from the previous hour (and not the missing files > from the hour before that). Data from the last 25 minutes of > each hour are never inserted into the RRD. > > A solution to this would be for risops at halfweg's crontab to run the > "ipv6-updates/update.sh" sufficiently long after 5 minutes past the hour for > the "collect" run on weesp to have pushed all the previous hour's files to > halfweg. > > Thoughts? In general I think that modifying timing of various jobs is the wrong tactic for dealing with timing problems. If you have a dependency between two tasks, best to make it explicit. In the world of Unix and cron, the way to do this is to make a simple script that runs the two commands in order, one after the other. If the commands are running on separate boxes, then the easiest solution is to set up a provider/consumer system where one box touches a file when the data is ready, and the other deletes it when used. In the halfweg/weesp situation, "collect" would touch a file when the data has arrived, and "update.sh" would check for this. We can run "update.sh" every minute (or every 5 minutes if we're squeemish) in this case, reducing the latency to the absolute minimum. -- Shane Kerr RIPE NCC
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