Xmon 4.3 - serious RRD update problem?

Alan Sparks asparks at doublesparks.net
Sat Jun 13 01:57:47 CEST 2009


Testing Xymon 4.3 beta2 on CentOS 4.7 (x86_64 and i686) systems.  I've
noticed the updates to RRD files are not synchronized to disk in a
timely manner.  For instance, for a random host, the rrd files list as
follows:

-rw-r--r--  1 hobbit hobbit  38624 Jun 12 17:10 ifstat.eth0.1005.rrd
-rw-r--r--  1 hobbit hobbit  38624 Jun 12 16:50 ifstat.eth0.rrd
-rw-r--r--  1 hobbit hobbit  19640 Jun 12 17:00 la.rrd
-rw-r--r--  1 hobbit hobbit  19640 Jun 12 17:05 memory.actual.rrd
-rw-r--r--  1 hobbit hobbit  19640 Jun 12 17:20 memory.real.rrd
-rw-r--r--  1 hobbit hobbit  19640 Jun 12 17:25 memory.swap.rrd
-rw-r--r--  1 hobbit hobbit 304400 Jun 12 17:40 netstat.rrd

There is a huge disparity in timestamps on these files.  Curiously, if I
refresh the trends page for the host a time or two, the files will
suddenly come up to date.  I assume there is some write caching behavior
in some part of Xymon that is not flushing data until a timeout, or
until (perhaps) something tells it to?

This causes graphs to have some missing data until the user hits
refresh.  Also, we use DRRAW, which will not see timely updates.
Is this a known issue in the beta?

-Alan



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