[Xymon] Broken custom graphs on trends page

[Ralph Mitchell]

Here's a twist - I just tried it at home on a Gentoo system and
xymon-4.3.7 is happily doing all the graphs for 11 filesystems,
distributed as 3 + 3 + 3 + 2.  When I mouse-over the 2 disk graph, the
url shows "start=10&count=3", so maybe it's a problem with rrdtool? I
know there are other things in between that url and actually getting
the graph, but if rrdtool is told to graph 3 data sources and is only
given 2, it could just be choking.

I don't know what version I have in SLES11 at work, but at home it's
rrdtool-1.4.5-r1.  Maybe this version handles it more gracefully if
there's a data source missing.

Ralph Mitchell


On Thu, Apr 26, 2012 at 7:46 PM, Ralph Mitchell <ralphmitchell at gmail.com> wrote:
> Did you ever get any response on this broken graph issue?  I'm seeing the
> same thing now.
>
> I have a system with 11 file systems. Multi-graph shows them in sets of 3,
> except for the last 2, which don't show at all.  When I view the page
> source, I can see that the link says first=10&count=3. I figure that must be
> breaking the graph generator because there are only 2 more graphs to show.
>
> This is stock 4.3.7, btw.  I'll dig into the code later and see if I can see
> why the math miscounts.
>
> Ralph Mitchell
>
> On Mar 15, 2012 11:14 PM, "Jeremy Laidman" <jlaidman at rebel-it.com.au> wrote:
>>
>> Xymonsters
>>
>> I'm looking for a way forward on the "broken multiple graphs" problem
>> that I'm experiencing.  Excuse the long post; it's part brainstorming,
>> and part context-setting.
>>
>> For a while there have been some discussion on the list about how
>> custom graphs can get displayed incorrectly as if they're multi-graph
>> when they're not.  (I think I'm using the correct term "multi-graph"
>> here.)  Xymon works out that there are enough RRD files to fill more
>> than one graph, and shows several graphs, each with a different
>> "first" parameter.  For me, in many cases all of the lines fit on one
>> graph, and so the other graphs show as a broken image icon.
>>
>> A work-around seems to be to explicitly show "<!-- linecount=N>" to
>> define how many lines should be expected on a set of graphs.  I've
>> done this in my devmon templates to prevent the broken graphs.
>>
>> However, this work-around is only available for custom graphs that
>> create their own status webpage using HTML (in which the "<!--
>> linecount=N>" tag can be included) and send them to Xymon using a
>> "status" message.
>>
>> I have some collectors that send their data to Xymon using "data"
>> messages, because I don't want to grow my Xymon display too wide, with
>> a bunch of dots that can only ever be green.  So my graphs show up in
>> the trends column, which is exactly where I want them.  But because I
>> can't add a "linecount" anywhere, I get broken graphs.
>>
>> I really don't think I'm doing anything out of the ordinary here, and
>> certainly not deviating from the documentation.  I've scoured doco,
>> mailing list, and even code to find out what can be done to work
>> around this problem.  Finally, I've come to the conclusion that the
>> Xymon code is simply unable to work out how many graphs to show in all
>> situations, and its heuristics are not working sometimes.  This is the
>> only bit of my Xymon installation that is tarnishing its reputation
>> here, meaning that it doesn't compare favourably with other products,
>> so I'd really like to get this fixed somehow.  But I'm not sure what
>> to do about it.  If I'm simply doing something wrong, then please let
>> me know, and ignore the rest of this post.
>>
>> So, what am I asking for?  There might be a way to get Xymon to work
>> out the graph linecount more universally, perhaps at the expense of
>> more code complexity, compatibility, CPU cycles or disk I/O (I think
>> the some code comments describe an intent to avoid scanning the
>> directory).  But even so, I think what I'd like to have is a way of
>> overriding the heuristics other than the "linecount" hack.  But what's
>> the best way to do this?  I'm willing to cut code to get this fixed,
>> but my effort should be inline with the future of Xymon, as well as
>> having maximal usefulness to others.  It also needs to not break the
>> existing heuristics used for the standard graphs (disk, inode,
>> if_load, etc).
>>
>> One idea is that I could add a "LINECOUNT" keyword into the graphs.cfg
>> file, something like this:
>>
>>  [bindstats]
>>      TITLE DNS Queries and Responses
>>      YAXIS per second
>>      LINECOUNT 6
>>      ...
>>
>> This would help with both data and status messages that are falling
>> victim to this problem.
>>
>> It also occurs to me that the multi-graph code doesn't seem (to me) to
>> make sense for graph definitions that don't have @RRDIDX@ type indexed
>> filename lookups.  So perhaps the simplest thing would be to assume
>> linecount is zero if FNPATTERN is not specified in the corresponding
>> graph definition.
>>
>> Other ideas?
>>
>> Cheers
>> Jeremy
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