[syslog-ng] Debugging tools for syslog-ng

[Balazs Scheidler]

----- Original message -----
> > > > If flow-control is in use and one of the destinations cannot accept
> the
> > > messages, the other destinations do not receive any messages either,
> > > because syslog-ng stops reading the source.

I misunderstood what you wrote here. The docs is correct. For a single source, throttling the source side means that neither destinations receive messages.

> 
> > this is not true. syslog-ng stops sources individually when their
> > window
> is full.
> 
> But it's a quote from
> http://www.balabit.com/sites/default/files/documents/syslog-ng-ose-3.3-guides/syslog-ng-ose-v3.3-guide-admin-en.html/index.html-single.html#id555527
> 
> 
> 
> On Mon, Nov 5, 2012 at 9:34 AM, Balazs Scheidler <bazsi77 at gmail.com>
> wrote:
> 
> > **
> > 
> > ----- Original message -----
> > > Thanks for your reply
> > > How can I understand when it's enough to increase things? Is there
> > > any manual way to get current values of each buffer, etc?
> > 
> > well, I tend to use loggen for performance tests, also you can query
> > syslog-ng internal statistics using 'syslog-ng-ctl stats'
> > 
> > > Also since I'm logging a lot of things I'd love to know if there are
> > some
> > > other ways to lose messages without seeing them in "dropped"?
> > 
> > syslog-ng counts everything it dropped using the dropped counters for
> > destinations (which is a log-fifo overflow btw)
> > 
> > messages can be lost outside syslog-ng because of transport reasons:
> > * udp shouldn't be used for anything serious.
> > * connection breaks can cause message loss
> > 
> > 
> > > 
> > > > In general, performance wise you want to increase stuff
> > > > (log-fetch-limit,
> > > log-iw-size, flush-lines for file destinations), memory-use and
> > > reliability wise you want to decrease them.
> > > > Also, you have to make sure that sum(log-iw-size) < log-fifo-size.
> > > So you propose just randomly tune those params? I just don't
> > > understand how should I get check if it helped.
> > 
> > no :) random tuning would be slow to converge to the ideal values.
> > 
> > 
> > 
> > I need to see the current state of
> > > each buffer(to be able to get some statistics data) to see if it
> > > helps.
> > 
> > syslog-ng-ctl stats displays the current values of statistics as a csv
> > file.
> > 
> > also you can ask syslog-ng to measure more stats by increasing
> > stats-level (at the cost of some performance)
> > 
> > > 
> > > And one more specific question:
> > > > If flow-control is in use and one of the destinations cannot accept
> > the
> > > messages, the other destinations do not receive any messages either,
> > > because syslog-ng stops reading the source.
> > 
> > this is not true. syslog-ng stops sources individually when their
> > window is full.
> > 
> > > Why there is no messages about it in syslog-ng logs? It must be
> > > error, don't you think so?
> > > And what if I don't have flow-control enabled?
> > 
> > 
> 
> 
> -- 
> Best regards,
> Koldaev Anton

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