Problem extending the

[Gaspar, Carson]

FIFO limits can and should be queried using pathconf("/path/to/pipe",
_PC_PIPE_BUF) (or fpathconf on an open fd).

-----Original Message-----
From: nagios-devel-bounces at lists.sourceforge.net
[mailto:nagios-devel-bounces at lists.sourceforge.net] On Behalf Of
william(at)elan.net
Sent: Thursday, December 14, 2006 9:35 AM
To: Nicolas COLIN
Cc: nagios-devel at lists.sourceforge.net
Subject: Re: [Nagios-devel] Problem extending the


If you're interested in increasing buffers, here is patch:
  http://www.elan.net/~william/nagios/nagios25-largerbuffers.patch
[warnings about it being experimental and use at your own risk apply]

Regarding 512k FIFO limit, while its good to be safe and I've no
problem with it, it really has been quite some time (over 10 years)
when 512k was stopping factor; unfortunately however what are FIFO
buffers is badly documented on unix systems you likely to use so
doing it above 4k (even above 1k) like Ethan says is just not safe -
do experiments on your own if you like to be adventurous though...
Best I can tell you is that I got 3k plugin output with that patch
on linux rhel3 & linux suse10 systems.

On Thu, 14 Dec 2006, Nicolas COLIN wrote:

>> Ethan Galstad <nagios <at> nagios.org> writes:
>>
>> The problem you'll run into is due to a limitation with FIFOs in
>> general.  The POSIX standard only guarantees an atomic write of 512
>> bytes max to a FIFO, so writing more data than 512 bytes at a time
could
>> land you in trouble.  AFAIK, most OSes bump this level up a bit, but
the
>> max buffer size on a FIFO is often limited to 4K, so your total write
>> size can't really be above that level.
>>
>> Length limitations for plugin output will disappear with Nagios 3.x.
>> There is a new IPC method for handling active host/service checks
that
>> allows for long plugin output (its capped at 4K for safety's sake)
and
>> there is a new external command that will allow passive checks to
have
>> longer (and multiline) output as well.  The new PROCESS_EXTERNAL_FILE
>> command will tell Nagios to read other external commands/passive
checks
>> results from an external (flat) file.  Regular files don't have line
>> length limitations, so this will be a useable workaround.
>>
>> So, your the problem you have will disappear once Nagios 3 is
released,
>> but it will still be a problem for Nagios 1/2.    Hope that helps.
>>
>> Ethan Galstad,
>> Nagios Developer
>> ---
>> Email: nagios <at> nagios.org
>> Website: http://www.nagios.org
>
> Hi,
>
> Thanks for you answer. It helps.
>
> I tried different values but get stuck to low. I am stopping
investigating on
> this issue.
>
> I will impatiently wait for the v3. By any chance, do you have an idea
of the
> release date or even of the first beta date ?
>
> In the mean time, I am thinking of using Nagios with MySQL (instead of
default
> files) which will allow me to update the database directly. Do you
think this
> could be effective ?
>
> Thanks again.

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