Re: {bb} Weird problem with SMTP checking

[Philip Clark <bblist@cannae.uklinux.net>]

On Tue, 2005-08-16 at 10:35, Dirk H. Schulz wrote:
> Hi folks,
> 
> I am running BB 1.9h on a debian sarge stable system and have a 
> phenomenon I cannot solve:
> 
> The BBNET host checks a lot of SMTP services on different hosts. For 
> some hosts BBDISPLAY shows a red dot with "SMTP down" every 30 to 120 
> minutes with a duration of around 5 minutes (4:20 to 5.30). Sometimes 
> (once every few days) the uptime duration is several hours, and very 
> seldom the downtime duration is several times these 5 minutes.
> 
> The weird thing is:
> 
> - these smtp services are not down, the successfull connection attempts 
> of bbnet are in their logs

But connection is not necessarily enough for a success.

> - the duration of the downtimes is always around BBNETs BBSLEEP value,
>    that means: if BBSLEEP=300, the downtime is around 5 minutes,
>    if BBSLEEP=150, the downtime is around 2.5 minutes

That is to be expected. If BBNET is testing every 5 mins., BB cannot
record it as being in error for less than that.

> - this happens only to smtp hosts which are way outside of the subnet of 
> BBNET (other colocation center with other internet uplinks), but there 
> is no connection problem:

This could be a coincidence.

>    ping times are always below 10 ms in average, so half of BBNETs 
> accumulated connection attempt times.
> 
> I did not find anything that gives me any hint on where to look. I think 
> I have checked everything with the SMTP Services (postfix) as well as 
> BB, but to no avail.
> And, yes, the bb-hosts file is identical on BBNET/BBDISPLAY and the smpt 
> hosts (they are also BB clients for checking local values).
> 
> Please help me finding what I overlook.
> 
> Dirk

My guess would be that the SMTP hosts are throttling, rejecting
new connections due to processor load spikes. You should be
able to confirm this by looking at the numeric code that the
SMTP server passes back to BB. Just look at one of those red
alert pages.

Cheers, Phil.



-- 
Entropy isn't what it used to be.

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