Yes, you NEED the -c option. The qmail concurency limits are for OUTGOING
mail (either local or remote). The tcpserver -c option set concurrency
for INCOMING TCP connections which is where you are having the
problem..... The default is 40, I would try 80 or 100 and see what
happens.
On Thu, 18 Feb 1999, Jere Cassidy wrote:
> Mark,
> We removed the -c options because we are currently using
> qmail/control/concurrencyremote and qmail/control/concurrencylocal. should we also
> add -c options to tcpserver?
>
> I know that the backlog _is_ an issue. Our performance increased so much when we did
> -b30 instead of letting the default take over (5). Every time we have upped this
> number, we get performance gains. The problem is that if only one server is left in
> the Alteon's rotation, it seems to get more than 128 connections in a matter of
> minutes. These then seem to have a logarythmic effect. The more connections queue
> up, the more connections are delayed, the more connections are queued up... etc...
> This leads to the 700 number (which i do admit is extermely high-- netstat showed
> some 590 smtp connects). During the slow time this morning after i got all 3 servers
> handling mail, we had about 24 connections total (not just smtp).
>
> Now that i think about it... it seems if the connections eclispse approximately 200,
> we start to have incredible delay on the smtp connects. (this leads me to believe
> that 128 limit mentioned in Redhat Linux 5.2's `man listen` might be our problem). I
> am unsure what to do next.... is there a way to up this limit (besides hacking the
> kernel somewhere)? Do other unices perform better in this area? Doesn't anyone else
> have this problem ?
>
> The alteon takes out servers that are not responsive to its SMTP and/or POP3
> connects.
> It would be difficult to take it out at this point. It has helped us immensely in
> system availability, but I truly believe that our main server (an alpha633) would be
> able to handle _all_ the load if it didnt run into these tcpserver/max connection
> issues.
> Thanks again for the help Mark and anyone else who wishes to contribute!
>
> -Jere
>
>
> Mark Delany wrote:
>
> > >Yes, 700 connections seems high, but after some period of down time, it seems to
> >
> > Just to emphasize what I was saying. I reckon for 30K users (was that the
> > number-ish?), 700 is far higher than normal. I know there is no such thing
> > as normal, but...
> >
> > > tcpserver -l$hostvalue -q -b100 -H -R -D 0 pop-3
> > > tcpserver -l$hostvalue -q -b50 -H -R -D 0 2001
> > > tcpserver -l$hostvalue -t8 -q -b5000 -D -u502 -g2108
> > > tcpserver -l$hostvalue -t8 -q -b50 -D -u502 -g2108
> >
> > In all cases, change the -b to a -c
> >
> > >After reading "man listen" I am reminded of the help this list gave us when we
> > >had this problem before. Our connections were being artificially limited by
> > >Linux to 5 at a time! This was solved with adding the -b20 (then later upping
> >
> > It *may* be worth upping it beyond the default, but the listen queue really
> > only comes into effect if tcpserver isn't keeping up with the inbound
> > connection rate.
> >
> > As long as tcpserver is doing the accept and passoff to qmail-smtpd in
> > enough time, the backlog doesn't apply. the concurrency with -c does of course.
> >
> > >If one server reaches this limit, it is overloaded and if lucky it is dropped
> > >out of the rotation by the alteon. This causes the other servers to overload
> > >and reach the same state.
> >
> > Is the alteon configured to load balance of switch on no response?
> >
> > Also, is it possible to bypass the Alteon for a while? There may be some
> > unknown interaction there.
> >
> > Regards.
>
> --
> ------------------------------------------------------------------------
> // Jere Cassidy - System Administration - D&E SuperNet
> email: [EMAIL PROTECTED] phone: (717)738-7054
> web: http://www.desupernet.net/jere
> pager/pcs: [EMAIL PROTECTED] - (717)203-0042
> ~~~ "While sowing the seeds of Utopia,
> you invoked a convenient amnesia" -BR ~~~
> ------------------------------------------------------------------------
>
>
>
---------------------------------
Timothy L. Mayo mailto:[EMAIL PROTECTED]
Senior Systems Manager
localconnect(sm)
http://www.localconnect.net/
The National Business Network Inc. http://www.nb.net/
One Monroeville Center, Suite 850
Monroeville, PA 15146
(412) 810-8888 Phone
(412) 810-8886 Fax
