> I assume that the frontend is also the murder master?
No, the mupdate master is on another server.
> Other pertinent questions are, "How many connection do you normally get?"
Just now this number of daemons are running:
Imapd/s: 327/458 Pop3d/s: 10/5
Theymay get up to 700 ...
The limit on imapd / imaps in cyrus.conf is 1000 each.
We get 6 - 10 IMAP/POP logins per second.
Ok, counting: 5 connections to the failing backend per second,
10 seconds timeout ... there should be enough free daemons available.
> and "In what way is the backend 'down'?"
Machine down ... crash, not reachable (not just imapd down).
Only one IPv4 address involved.
> The client_timeout sets an alarm that interrupts the connect system
> call. The frontend may try more than once, tho, if the backend has
> more than one address, e.g., IPv4 and IPv6. Are you observing imapd
> and pop3d on the frontend that are waiting more than client_timeout
> to give up? As they fail to connect, clients should log:
>
> connect(server-name) failed: timed out
Yes, it's here: connect(server-name) failed: Connection timed out
Ok, this is exactly 10 seconds (== client_timeout) after the login
message.
> Another possibility is that the clients are poorly behaved, e.g.,
> they are getting an error on SELECT, but don't close the connection
> to the frontend. The client_timeout is just controlling the timeout
> of the connect from the frontend to the backend, not the duration of
> the life of the frontend processes. For imapd, the timeout is 30
> *minutes*.
Oh, well. I will get a "chance" to test this situation again next week
(kernel upgrade on backends).
I'll try with enlarging the maxchild in cyrus.conf and/or decreasing the
client_timeout in imapd.conf.
Thanks for your ideas and help!
- Frank
> > I'm running a simple standard murder environment (v2.3.8 on Linux
> > x86_64)
> > - one frontend, two backends. If one of the two backends is down,
> > then the frontend (and the whole system) becomes unavailable after
> > some
> > minutes:
> >
> > On the frontend imapd's and pop3d's are started till the maximum
> > count (maxchild in cyrus.conf) is reached. It seems that they're still
> > trying to reach the "dead" backend server.
> >
> > Maybe it is a timeout issue - I let the default client_timeout
> > (10 seconds) in imapd.conf. Is this value relevant for this behavior?
--
Email: Frank.Richter@xxxxxxxxxxxxxxxxxx http://www.tu-chemnitz.de/~fri/
Work: Computing Services, Chemnitz University of Technology, Germany
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