[LON-CAPA-admin] library server problem

[Bob Gonzales]

Stuart,

Thanks for the quick reply.

It is a DNS problem as you surmised.  The problem is with our campus DNS
servers.  They are acting really flakey.  One won't reply at all to some
queries and the other won't resolve some addresses.

Fortunately, I have a domain server for my subnet that does resolve
everything.  I was about to stop running this server and let our campus
people manage the DNS for our subnet.  I had already removed this dns
server from some of the loncapa server's resolv.conf files which is why
some servers were acting differently from others.  I guess I'll continue
to use my DNS server for now.

Thanks for the help!

Bob Gonzales
Chemistry Dept
Binghamton University


-----Original Message-----
From: lon-capa-admin-bounces at mail.lon-capa.org
[mailto:lon-capa-admin-bounces at mail.lon-capa.org] On Behalf Of Stuart
Raeburn
Sent: Sunday, November 11, 2012 9:41 AM
To: lon-capa-admin at mail.lon-capa.org
Subject: Re: [LON-CAPA-admin] library server problem

Bob,

> My loncapa library server (loncapal1.chem.binghamton.edu) doesn't appear
to
> be working properly.

It looks as though your server is back up (as of 9am EST, 11/11), so
you were evidently able to resolve the issues you had encountered
yesterday.

> Earlier today I applied centos updates to serveral of my access servers,
> not the library server.  It took about 30 minutes for loncontrol to
start
> up when I rebooted them.

Slow start times for loncontrol usually mean that something is amiss
with domain name resolution on your server.

Your lonnet.log shows logging entries spread over several minutes
reporting:
"no IP found" for a number of hostnames for LON-CAPA servers.

Although a handful of these are the usual suspects (i.e., servers for
which IP mapping will always fail because use of the server has been
discontinued), I see at least three for which IP <-> hostname mapping
is definitely available:

homework.phyast.pitt.edu no IP found
naua0.chm.nau.edu no IP found
loncapa.mit.edu no IP found

The issue can occur if DNS service is unavailable.  Checking the
contents of /etc/resolv.conf is a good starting point.

There can also be issues on a specific server (server cannot talk to
itself via the LON-CAPA daemons) if the IP of the server reported by:

/sbin/ifconfig

does not match that retrieved from DNS resolution for the hostname
specified for your server in /home/httpd/lonTabs/hosts.tab

> So, I tried logging directly onto my library server and I get the page
that
> says "This LON-CAPA server is temporarily not available for login".
>  Restarting the httpd and lon daemons takes about 30 minutes here too
and I
> still get that page.

The log messages include several "WARNING: A socket timeout was
detected" followed by "WARNING Shutting down a socket".

I also see a number of instances of:

Attempted insecure connection disallowed
Rejected client 128.226.130.234, closing connection
CRITICAL: Disconnect from 128.226.130.234 (binghamtona7)

which suggests there might either be an issue with reverse DNS, or
that you have other than values of 1 (the default) set for:

PerlSetVar     loncAllowInsecure
PerlSetVar     londAllowInsecure

in /etc/httpd/conf/loncapa.conf

but you do not have certificates signed by the LON-CAPA Certificate
Authority installed.  (See the section: "Internal LON-CAPA SSL" in the
Domain Coordination manual, e.g.,

https://s10.lite.msu.edu/adm/help/Domain_Configuration_SSL.hlp

for more information).


Stuart Raeburn
LON-CAPA Academic Consortium


Quoting Bob Gonzales <rgonzal at binghamton.edu>:

> My loncapa library server (loncapal1.chem.binghamton.edu) doesn't appear
to
> be working properly.
>
> Earlier today I applied centos updates to serveral of my access servers,
> not the library server.  It took about 30 minutes for loncontrol to
start
> up when I rebooted them.  When it did finally finish booting I could log
in
> and get to the roles screen but when I choose a course I get
>
> "The following problems occurred:
> Map not loaded: The file
>
/home/httpd/html/userfiles/binghamton/9N542115927ff4fbcbinghamtona3/defaul
t.sequence
> does not exist."
>
> So, I tried logging directly onto my library server and I get the page
that
> says "This LON-CAPA server is temporarily not available for login".
>  Restarting the httpd and lon daemons takes about 30 minutes here too
and I
> still get that page.  I'm not sure what to check next.  The library
server
> did not get any centos updates applied today.  It was only rebooted.
>
... many log lines removed here ...
>
> I've been down all afternoon and evening so any help would be greatly
> appreciated.
>
> Thanks,
> Bob Gonzales
> Chemistry Dept
> Binghamton University
>

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