[Server-devel] Possible Jabber Problem on Server

Andrew Berkowitz aberkow at us.ibm.com
Thu May 8 17:15:19 EDT 2008

Or, how do I just wipe out the mnesia database and start over?

Andrew Berkowitz
aberkow at us.ibm.com
NYCBoE: 718-935-5471
cell: 917-613-3941

             York/Contr/IBM at IB                                          To 
             MUS                       wad at laptop.org, martin at laptop.org   
             Sent by:                                                   cc 
             server-devel-boun         server-devel at lists.laptop.org       
             ces at lists.laptop.                                     Subject 
             org                       Re: [Server-devel] Possible Jabber  
                                       Problem on Server                   
             05/08/2008 12:48                                              

To resolve the problem, I am going to uninstall jabber and then reinstall.

When I tried to uninstall ejabberd, rpm complained that ejabberd is needed
by xs-pkgs-0.3.0-1.noarch

I am not familiar with xs-pkgs. Should I assume that this is specific to
the XS server?

Should I also uninstall xs-pkgs and then install it again? Or should I
specify --nodeps?

If I set up jabber to use MySQL rather than the default flat files, will
any XS-specific processes discontinue to work? Do any XS-specific process
use the files directly?

Thank you.

Andrew Berkowitz
2 MetroTech Center, Suite 3900
Brooklyn, NY 11201
aberkowitz at schools.nyc.gov

-----Original Message-----
From: John Watlington [mailto:wad at laptop.org]
Sent: Thursday, May 08, 2008 12:52 AM
To: Martin Langhoff; Berkowitz Andrew (Project Connect)
Cc: John Watlington; server-devel; Kim Quirk
Subject: Re: Possible Jabber Problem on Server

On May 7, 2008, at 10:28 PM, Martin Langhoff wrote:

> On Thu, May 8, 2008 at 2:19 AM, Berkowitz Andrew (Project Connect)
>> Greetings from New York.
> "G'day mate" from New Zealand!
>> Although the short hostname, schoolserver, has stayed the same, the
>> domain has changed from 00b000.nycboe.org to 00b001.nycboe.org and
>> back to 00b000.nycboe.org. When I changed the domain & address, I
>> changed the
> Hmmmm. That's unsupported at the moment. Wad might have more
> experience changing the FQDN...

I've only recovered from that by nuking the ejabberd installation (rpm -e
ejabberd; rm -r /var/lib/ejabberd/; yum install ejabberd)

>> Jabber servers are
>> notoriously finicky and frequently return the nodedown message if a
>> server's hostname changes.
> Exactly, and we haven't yet done the legwork to make sure that this
> works end-to-end.

We've done enough to know that changing the host/domain name is a big
problem with the current presence server.

>> The normal resolution is to export the database, convert it and
>> import it. I tried this conversion using the Erlang conversion
>> utility.
>> I also reimported the original database. Some people report that just
>> exporting and importing, without conversion, fixes the problem.
>> This process
>> also did not resolve the issue.

I found at least one recipe which claimed to fix this problem a while back,
but didn't test it.

> Hm. What happens if you wipe out the mnesia database and start from
> scratch.

Fixes the problem.

>> Also, I have another concern. The jabber database is kept in text
>> files.
>> This configuration is fine for small sites. But with many users, it
>> is better to keep the database in MySQL for better performance and
>> better reliability.
> If I can get mnesia to use PostgreSQL as a backend, I'll do it.

There are configuration file option for ejabberd to use postgreSQL, etc.
for the database. Perhaps some volunteers can play with these ?

>> Another question: You've reported a bug where If an XO is reimaged
>> and then needs to re-register with the server, it cannot. In this
>> case, is it okay to export the database as text, manually delete the
>> entry, and then import the database.

> For a quick fix, you can delete the entries in the SQLite db in
> /home/idmgr . We'll have a UI for this later.

Wrong database. If that bug is due to a database, it is the ejabberd

But if you are referring to #6919, it is harder to replicate than Giannis
at first. I do this all the time, when testing builds/servers, and
hadn't seen it.
It was easier to replicate for a while, when the presence server in the
local area was misconfigured.

> All these ad-hoc DBs need to be under some control, and the UI will
> probably be handled as an extension of Moodle's user mgmt facilities.

Darn right...


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