[mythtv-users] Linux frontend database connection problems - FIXED

Piers Kittel mailing at biased.org
Sun Aug 19 13:44:12 UTC 2007


Thanks *so* much for replying - it is much appreciated!

> Have you started at first principles?

Yeah, but I'll do it again.

> Can you cross ping between the machines?


> Can you ssh from the frontends?  Needs /etc/host entries to be  
> correct.


> Can you nsf mount from the frontends? Needs stuff setup and running on
> the backend machine. If nsf works, then you have proved that all the
> required TCPIP is correct.

Assume you mean NFS - yes, as one of the frontend is a diskless  
frontend, and accesses its data via NFS which is on the backend.

> Now that leaves mysql access.
> Make sure mysqld is OFF on each frontend and running on the backend.

MySQL is not running on the frontends

> Make sure that the mysql ports are open.  Fedora has a little program
> called 'lokkit' which is made for port opening/checking.

MySQL should be working, after all, the OS X frontends doesn't have  
any problems.  I use a program called nmap, and it reports:

piers at hinata:~$ nmap destiny

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2007-08-19 13:13
Interesting ports on destiny (
Not shown: 1670 closed ports
22/tcp   open  ssh
53/tcp   open  domain
80/tcp   open  http
111/tcp  open  rpcbind
443/tcp  open  https
665/tcp  open  unknown
2049/tcp open  nfs
3306/tcp open  mysql
6543/tcp open  mythtv
6544/tcp open  mythtv

Nmap finished: 1 IP address (1 host up) scanned in 0.279 seconds
piers at hinata:~$

As we can see, there's a mysql entry in the list - as well as 2  
MythTV ports.

(FYI, Hinata = the diskless frontend, destiny is the backend)

> The backend needs a unique name/IP. Set it in each frontend in
> /etc/hosts. DHCP is a real problem here: use static IP addresses.

The backend and the diskless frontend both use static IP addresses.

> Mythtv-setup on the backend cannot use !!!

Correct - remember the OS X frontends works fine.

> At this point you should be able to ssh into the back from the fronts
> and vice versa. If you set up nfs then you should be able to mount the
> storage partition from the frontends.

Have done...

piers at hinata:~$ df -h
Filesystem            Size  Used Avail Use% Mounted on
tmpfs                 126M     0  126M   0% /lib/init/rw
tmpfs                 126M     0  126M   0% /dev/shm
rootfs                9.2G  4.2G  4.6G  48% /
                       298G   69G  230G  23% /video
piers at hinata:~$

> Create a mysql user for each frontend machine by amending and re- 
> running
> the mc.sql script which is in mythtv/database.
> ....(I'm not sure if mysql will work from multiple frontends using the
> same mysql user.)

Can't be a problem with the server, because all OS X frontends works  
fine - just not the Linux frontends.  Did this anyway, and didn't work.

> At this point, running 'select host,user,password from user;' on the
> mysqld server (backend) machine, as root mysql user should list the
> various frontend machines by name, the mysql users and show the  
> hash of
> the password. At this point you should be able to log into the mysql
> server from each frontend and run mysql queries as the frontend's user
> and as the root mysql user. If you cannot do this, myth will not be  
> able
> to either.....

I can connect to the mysql database via the frontend using the mysql- 
client software:

piers at hinata:~$ mysql -h -u mythtv -p mythconverg
Enter password:
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 73
Server version: 5.0.32-Debian_7etch1-log Debian etch distribution

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> quit
piers at hinata:~$

It works fine!

> Run 'find' to check for duplicate copies of mysql.txt on each machine.
> Fix the /home/mythtv frontend copy of mysql.txt to refer to the  
> correct
> backend IP addess and the frontend mysql user name.

Have deleted every instance of mysql.txt on the frontend, and re-ran  
the frontend, and entered the exact same settings I used to log onto  
the server above and it doesn't work!  I am much more confident the  
SQL driver mythtv uses is broken somehow.

2007-08-19 13:39:53.323 Writing settings file /home/piers/.mythtv/ 
2007-08-19 13:39:53.338 Unable to connect to database!
2007-08-19 13:39:53.339 No error type from QSqlError?  Strange...
QSqlQuery::exec: database not open
QSqlQuery::exec: database not open
2007-08-19 13:39:53.392 DB Error (KickDatabase):
Query was:
No error type from QSqlError?  Strange...
2007-08-19 13:39:53.448 Failed to init MythContext, exiting.

Hmm... libqt3-mt-mysql somehow got uninstalled (probably in the dist- 
upgrade) - reinstalled it, now mythfrontend works, but very slowly  
and video doesn't work, but that's another thread :)

> And remember:
> If at first you don't succeed, sky-diving is nor recommended.

Good advice.  :)

Thanks for all your help and for your time!  It is much appreciated :)

Regards - Piers

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