Major problem with replication

[Pär Iwarson]

My experience with replication is not the greatest but there is no problem setting up the replication and it works fine for almost a week but then something happens and the replication crashes for some reason. It has been the same way now twice. When I run "SHOW SLAVE STATUS" it appears that the Master_host value is no longer the host of the master. Instead it's shows a part of a query :-/

The error log tells me that the "Error no 13" is involved and I know that is a permission error. But I have given mysql all permissions in the folders and I can't see how I can give mysql any more permissions.

This is what the error log looks like:
------Start Error Log-------------------------------------------------
050126 17:01:14 Could not use ensim-relay-bin for logging (error 13). Turning logging off for the whole duration of the MySQL server process. To turn it on again: fix the cause, shutdown the MySQL server and restart it.
mysqld got signal 11;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
We will try our best to scrape up some info that will hopefully help diagnose
the problem, but since we have already crashed, something is definitely wrong
and this may fail.

key_buffer_size=8388600
read_buffer_size=131072
max_used_connections=2
max_connections=100
threads_connected=0
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_connections = 225791 K
bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

thd=0x87a26a8
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
Cannot determine thread, fp=0xbfe7f608, backtrace may not be correct.
Stack range sanity check OK, backtrace follows:
0x8072614
0x826ac98
0x8296c73
0x824f2bc
0x824f24a
0x80ed158
0x80ee5d7
0x826844c
0x829df0a
New value of fp=(nil) failed sanity check, terminating stack trace!
Please read http://www.mysql.com/doc/en/Using_stack_trace.html and follow instructions on how to resolve the stack trace. Resolved
stack trace is much more helpful in diagnosing the problem, so please do
resolve it
Trying to get some variables.
Some pointers may be invalid and cause the dump to abort...
thd->query at (nil) is invalid pointer
thd->thread_id=1
The manual page at http://www.mysql.com/doc/en/Crashing.html contains
information that should help you find out what is causing the crash.
050126 17:01:14 Error in Log_event::read_log_event(): 'Event too big', data_len: 894259791, event_type: 32
050126 17:01:14 Error reading relay log event: slave SQL thread aborted because of I/O error
050126 17:01:14 Slave: Could not parse relay log event entry. The possible reasons are: the master's binary log is corrupted (you can check this by running 'mysqlbinlog' on the binary log), the slave's relay log is corrupted (you can check this by running 'mysqlbinlog' on the relay log), a network problem, or a bug in the master's or slave's MySQL code. If you want to check the master's binary log or slave's relay log, you will be able to know their names by issuing 'SHOW SLAVE STATUS' on this slave. Error_code: 0
050126 17:01:14 Error running query, slave SQL thread aborted. Fix the problem, and restart the slave SQL thread with "SLAVE START". We stopped at log 'freebsds-bin.002' position 1073149878

Number of processes running now: 0
050126 17:01:14 mysqld restarted
050126 17:01:14 Warning: Asked for 196608 thread stack, but got 126976
050126 17:01:15 InnoDB: Started
050126 17:01:15 Could not use ensim-relay-bin for logging (error 13). Turning logging off for the whole duration of the MySQL server process. To turn it on again: fix the cause, shutdown the MySQL server and restart it.
050126 17:01:15 Failed in open_log() called from init_relay_log_info()
050126 17:01:15 Failed to initialize the master info structure
/usr/sbin/mysqld: ready for connections.
Version: '4.0.21-standard' socket: '/home/virtual/FILESYSTEMTEMPLATE/.mysqlsock/mysql.sock' port: 3306 Official MySQL RPM
------End Error Log--------------------

This is what Master_host looks like:
+--------------------------------+
| Master_Host |
+--------------------------------+-
| 96, 0, 'Robin Marriott')/􏻎􏻷A
|
+--------------------------------+-

There is nothing in "Last_error".

I am clueless and have no idea why this error reoccures after almost a week. I would be very greatful if someone has any ideas why we have this problem.

Both the Master and the Slave is running MySQL 4.0.21 with Linux.