[Mimedefang] interesting problem with SQL backend

[alan premselaar]

Today I had an interesting situation.

This is more of an FYI in case anyone else has run into similar 
problems. (cross-posted to MIMEDefang list as well)

I use SpamAssassin with MIMEDefang.

I got notified by one of my users that they were unable to send mail 
suddenly.  after checking the logs I determined that MIMEDefang was 
timing out and returning errors.  the cause for this was very unclear 
(which is why i'm sharing my findings with all of you)...

After digging around (and some assistance from David Skoll on the 
MIMEDefang list) I was able to determine that the problem was caused by 
SpamAssassin not being able to connect to the database server where the 
bayes database is stored. (using MySQL on a remote host)

this caused all sorts of "weirdness for no apparently good reason" and 
was initially very confusing to diagnose.

The symptoms were:

* mimedefang started to return "busy timeout" errors.
* when restarting MIMEDefang (with embedded perl enabled) the 
multiplexor wouldn't complete loading and mimedefang wouldn't create the 
socket, causing sendmail to spit out "file 
/path/to/mimedefang/socket/file unsafe" errors.
* turning off embedded perl would allow mimedefang to start and create 
the socket, but then would spawn multiple instances of mimedefang.pl 
which just hung.
* mimedefang.pl -test and/or mimedefang.pl -features would hang 
indefinitely with no output.


the workaround:

   after determining the problem to be the connection to the SQL server, 
simply setting "use_bayes 0" in sa-mimedefang.cf and restarting 
mimedefang resolved the problem. however, this obviously didn't utilize 
the bayes facilities.


the questions:

  I understand that the SQL code for SA is still 'experimental'.  is 
there any way currently to set a forced timeout to connect to the SQL 
server?

is this something I should open a BZ ticket about?

being that I'm definitely not an SQL guru, does anyone have any 
suggestions for configuring a high-availability MySQL server 
configuration that could failover to a backup server should the primary 
one become incapacitated by a low-level hard drive failure?

Currently I have 1 MySQL database server with the bayes databases on it 
(among other databases) and my primary and secondary mail servers both 
make connections to it to check the bayes database.

This may be somewhat specific to the MIMEDefang implentation, but I 
suspect that there is a possibility that this type of behavior could 
have negative impact in other types of SA implementations as well.
again, this is mostly an FYI, but any suggestions are welcome.

Thanks,

Alan