supporting pop-before-smtp

All,

We are using qmail-ldap on 4 nodes with a large NFS-Filer with
takeover capabilities. We are actually only using qmail for SMTP
services, courier is providing POP & IMAP functionality.

Everything in our setup is redundant or has fail over capabilities
with the exception of pop-before-smtp. We are using the
pop-before-smtp daemon (perl) to generate the smtp cdb file.
My setup looks like this:

server1->courier->syslog-ng -> /mnt/filer/maillog
server2->courier->syslog-ng -> /mnt/filer/maillog
server3->courier->syslog-ng -> /mnt/filer/maillog
server4->courier->syslog-ng -> /mnt/filer/maillog

This ran well for a time, but load was corrupting the maillog where
entries would be written inside each other (not one per line). This
would happen say 15 times an hour.

I adjusted my syslog-ng.conf and added.

OS is freeBSD 7.2 and all the NFS locking stuff is on.

destination maillogalt{ file("/mnt/na1/log/maillog" fsync(yes) ); };

This definitely lowered the corruption to maybe twice an hour, but
there is still corruption.

Also pop-before-smtp is writing the cdb file to nfs space. Qmail logs
periodically show a stale file handle. This happens because qmail-smtp
is trying to read this file as pop-before-smtp is writing it.

tcpserver -H -v -URl $ME -x/mnt/filer/etc/tcp.smtp.cdb

Also I cant find documentation on how to use tcprulescheck.. It never
produces any output, (strings shows plenty of rules)

[root@nymail1 ~]# tcprulescheck /var/qmail-smtpd.cdb
rule :
allow connection

The only person I found with a solution for this exact problem was this.

http://www.tnpi.net/internet/mail/toaster/patches/tcpserver-mysql.shtml

Mysql has its own set of problems, and unless I do active active mysql
we just have a mysql single point of failure.

So does anyone have any suggestions/tips for high volume/multinode
pop-before-smtp? (I know I don't want to support it either but such is
life)

Thank you,