I have been using the mirror mechanism for one year for the online T2K /ND280 (neutrino oscillation experiment at J-PARC, Japan).  It has been a savior to allow access to all collaborators to the Elog.  The experiment online computers are all behind a double firewall that allow only communication through ssh and http in one direction: from the inside to the outside. The master Elog is located in Canada and accessible remotely to all collaborators.  The mirror Elog is located inside the firewall on one of the online machines in Japan and synchronization is setup to run automatically every 5 minutes. There are 10 logbooks defined for each of the sub-detector groups.

At first I encountered a big problem when messages were added on both sides.  It turned out that Elog mirroring does not work when the two instances are running on different time zones. After I set the machine in Canada to run on Japan time (JST), no further problems have happened. Postings are routinely entered on either of the Elogs and synchronization works well.  This feature is essential to having a workable Elog for the T2K experiment. 

I had reported the problem of timezones to Stefan last year. He was going to put it on his wish list.

• Stop both elogd servers on each side
  
• Do the rsync
  
• Restart the elogd servers
  

 A couple of comments:

• In principle you could use one elogd.cfg for two running daemons, but only if they do not modify the file. If you use "extensible attributes" for example, you would have write access. If this happens from both servers at the same time, the config file can get corrupt. This is even more true with a password file, which gets written every time a users accesses a page. If you only run one server at a time, then they can share the config file of course.
• The synchronization works bi-directional between two elog daemons. Requirement is that they have access to each other. The synchronization master acts like a "browser" to the slave to send/retrieve entries. So if you can affort punching a hole into your firewall between NET1 and NET2, you could synchronize two servers directly and don't have to bother with three servers. If you have however really physically separated nets, such that you need a memory stick to transport data from one net to the other, then indeed you need the above described scenario. I never tried it in this way, but in principle it should work.

Actually I do want to receive a copy, just to be sure that the emails got sent out correctly. I agree that an option would be good for that but it's not implemented right now. An alternative solution is to define a filter in their email client to discard these messages (like if subject contains ELOG and sender equals your own mail address).

No, but you can remove the "Department" with

Remove on reply = Department

this way the attribute vanishes, but that should be ok since you always have the link to the original entry which contains the department.