[listing] Problems you have encountered with multi-server setups
Rather than just list all tweaks and positives, how about a thread to list all the problems big boards have encountered moving to and operating multi-server setups and how they worked around the problem or fixed it ? :)
Example:
on a simple 2 dedicated web + db server setup, a few vB forums had issues where they only had 1 network card installed on web server which connected to both the internet as well as to the db server = not ideal.
Solution was to setup web server with 2x network cards installed, one listening to internet and one connected to db server.
edit: Alex has it illustrated at http://www.vbulletin.org/forum/showthread.php?t=111191
Big boards, when issues and problems have you faced and how did you solve them ? :D Particularly, interested in any network configuration issues you have come across :)
Some simple ones off the top of my head:
1. Multiple webservers not able to make use of file-based datastore (the admincp server will create the correct one but other servers will have an outdated one).
Solution: Use memcache and have a central memcache server (now supported by vB3.5.x). My solution is to use eAccelerator to cache datastore by enabling it in config.sys, and then each time datastore is updated (bitfield rebuilt) I restart eAccelerator using its web interface - this renews the datastore in cache. Works like a charm and reduces internetwork traffic and db query at the same time.
2. Multiple webservers mean that for attachments and uploads they need to go to the one webserver.
Solution: Hack attachment.php so it is always read from the one subdomain from the one server and uploads go to that one server, then change templates and style info to specifically read all images from that one server.
3. Search kills database server.
Solution: Set up a slave search server by replicating just thread, post, forum and user tables using mysql replicatiion, and hacking search.php to read from this slave server instead of the main server. I have also hacked the mod usertools.php for searching ip to read that slave server for ip address searching as well.
Erwin, you are the man.
What would it take for you to publish an official document on this topic? The thought of distributing resources across hardware is highly beneficial for so many people, I just can't believe Jelsoft hasn't placed more attention into this aspect of vBulletin's functions. I am working on a project with scalability in mind and we are a point where the powers at be are avoiding a vBulletin solution for none other than high traffic performance barriers.
Basically, we are looking at offloading images, attachments and .php onto discrete servers and synchronizing the primary db under the same node. However, this will not be sufficient, and so the possibilities of propping each individual forum as indivodual servers has come up. The biggest challenge we face in doing, would be to retain the global functions a single forum offers.
I have already requested information over at vbulletin.com on this matter and have been referred here instead. Since you seem like the resident expert on these matters, would you be willing to help(under wage) to establish such a setup? I am not asking for any special favors(per say) since whatever information fathered in the process could be freely distributed to others. So we would essentially pay you for your time.
I know this should most likely end up in another forum, but since the topic was already opened here I took the path less traveled :)