Matti

Ok. Thanks for the info. I was actually wondering why ipboard had to know about the php opcode caching. I will definitely look into xcache and nginx, I've been hearing good things about them. Since I'm guessing that 90% of the traffic will be guests just browsing the forums, I think a cache will go a long way. This however, depends on ipboard actually fetching most of its data from the cache, rather than hitting the db. We'll see how that goes during the load testing. If the db becomes a bottleneck, we'll have have to look into master/slave setups but I'd rather not because of the complexity. Sure. What's most important for us is to show that we can help them out if they run into trouble down the line.

Great, I didn't know about the shared-memory option, I have to look into that. Even so, that cache is local to one machine. I think the reason why facebook, digg, wikipedia all use memcached is that it can be distributed over many machines. That gives it great scalability. From what I understand, it's basically a distributed hashmap that can be installed on all your webserver nodes or wherever else you have spare memory in effect giving you a giant virtual memory pool. You're right, that is a good design choice. It makes for a more flexible solution. That's right - IPB only supports one cachetype at once. I found out that today by rummaging through the registry source code. Too bad, I think the combo would be best. If I was planning on running this on a single webserver, I would go for eaccelerator. That would give the opcode caching performance boost along with the shared memory data caching. Since our client is willing to pay for the hardware, I think we'll go with memcached. It gives us more scaleability and reduces waste.

Ok. I haven't used eaccelerator myself but I was under the impression that it is mainly used to store compiled php opcodes so that the pages didn't have recompile on every req, whereas memcached is used to store data that would otherwise be fetched from the db. I'm glad to hear your site is running well though, since you have that much traffic.

Allright, thanks for the info, especially the bit about innodb! So, if I understand you correctly, you're not using mecached or something else to offload the db? Since most users are just browsing the forums as guests, I thought that a fat cache would be the key to get good performance. matti

Do you know if this is ipboard specific? Some of the largest sites on the net run mysql so I assumed it would scale just fine.

I assumed that we would run memcached on the webservers. Memcached is memory bound, apache is cpu-bound, so it should be a good fit. You have lots of traffic, your at once record is almost 30k! Good job! What machines do you run your site on? Have you done any special configuration? Thanks. matti

Thanks for the links, they will be useful when persuading the client to go for IPB! The nvidia site is really snappy, but only ~300 users online right now so I'll check back later today when the US wakes up.

Hello! I have a large client that wants to build a forum for its customers. I have recommended IPB, but I haven't used it for anything until now - so I'm a real newbie! The client wants us to plan for 25000 simultaneous users. Not specified how many logged users in or not - let's suppose 5000 logged in. I'm sure 25000 sounds like a lot but considering the size of the client, I can understand the worry. Do you think this is doable with IPB? How would you go about doing this? I'm thinking 2-3 load balanced webservers running memcached and eaccelerator. The dabase server would need to have alot of memory and many CPU cores. For searching, we would use sphinx. Where should this run? On the database-server? any tips & ideas are welcome! matti