Need advice for growing site.

info_hash

What is bottleneck? I/O? how is your ram usage in your current setup? how big is your database, do all indexes and often accessed data can stay in RAM?

I'd recommend to start with a good dedi, like 2 HDD in RAID1, maybe also some SSD for the database? 16 GB RAM and an E3. You can find that pretty cheap. Then you will know the hardware you can really use and the hardware your app really need, something you have no way to know with your current OpenVZ VPS. You'll then find what the bottleneck is.

If you need to scale you'll be able to host the database on another server and scale from that. Like two database server + 1 front end server etc.

HA in mind (or at least two front nodes in round robin and a backup database server) in case your service becomes really popular and you want a no downtime solution...

Good luck

AdamM

@Moonshot

I am also a tomcat user on LET, so here are a few thoughts

•Concurrent connections were dropped many times

Which http connector are you using? I get best concurrent connections when I use the NIO connector. But since you use nginx in front, maybe bio would be better, I don't know that setup?

VPS configured with 8GB

That is a nice sized vps! My guess is that most of the ram is going to the JVM running tomcat. And I imagine that ehCache is also within that same JVM. That being said, the heap size is likely multiple GB. The JVM often runs into a problem with multi- GB heaps, as the garbage collection "stops the world"- as they say. This could easily lead to dropped connections. Do you noticed dropped connections aligning with GC times? If so, pehaps find a way to tune he GC. Or, look into he Azul JVM, which attempts to solve that issue. If you think this is the issue, PM me and we can brainstorm.

Finally, Congrats on what sound like a growing web app!