Viability of nginx instead of hardware load balancer?

[John Moore]

Barry Abrahamson wrote:
>
> On Sep 15, 2009, at 9:41 AM, John Moore wrote:
>
>> I'm working on a project where it's critical to minimize the 
>> possibility of a single point of failure, and where there will be 
>> quite high traffic. Currently in another version of the system we're 
>> using nginx as a remote proxy server for Tomcat, but the current plan 
>> is to use a hardware load balancer in front of a Tomcat cluster (or a 
>> cluster of nginx+Tomcat instances). I'm wondering, though, given the 
>> extraordinary performance and reliability of nginx, whether we might 
>> be able to omit the hardware load-balancer and use instead a couple 
>> of dedicated minimal nginx servers with failover between them. If 
>> anyone has gone down this path and has some good ideas and/or useful 
>> experience, I'd be keen to hear from them.
>
> We are using nginx as a reverse proxy (load balancer) serving tens of 
> thousands of requests per second across various large sites 
> (WordPress.com, Gravatar.com, etc).  We deploy our nginx reverse 
> proxies in active-active pairs using Wackamole and Spread to control 
> the floating IPs for high availability.  Our busiest load balancers 
> (req/sec) are serving about 7000 req/sec and the most traffic per 
> machine is in the 600Mbit/sec range.  We could push each machine more, 
> they aren't maxed out, but we like to leave some room for growth, DoS 
> attacks, hardware/network failures, etc.  The bottleneck for us seem 
> to be the large number of software interrupts  on the network 
> interfaces cause the boxes to become CPU bound at some point.  I am 
> not sure how to reduce this, it seems like a necessary evil of running 
> something like this in user space.  I have wanted to try FreeBSD 7 to 
> see if it performs better in this area, but haven't had a chance yet 
> (we are running Debian Lenny mostly).
>
> We are using "cheap" commodity hardware.
>
> 2 x Quad-core AMD or Intel CPUs
> 2-4GB of RAM
> Single SATA drive
> 2 x 1000Mbit NICs
>
> Since it is so easy to deploy more servers, it's super easy to scale, 
> and this configuration has been ultra-reliable for us.  Most of the 
> failures we have had are from human error.
>
> Hope this helps,
>
>
It certainly does, thanks! Could I trouble you to explain a little more 
about your use of Wackamole and Spread? I've not used either of them 
before. Also, is there any reason why a hosting company would have 
problems with such a setup (i.e., this won't be running in our hardware 
on our premises, but we have full control of Linux servers).