Thanks Willy. On the same note you said not to run anything on the same machine, to lower costs I want to run other things on the haproxy front-end load balancer.
What are the critical things to watch for on the server so I can be notified at what point having 2 things on the server are becoming a problem? On Wed, Dec 5, 2012 at 2:00 AM, Willy Tarreau <[email protected]> wrote: > On Tue, Dec 04, 2012 at 02:19:30PM -0500, S Ahmed wrote: > > Hi, > > > > So 500 Mbits is 1/2 usage of a 1 Gbps port (haproxy and the back-end > > servers will have 1 Gbps connections). > > No, the traffic goes in opposite directions and the link is full duplex, > so you can effectively have 1 Gbps in and 1 Gbps out at the same time. > > > How does latency change things? e.g. what if it takes 90% clients 1 > second > > to send the 20K file, while some may take 1-3 seconds. > > it's easy, you said you were counting on 1500 req/s : > > - 90% of 1500 req/s = 1350 req/s > - 10% of 1500 req/s = 150 req/s > > 1350 req/s are present for one second => 1350 concurrent requests. > 150 req/s are present for 3 seconds => 450 concurrent requests. > => you have a total of 1800 concurrent requests (with one connection > each, it's 1800 concurrent connections). > > What we can say with such numbers : > - 1500 connections/s is light, even if conntrack is loaded and correctly > tuned, you won't notice (we're doing twice this on a 500 Mbps Geode > running on 1 watt). > > - 1800 concurrent connections is light too, multiply that by 16 kB, it's > 30MB of RAM for the kernel-side sockets, and twice that at most for > haproxy, so less than 100 MB of RAM. > > - 250 Mbps in both directions should not be an issue either, even my > pc-card realtek NIC does it on my 8-years old pentium-M. > > At only 1800 concurrent connections, the latency will probably be mostly > related to the NIC's interrupt rate. But we're speaking about hundreds of > microseconds here. > > If you're concerned about latency, use a correct NIC, don't run any other > software on the machine, and obviously don't run this in a VM ! > > Hoping this helps, > Willy > >
