Multiple server Nic cards-public and private

I have seen a lot of questions on this subject and I happend to have some graphs handy so I thought I would put up a post that should help all "big" boards understand this a little better.
In a multi server setup the web server needs to talk to 2 different places. The internet so users can come and get their data and the database server to get the information they are requesting. This diagram shows that relationship:


The web server should have 2 seperate NIC cards, one facing the internet and 1 facing the database server. Even if your traffic is not that high trying to do this over 1 nic card is not a good idea because database requests will have to wait for the web requests.
The database server NIC will handle far more traffic than the public NIC. Let's look at some graphs. This graph shows 24 hours on my web server. That would be about 300 users at the low and 2200 simoultaneous users at peak



The blue line represents the amount of data going out to the users, the green line represents the data coming in. Notice that there is far more going out as the web server serves up the pages. The "95th percentile" a measure of how much bandwidth you use is 4.97 mbits or megabits per second so out to the users a 10 based connection would be more than enough.

Here is the same graph between the webserver and the database server:



In this case the blue line, way at the bottom represents the data from the web server to the database server. The green lines are the database server returning data to the web server. Notice how much more data goes over this connection than actually goes out to the users. That is one of the reasons it is so important to have it on a seperate nic card. Also note that the 95th percentile is 38.8 mbit so you would not be able to run a 10 based nic card you need a 100 based to not create a bottleneck. It is not neccesary to run a gigabit card although you would still see some improvement from that as it would let stuff get "off the wire" quicker at peak load.

Hope this helps!

[taydu]

How would I set up four servers to run vbulletin?

2x running Apache
2x running Mysql

- I wanted to be able to manage the 2 mysql server via ssh not thru the apache server.

I did some reading but not quite sure, so I better ask the expert

- So each of my server need dual NIC ?

- The two web server will need dual Gigabits NIC (1 to the internet and one to the DB?)

- The two Mysql serve also need 1 gigbits NIC and 1 100mbps (giga to web server, and 100mbps to the internet for ssh connection?)

- 1x Load balancer for the 2 web server ? (which load load balancer is good)

- 1x gigabits switch to connect two web and 2 mysql servers together ?

thanks guys

[alexi]

You may need another switch to tie the servers together to go out to the internet for management depending on how many ports your host gives you. The load balancer may also be able to do this depending on the number of ports
So you would end up with internet line coming in
switch
Load balancer
web boxes
Database 10/100 cards off that switch

Then in the back end all 4 boxes on 1 switch

I'm not an expert on load balancers but I have heard good things about the Coyote's you might want to have a look

[taydu]

I'm not really good at this, if possible can you demonstrate it using diagram?

What you said about is the Hardware setup, what about the configuration on each box? The reason i'm asking this is because I will not set it up. I will either request the server provider tech to configure it or pay some admin to do the set up so i want to have it clear for them to understand what i'm trying to do.

Thanks

[Marco van Herwaarden]

I strongly suggest you post your question in the Server Configuration forum at vbulletin.com, where Eva2000 (our server configuration expert) might be able to help you a bit more.