LogFAQs > #954894192

Tyranthraxus posted...

I don't work with the guys that manage it so I don't have all the technical details but the load balancer is not a router. Routers serve up a specific machine based on the address you ask it for. The load balancer looks at your request and determines which server to send your request to based on the rules it's given. For example "round robin" just sends every request to a different server, or "sticky sessions" which sends requests from the same client to the same server regardless of load which is necessary for web sessions that have things in session memory.

This is also how you patch webservers and update websites without bringing everything down. Tell the load balancer to send all requests to server A, patch & reboot server B, tell the load balancer to send all requests to server B, patch and reboot server A, tell the load balancer to send to both servers.

Log wise our webservers document all requests as if they're coming from a private IP address but they're actually coming from the load balancer. The client IP address is in the load balancer and through some voodoo magic it knows how to send a response from a specific webserver back to the client that requested it. There's some additional voodoo magic applied by our cto that tracks the real client IP address in a custom field in our logging but I don't know anything about that.

That's interesting, thank you for some inside details! I have not worked with a load balancer yet but it is in my future, I appreciate the insight.

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Ohhh.
I don't know what to do. About this dream and you. I hope this dream comes true.