On Sat, Nov 01, 2003 at 03:56:37PM +0100, Lars Aronsson wrote:
Jens Frank wrote:
Clustering two web servers will increase the web servers availability to 99%. But now the system has three components: Load balancer (90%), Web servers (99%), database (90%). That's a total availability of 80.19%.
Jens, have you ever seen a real load balancer that had as little as 90% availability, or are you just dreaming up some numbers that will prove your prejudice?
Please try reading the entire mail. It says:
(It's higher, of course, but numbers will become too ugly for this example)
I took the number "90%" as an example. You can make it 99% if you like, the result remains the same: One loadbalancer in front of two webservers reduces availability. Simple maths.
I also think that load balancing a farm of web servers is the way to go, I just want to point out that availability will not increase.
Regards,
JeLuF