Jens Frank wrote:
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.
Simple but wrong maths, though.
The key is that the "availability" we're talking about is a function
of what a given machine is doing. Individual webservers are likely to
become unusable for many reasons -- apache problems, unbalanced
traffic, etc. But the loadbalancer is nearly bulletproof.. and
shields the user from failures of individual webservers in the
cluster!
--Jimbo