I am using Nginx 1.0.5 to reverse proxy to a pool of three upstreams.
One of them is configured as a backup upstream. From time to time, very
rarely, a request will be proxied to the backup upstream when it should
not be. The two normal upstreams are completely healthy, and at
extremely low load.
Why might this be happening?
I see in the documentation
(http://wiki.nginx.org/HttpUpstreamModule#server) that the upstream
module will shunt to backup if the other upstreams are “down or busy.”
What is the definition of “busy” in this context?
Looking in the debug log, I see many many instances of “http upstream
recv(): -1 (11: Resource temporarily unavailable)”. Is this related?
One thing I haven’t tried is to adjust the max_fails parameter, but
perhaps I should.
Posted at Nginx Forum: