Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Let's say I'm using Amazon's EC2 load balancer. I have it hooked up to two instances (excuse me if my terminology isn't correct). What happens if the load balancer fails? Do both instances fail to work now?

share|improve this question
Stuff explodes. – Josh K May 6 '10 at 4:32
Quis custodiet ipsos custodes? – sampablokuper Dec 2 '10 at 4:50
up vote 11 down vote accepted

Typically load balancers are clustered together into a high-availability pair.

If one load balancer fails, the secondary picks up the failure and becomes active. They have a heartbeat link between them that monitors status.

If all load balancers fail (or are accidentally misconfigured), servers down-stream are knocked offline until the problem is resolved, or you manually route around them.

share|improve this answer
+1 I bet in general: Misconfiguration > Hardware + Software Failure – Kyle Brandt May 6 '10 at 12:19

Yes if the load balancer instances both fail the service is essentially dead. Note that amazons uptime includes up to 4 hours of downtime a year (99.95%)

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.