Running multiple Tor instances with the same private key will not provide reliable load balancing as normally only one instance descriptor is listed in the Tor hidden service DHT at a time.

However I've created a tool named OnionBalance which allows Tor hidden services to be load balanced at the Tor protocol level. By working at the Tor level hidden service requested can be distributed between up to 60 back end Tor instances while removing single points of failure.

Using a traditional load balancer like HAProxy behind a Tor hidden service will be limited be the rate of traffic through the single core Tor process.

OnionBalance is now available in the Debian Jessie backports repository so it should be easy to get started with.

Running multiple Tor instances with the same private key will not provide reliable load balancing as normally only one instance descriptor is listed in the Tor hidden service DHT at a time.

However I've created a tool named OnionBalance which allows Tor hidden services to be load balanced at the Tor protocol level. By working at the Tor level, hidden service requests can be distributed between up to 60 back end Tor instances while removing single points of failure.

OnionBalance works analogously to round-robin DNS for Tor where OnionBalance is updates the A records. However the actual implementation is quite Tor protocol specific. The DNS system is not involved at all.

Multiple instances of OnionBalance with the same configuration and keys can be run simultaneously. By running instances in separate physical locations you can have fully redundant Tor onion service hosting.

Using a traditional load balancer like HAProxy behind a Tor hidden service will be limited by the rate of traffic through the single core Tor process.

OnionBalance is now available in the Debian Jessie backports repository so it should be easy to get started with.