[chef] High Availability of Bookshelf in Chef 11

[tetsu soh < >]

Hello,

According to document[1] of Chef 11 Server, there is an option in Bookshelf part

bookshelf['ha'] :  Use to run the Chef server in a high availability topology. Default value: false.

What does this mean? Does the HA here mean we can setup a bookshelf cluster with multiple nodes running Bookshelf service and Bookshelf will sync data (replica) automatically for us?
If it is true, how can I specify nodes in the cluster?
If it is false, how can I set up a cluster of Bookshelf ?
Can I use other S3 service instead of Bookshelf ?

Thank you for your help.

Regards,

Tetsu

[1] http://docs.opscode.com/config_rb_chef_server_optional_settings.html