Hardware Requirements for RADOS Gateway Cluster

[Brice Burgess <briceburg@gmail.com>]

I am planning the system architecture around a ceph cluster [my first!]. 
While resources for setting up the basic cluster (MON+MDS+OSD) are 
readily available*, I haven't come across anything outlining production 
recommendations for a RADOS Gateway Cluster. Specifically;

1. Is it preferable to run the RADOS Gateway on a MDS machine [for 
latency issues], or should the Gateway run on seperate hosts/VMs than 
the ODS/MON/MDS servers?

2. I've seen reference that multiple RADOS Gateway servers can be setup 
as a cluster "to scale". Is this possible? Is there an 
example/documentation for this? Is it just 2 standalone gateways with a 
load balancer in front?

My assumption is to provision a dedicated machine for the RADOS Gateway. 
I'd treat this machine as a "front end proxy/caching server" meaning it 
would have a lot of RAM for varnish/nginx and a low latency, high 
throughput network connection to the ODS/MDS machines as well as one to 
the public network.

Any thoughts and suggestions are welcome. Eventually I'd like to release 
a whitepaper of this setup if we can hit the budget to actually implement ;)

~ Brice