We want to set up a small cluster, witch will store some databases and testing services at first. The cluster will initially launched on 8 dedicated servers (HP G3/G5). 6 of the servers in in the same rack, and two of them is on individual separate locations. Outside this cluster we have 2-4 powerfull servers that mostly is not using all of their own resources. This got me thinking that these could be added to the cluster and perform cluster operations when they are not using 100% of it's resources. Another feature I want the cluster to have is to run docker containers as cluster services and of course that the cluster is HA and load balanced. I've been searching a lot on this subject, but can't really find a good answer.
The option that is strongest now is to install Ubuntu 14.04 and Apache Mesos and add in the non-dedicated servers as slaves in the cluster after Mesos have implemented dynamic slave attributes