If you just want clustered virtual machines, check out Ganeti[0]. It's not advertised much, but this piece of software hosts most of Googles internal infrastruc

If you just want clustered virtual machines, check out Ganeti[0]. It's not advertised much, but this piece of software hosts most of Googles internal infrastructure (not public facing stuff). Unlike Openstack, it has a proper scheduler, and lets you rebalance VMs across hypervisors efficiently. Also unlike Openstack, it can restart VMs if it (or the hypervisor) dies, if you've enabled that. And completely orthogonal to Openstack, it has very strong consistency guarantees. It's not made to start 1000s of VMs in seconds, since each master node has to agree on all decisions, and each operation typically "locks" the involved hypervisor. On the other hand, I haven't been able to break it once in over six years. Note that it really just exposes an API and comes with a superb command-line client. Some assembly required. Source: deployed Ganeti with great success at a billion-euro company, moved on to promising "cloud" project which insisted on using Openstack and promptly quit after a year of fighting obscure bugs (and naive colleagues who did not want to try anything else :)). (If you'd like help deploying it, I'm available!) [0] http://www.ganeti.org/ http://www.ganeti.org/