Hey everyone, hopefully you can give me some direction here. I posted this question on the Ceph lists and received answers form a Ceph point of view, but I was also after some feedback from the XEN / XCP community The Scenario: We have multiple dual XEON servers with 4 x 1Tb hard drives as well as servers with 8, 12 & 16 x 1Tb drives. Our plan is to deploy Openstack with XCP (XEN) as a hypervisor and hopefully utilizing the direct attached storage as OSDs for Ceph. We plan to install a small SSD in each server for the installation of XCP and any server related tasks, ie: Openstack components, Ceph, Monitors and in future MDSs. We will break the storage down into 4Tb OSDs running RAID0, therefore having 1 4 OSDs per server, configuring Ceph replicas of at least 2 3. We will also bond 2 x 1Gbps NICs in each server for a standalone storage LAN segment. We dont plan on expanding this infrastructure much more than this for some time, so we dont want to invest in 10Gbps networking hardware at this time. Here are the questions: (Question 1 is really the only directly XEN related question) 1. Is it possible to install Ceph and Ceph monitors on the XCP (XEN) Dom0 or Hypervisor or would we need to install it on the DomU containing the Openstack components? 2. Is Ceph server aware, or Rack aware so that replicas are not stored on the same server? 3. Are 4Tb OSDs too large? We are attempting to restrict the qty of OSDs per server to minimise system overhead Any other feedback regarding our plan would also be welcomed. Thanks Paul