Ubuntu: Ubuntu MAAS and openstack physical machines and storage node protection


Good day, I was wondering if there is a diagram or document that clarifies for a newbie the physical requirements for an Ubuntu Openstack deployment.

See, all documents I read talk about role separation, but, (at least for me), fail to clarify if they are talking about VMs with roles, or if they talk about physical servers.

We are aiming at running 50 VMs, sharing about 30TB of storage from commodity hardware (web servers, an email, blogs,student registration system).

  1. In a deployment with Ubuntu+MAAS, how many physical nodes do we need?

  2. What roles or VMs are run on each physical node?

  3. We have 3 physical servers with 10 x 1TB SAS drives each. Those will be the storage nodes. Shall we run hardware RAID 10 on those or does openstack/modules takes care of the data protection?

  4. Can we run Cinder+CEPH on Ubuntu MAAS? if we can...do we still need hardware raid on the nodes?

  5. Compute nodes have lots of RAM/CPU cores. Do we need two hard disks on the servers? We have another 3 physical servers for that.

  6. There is something called a "foundation" node. Do they talk about the physical servers that run the whole Openstack+modules thing? Do they run VMs on it? We have another 2 nodes for that purpose in case they are needed.

I guess that coming from the server/san approach makes a little difficult to understand some used-to terms that seems to be left out of the docs.

The most obvious thing is to run hardware RAID (mdadm) on the storage nodes but I get confused when I read that CEPH does erasure encoding plus data replication to other nodes.

How much USABLE space are we getting? Any formula?

Note: we ARE getting trained on Openstack, but my questions are ahead of the beginning of the training.

Thanks for your time and guidance. (edited for easy reading)


From the OpenStack official documentation:

To get the most out of your hardware, it is essential that every disk used in OpenStack Object Storage is configured as a standalone, individual RAID 0 disk; in the case of 6 disks, you would have six RAID 0s or one JBOD. Some RAID controllers do not support JBOD or do not support battery backed cache with JBOD. To ensure the integrity of your data, you must ensure that the individual drive caches are disabled and the battery backed cache in your RAID card is configured and used. Failure to configure the controller properly in this case puts data at risk in the case of sudden loss of power.

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