Ceph

http://ceph.com/docs/master/start/quick-start-preflight/#ceph-node-setup

The use of ssh-copy-id in the above document may not work in some cases. Here's a scenario that demonstrates this:

1. I locked two vpm machines. In this case vpm003 and vpm082.

2. I ssh'ed as ubuntu to vpm003 and vpm082 on two separate windows.

3. I created a user named ceph on vpm082. I plan to install the program ceph on vpm082 from vpm003.

4. I performed the ssh-keygen as specified in this page. I have access from my machine to vpm003 and vpm082. As far as I can tell, there is not an ssh link between vpm003 and vpm082 yet.

5. ssh-copy-id now returns: Permission denied.

What we have here is a chicken-and-egg situation. I am running ssh-copy-id to set up the connection, but the connection does not work because it is not set up yet.

The workaround that I have been using in this case is to cat ~/.ssh/id_rsa.pub on vpm003 and to pick and paste that entry into ~/.ssh/authorized_keys on vpm082. Ssh connections after that work fine.

This problem I can foresee also occurring if I physically am sitting at two machines with no ssh connection established yet. This may be a common situation in the real world.