I had the same error and resolved executing the following steps:
generate the public private keys
ssh-keygen -t dsa -P '' -f ~/.ssh/id_dsa
copy the public key to every host you
will connect TO:
scp ~/.ssh/id_dsa.pub my_user_id@1.2.3.4:~/.ssh/id_dsa.pub
(this should prompt you for a password)
shell into the remote machine
ssh my_user_id@1.2.3.4
authorize the key by adding it to the
list of authorized keys
cat ~/.ssh/id_dsa.pub >> ~/.ssh/authorized_keys
log out of the current shell
exit
test that you can log in with no
password
ssh -i ~/.ssh/id_dsa 1.2.3.4
if this prompts for a password ensure the remote user is the owner of the pub key
http://hortonworks.com/kb/generating-ssh-keys-for-passwordless-login/ ((source))
This is from compute1 to compute2 nodes and from controller to compute2 node.
Also, I had to allow nova user permissions to write:
If you want to change the user owning
this file or directory (folder), you
will have to use the command chown.
For instance, if you run
`sudo chown username: myfolder`
the user owning myfolder will be
username. Then you can execute
`sudo chmod u+w myfolder`
to add the write permission to the
username user.
But if you want to add this user to
the group associated with "myfolder",
you can run
`sudo usermod -a -G groupname username`
and then execute
`sudo chmod g+w myfolder`
to add the write permission to the
group.
http://askubuntu.com/questions/487527/give-specific-user-permission-to-write-to-a-folder-using-w-notation ((source))