> Following steps worked for me:-
>
> Suspend the Instance and copy the instance ID from instance details.
>
> Go to command-line and view volume list.
>
> #nova --os-username <user> --os-tenant-name <project> --os-password <password> volume-list
>
> Then run following command to attach volume to instance. Replace ID
> of instance and volume (copy from
> above command output) and device ex.
> /dev/sdc or /dev/vdx
>
> #nova --os-username <user> --os-tenant-name <project> --os-password <password> volume-attach <server-id> <volume-id> <device>
>
> This is most likely problem with
> Hyperviser. Are you using KVM or QEMU
> (Xen)?
>
> NOTE:- If above command gives any
> error you may need to set following
> variables:-
>
> export
> OS_AUTH_URL="http://<keystone-server-ip>:5000/v2.0/"
It's a good idea. I tried to do that but the VM is not yet attached with the volume.
1) I list the ID from instance details.

2) I list the ID from volume.

3) I run following command to attach volume to instance

4) Then, when I watch my volume's state, is not attached:

I think your idea is good, but I have maybe done something wrong.. Have you an idea?
I have similar issue. wondering how to change the type...by default, it's ide even though I set the driver to iscsi in tgt.conf