Hello, As far as I understand, the communication between a VM, running on a node, and a volume, 'running' on another node, is carried out bu open-iscsi (ISCSI client running on the node where you run the VM) and tgt (iSCSI server running on the node where you host the volumes).
Cinder's daemons, in particular cinder-volume, just issue commands for tgt to create volumes and making them available on the network. After that, when you connect a volume to a VM, very likely the Hypervisor is instructed to retrieve the volume through the iSCSI client. Anyway, I found out that: -- the node that host the storage MUST run both tgt and cinder-volume -- cinder-scheduler and cinder-api can be deployed on any other node -- any compute node MUST run open-iscsi (iSCSI, client) in order to access volumes Hope it helps, Marco. On Wed, Dec 5, 2012 at 10:53 AM, Skible OpenStack < skible.openst...@gmail.com> wrote: > Hello everyone, > > I have cinder installed on my controller node, can anyone explain to me > how a VM becomes aware of the volume ? > > After all a VM is launched on a node different than the controller one so > if the VM wants to store something on the Volume, does it have to send the > data to the controller node which in his turn will save the data on the > volume using cinder or is there a direct connection between the VM and the > volume after allocation, if yes, is this connection on the hypervisor level > or what level exaclty? > > Thanks, really appreciate it if you can help me out there ! > > Best regards > Fellow Stacker > > ______________________________**_________________ > Mailing list: > https://launchpad.net/~**openstack<https://launchpad.net/~openstack> > Post to : openstack@lists.launchpad.net > Unsubscribe : > https://launchpad.net/~**openstack<https://launchpad.net/~openstack> > More help : > https://help.launchpad.net/**ListHelp<https://help.launchpad.net/ListHelp> >
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