Yes and no. Gluster uses filesystem storage, and you can use it with OpenNebula’s filesystem datastore drivers, works very well. The no part comes in the fact that OpenNebula is agnostic to the underlying technology, it only sees a folder (where the NFS/Gluster mount is), but will not interact with Gluster directly (for example, use some Gluster features like snapshots, instead those are managed directly from OpenNebula’s drivers).
About migration, as long as you are using a shared datastore (which you will if you want to use Gluster) live migration is supported on KVM (the shared datastore is a requisite from KVM). On LXD there is no live migration support yet because, in the words of LXD’s main developer:
“We do have planned work to get a new API specifically to move containers within the cluster, this could internally be made to trigger CRIU for running containers. Whether we’ll do that part or not, I’m not sure given the current state of CRIU (we pretty much can’t test it since it really can’t migrate a whole lot these days).”
When live migrating there is always a pause, but it is designed to be unnoticed (on KVM for example, it should be around 10ms and peaks should never be bigger than 1s).