@florent
I'm seing the same behaviour as well.
To answer the questions you're asking for:
XO from source (7a187)
XO is connected to three separate pools. Backups work most of the times. But I've started seeing the same error. However, it seems intermitent. And somwhat random. Since it will generate an error from one VM, but not on another on the same host with the same SR etc etc.
can't compute delta OpaqueRef: <ref>
from OpaqueRef:<ref>, fall back to a full
can't connect through NBD, fall back to stream export
Backup fell back to a full
There is an assigned backup-network, and it is the same as the management network. With NBD enabled
XO can access all of the hosts on the management/backup network
IPv4