GNBD (Global Network Block Device) provides block-level storage access over an Ethernet LAN. GNBD components run as a client in a GFS node and as a server in a GNBD server node. A GNBD server node exports block-level storage from its local storage (either
DRBD is a block device which is designed to build high availability clusters. This is done by mirroring a whole block device via (a dedicated) network. You could see it as a network raid-1.