Global Network Block Device - Red Hat CLUSTER SUITE FOR ENTERPRISE LINUX 4.6 Overview

Global Network Block Device

Figure 1.18. Creating Logical Volumes
7. Global Network Block Device
Global Network Block Device (GNBD) provides block-device access to Red Hat GFS over
TCP/IP. GNBD is similar in concept to NBD; however, GNBD is GFS-specific and tuned solely
for use with GFS. GNBD is useful when the need for more robust technologies — Fibre Channel
or single-initiator SCSI — are not necessary or are cost-prohibitive.
GNBD consists of two major components: a GNBD client and a GNBD server. A GNBD client
runs in a node with GFS and imports a block device exported by a GNBD server. A GNBD
server runs in another node and exports block-level storage from its local storage (either directly
attached storage or SAN storage). Refer to Figure 1.19, "GNBD Overview". Multiple GNBD
clients can access a device exported by a GNBD server, thus making a GNBD suitable for use
by a group of nodes running GFS.
25