Global Network Block Device - Red Hat CLUSTER SUITE FOR ENTERPRISE LINUX 5.1 Overview

Chapter 1. Red Hat Cluster Suite Overview
Figure 1.17. 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 1.18, "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.
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