Gnbd Driver And Command Usage; Exporting A Gnbd From A Server - Red Hat ENTERPRISE LINUX 5 - GLOBAL NETWORK BLOCK DEVICE Use Manual

Chapter 3.

GNBD Driver and Command Usage

The Global Network Block Device (GNBD) driver allows a node to export its local storage as a GNBD
over a network so that other nodes on the network can share the storage. Client nodes importing the
GNBD use it like any other block device. Importing a GNBD on multiple clients forms a shared storage
configuration through which GFS can be used.
The GNBD driver is implemented through the following components.
• gnbd_serv — Implements the GNBD server. It is a user-space daemon that allows a node to
export local storage over a network.
• gnbd.ko — Implements the GNBD device driver on GNBD clients (nodes using GNBD devices).
Two user commands are available to configure GNBD:
• gnbd_export (for servers) — User program for creating, exporting, and managing GNBDs on a
GNBD server.
• gnbd_import (for clients) — User program for importing and managing GNBDs on a GNBD client.

3.1. Exporting a GNBD from a Server

The gnbd_serv daemon must be running on a node before it can export storage as a GNBD. You
can start the gnbd_serv daemon running gnbd_serv as follows:
#gnbd_serv
gnbd_serv: startup succeeded
Once local storage has been identified to be exported, the gnbd_export command is used to export
it.
Note
When you configure GNBD servers with device-mapper multipath, you must not use page
caching. All GNBDs that are part of a logical volume must run with caching disabled. By
default, the gnbd_export command exports with caching turned off.
Note
A server should not import the GNBDs to use them as a client would. If a server exports
the devices uncached, the underlying devices may also be used by gfs.
Usage
gnbd_export -d pathname -e gnbdname [-c][-u][-U
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