Red Hat GFS 5.2.1 -, Administrator'S Manual

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114 Chapter 11. Using GNBD
Note
If FC-attached storage can be shared among nodes, the CCS files can be stored on that shared
storage.
Note
A node with CCS files stored on local storage or FC-attached storage can serve the CCS files to
other nodes in a GFS cluster via
ccs_servd
. However, doing so would introduce a single point of
failure. For information about
ccs_servd
, refer to Section 7.5.1 CCA File and Server .
Table 11-1 summarizes where CCS files can be located according to node deployment. For information
about using CCS, refer to Chapter 7 Using the Cluster Configuration System .
Node Deployment CCS File Location
GFS dedicated GNBD, local, or FC-attached storage
GFS with lock server Local or FC-attached storage only
GNBD server dedicated Local or FC-attached storage only
GNBD server with lock server Local or FC-attached storage only
Lock server dedicated Local or FC-attached storage only
Table 11-1. CCS File Location for GNBD Multipath Cluster
11.1.4. Fencing GNBD Server Nodes
GNBD server nodes must be fenced using a fencing method that physically removes the nodes from
the network and notifies the GFS nodes that the GNBD server node has been fenced. To physically
remove a GNBD server node, you can use any of the following fencing devices: APC MasterSwitch
(
fence_apc
fence agent), WTI NPS (
fence_wti
fence agent), Brocade (
fence_brocade
fence
agent), Vixel (
fence_vixel
fence agent) or HP RILOE (
fence_rib
fence agent). You cannot
use the GNBD fencing device (
fence_gnbd
fence agent) to fence a GNBD server node. In addi-
tion, the fencing method used for GNBD server nodes must include a fencing device that uses the
fence_notify_gnbd
fencing agent for notifying GFS nodes that a GNBD server has been fenced.
For information about the
fence_notify_gnbd
fence agent, refer to Section 10.2.7 Fence Notify
GNBD . For information about configuring fencing for GNBD server nodes, refer to Chapter 6 Creat-
ing the Cluster Configuration System Files .
11.2. 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.