|Red Hat GFS 6.0: Administrator's Guide|
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GNBD multipath allows you to configure multiple GNBD server nodes (nodes that export GNBDs to GFS nodes) with redundant paths between the GNBD server nodes and storage devices. The GNBD server nodes, in turn, present multiple storage paths to GFS nodes (GNBD clients) via redundant GNBDs. With GNBD multipath, if a GNBD server node becomes unavailable, another GNBD server node can provide GFS nodes with access to storage devices.
Make sure to take the following actions when setting up CCS files for GNBD multipath:
Configure a fencing method that physically removes each GNBD server node from the network.
Do not specify the GNBD fencing agent (fence_gnbd) as a fencing device for the GNBD server nodes.
If you specify fence_gnbd as a fence device for a GFS node using GNBD multipath, the fence.ccs file must include an option = multipath parameter (in fence.ccs:fence_devices/DeviceName).
If the GFS node is using another fencing device, the option = multipath parameter is not needed.
For more information about setting up CCS files for GNBD multipath, refer to Section 6.6 Creating the fence.ccs File and Section 6.7 Creating the nodes.ccs File. For more information and additional considerations about using GNBD multipath, refer to Chapter 11 Using GNBD. For more information about fencing, refer to Chapter 10 Using the Fencing System.