Chapter 2. Using GNBD with Red Hat GFS
GNBD (Global Network Block Device) provides block-level storage access over an Ethernet LAN. GNBD components run as a client in a GFS node and as a server in a GNBD server node. A GNBD server node exports block-level storage from its local storage (either directly attached storage or SAN storage) to a GFS node.
Table 2.1, “GNBD Software Subsystem Components” summarizes the GNBD software subsystems components.
| Software Subsystem | Components | Description |
|---|---|---|
| GNBD | gnbd.ko | Kernel module that implements the GNBD device driver on clients. |
gnbd_export | Command to create, export and manage GNBDs on a GNBD server. | |
gnbd_import | Command to import and manage GNBDs on a GNBD client. | |
gnbd_serv | A server daemon that allows a node to export local storage over the network. |
You can configure GNBD servers to work with device-mapper multipath. GNBD with device-mapper multipath allows you to configure multiple GNBD server nodes to provide redundant paths to the storage devices. The GNBD servers, in turn, present multiple storage paths to GFS nodes via redundant GNBDs. When using GNBD with device-mapper multipath, if a GNBD server node becomes unavailable, another GNBD server node can provide GFS nodes with access to storage devices.
This document how to use GNBD with Red Hat GFS and consists of the following chapters:
- Chapter 3, Considerations for Using GNBD with Device-Mapper Multipath, which describes some of the issues you should take into account when configuring multipathed GNBD server nodes
- Chapter 4, GNBD Driver and Command Usage, which describes the restrictions that apply when you are running GFS on a GNBD server node
- Chapter 5, Running GFS on a GNBD Server Node, which describes the user commands that configure GNBD
