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1.5. Before Configuring GFS

Before you install and configure GFS, note the following key characteristics of your GFS configuration:

Cluster name

Determine a cluster name for your GFS cluster. The cluster name is required in the form of a parameter variable, ClusterName, later in this book.The cluster name can be 1 to 16 characters long. For example, this book uses a cluster name alpha in some example configuration procedures.

Number of file systems

Determine how many GFS file systems to create initially. (More file systems can be added later.)

File system name

Determine a unique name for each file system. Each file system name is required in the form of a parameter variable, FSName, later in this book. For example, this book uses file system names gfs1 and gfs2 in some example configuration procedures.

Number of nodes

Determine how many nodes will mount the file systems. Note the hostname and IP address of each node for use in configuration files later.

LOCK_GULM servers

Determine the number of LOCK_GULM servers. Multiple LOCK_GULM servers (available with RLM) provide redundancy. RLM requires a minimum of three nodes, but no more than five nodes. Information about LOCK_GULM servers is required for a CCS (Cluster Configuration System) file, cluster.ccs. Refer to Section 6.5 Creating the cluster.ccs File for information about the cluster.ccs file.

GNBD server nodes

If you are using GNBD, determine how many GNBD server nodes are needed. Note the hostname and IP address of each GNBD server node for use in configuration files later.

Fencing method

Determine the fencing method for each GFS node. If you are using GNBD multipath, determine the fencing method for each GNBD server node (node that exports GNBDs to GFS nodes). Information about fencing methods is required later in this book for the CCS files, fence.ccs and nodes.ccs. (Refer to Section 6.6 Creating the fence.ccs File and Section 6.7 Creating the nodes.ccs File for more information.) To help determine the type of fencing methods available with GFS, refer to Chapter 10 Using the Fencing System. When using RLM, you must use a fencing method that shuts down and reboots the node being fenced.

Storage devices and partitions

Determine the storage devices and partitions to be used for creating pool volumes in the file systems. Make sure to account for space on one or more partitions for storing cluster configuration information as follows: 2 KB per GFS node or 2 MB total, whichever is larger.