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6.5. Creating the cluster.ccs File

Creating the cluster.ccs file consists of specifying the following parameters:

NoteNote
 

Because of quorum requirements, the number of lock servers allowed in a GFS cluster can be 1, 3, 4, or 5. Any other number of lock servers — that is, 0, 2, or more than 5 — is not supported.

NoteNote
 

Two optional cluster.ccs parameters, heartbeat_rate and allowed_misses, are included in this procedure for configuring sub-second node failure detection. For a description of other optional parameters, refer to the lock_gulmd(5) man page.

To create the cluster.ccs file, follow these steps:

  1. Create a new file named cluster.ccs using the file structure shown in Figure 6-1. Refer to Table 6-1 for syntax description.

  2. Specify ClusterName (for example, alpha). Refer to Example 6-1.

  3. Specify each node (NodeName) that runs LOCK_GULM server (for example, n01, n02, and n03). Refer to Example 6-1.

  4. (Optional) For the heartbeat rate (heartbeat_rate =), specify Seconds. Refer to Example 6-1.

    The Seconds parameter in combination with the allowed_misses Number parameter specifies the amount of time for node failure detection as follows:

    Seconds x (Number+1) = Time (in seconds)

  5. (Optional) For the allowed consecutively missed heartbeats (allowed_misses =), specify Number. Refer to Example 6-1.

  6. Save the cluster.ccs file.

cluster { 
	  name = "ClusterName" 
	  lock_gulm { 
	      servers = ["NodeName",..., "NodeName"]
              heartbeat_rate = Seconds  <-- Optional 
              allowed_misses = Number   <-- Optional
          } 
}

Figure 6-1. File Structure: cluster.ccs

ParameterDescription
ClusterNameThe name of the cluster, from 1 to 16 characters long.
NodeNameThe name of each node that runs the LOCK_GULM server. Each node name must appear under nodes.ccs:nodes.
Seconds (Optional)For heartbeat_rate, the rate, in seconds, at which a lock server checks heartbeats. To specify a fraction of a second, use floating point notation. For example, to specify a heartbeat rate of three-tenths of a second, set the Seconds parameter to 0.3. Two-thirds of the Seconds parameter is the rate at which the heartbeats are sent by nodes other than the lock server node, preventing heartbeat race conditions. The default value of Seconds is 15. The Seconds parameter in combination with the Number parameter specifies the amount of time for node failure detection as follows: Seconds x (Number+1) = Time (in seconds).
Number (Optional)For allowed_misses, how many consecutive heartbeats can be missed before a node is marked as expired. The default value of Number is 2.The Seconds parameter in combination with the Number parameter specifies the amount of time for node failure detection as follows: Seconds x (Number+1) = Time (in seconds).

Table 6-1. File Syntax Description: Variables for cluster.ccs

cluster { 
         name = "alpha" 
         lock_gulm { 
             servers = ["n01", "n02", "n03"] 
             heartbeat_rate = 0.3
             allowed_misses = 1
         } 
}

Example 6-1. cluster.ccs