10.1 Planning for Cluster Resources

Consider the guidelines in this section when planning for your cluster resources.

10.1.1 Naming Conventions for Cluster Resources

Cluster resource names can be up to 63 characters. Novell Cluster Services supports only alphanumeric characters and the underscore character in cluster resource names:

ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_

Special characters, such as the following, are not supported in cluster resource names:

!@#$%&()

Because the NSS pool name and Linux volume names are automatically used in the cluster resource name, do not use special characters !@#$%&() in names of NSS pools or Linux POSIX volumes that you plan to cluster enable.

10.1.2 Using Parameter Values with Spaces in a Cluster Script

In cluster scripts, if a parameter value contains spaces, you should enclose the value with both double-quotes (") and single-quotes ('). For example, "'quoted text'". The preferred solution is to use both sets of quotation marks with the single-quotes on the inside. For OES 11 and later, the other order also works for spaces, but it reads a variable as text, not as a variable.

For example, either of the following techniques works for values with spaces:

exit_on_error echo "'Errors will be reported here.'"

exit_on_error echo '"Errors will be reported here."'

You can alternatively use two sets of double-quotes and escape the inside set of double-quotes with a backslash (\). For example:

exit_on_error echo "\"Errors will be reported here.\""

Another alternative is to escape each of the spaces in the value. For example:

exit_on_error echo Errors\ will\ be\ reported\ here.

10.1.3 Using Double Quotation Marks in a Cluster Script

In cluster scripts, if a command requires double-quotation marks, you should enclose the quoted part of the command with both double-quotes (") and single-quotes ('), such as "'quoted text'". The key is to use both sets of quotation marks with the single-quotes on the inside. This works for spaces and allows you to pass variables to the command. For example:

exit_on_error echo "'Errors will be reported here.'"

You can alternatively use two sets of double-quotes and escape the inside set of double-quotes with a backslash (\). For example:

exit_on_error echo "\"Errors will be reported here.\""

10.1.4 Script Length Limits

Each cluster load, unload, or monitor script can be up to 3200 bytes in length. This limit includes commands, comments, and spaces. For example, non-special ASCII characters (including the space character) are 1 byte per character, so you could have up to 3200 of these characters in a script.

IMPORTANT:Creating a script that exceeds the maximum script length can prevent a resource from loading. If your script commands and comments require more memory than 3200 bytes, you can spawn external scripts from a script.

10.1.5 Planning Cluster Maintenance

When performing cluster maintenance tasks, two cluster best practices should be observed:

  • Perform maintenance tasks during non-peak hours so that users are minimally affected.

  • Before performing maintenance on a node, cluster migrate its cluster resources to another node if you want the related users to be undisturbed.

10.1.6 Number of Resources

Novell Cluster Services supports up to 254 resources in a cluster, regardless of the size of the cluster.

10.1.7 Linux POSIX File System Types

Ext3 is the default file system type used in the Generic File System template scripts. The Btrfs, Ext2, Ext3, ReiserFS, and XFS file systems have been tested and are fully supported.