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Chapter 7. Using the Cluster Configuration System

This chapter describes how to use the cluster configuration system (CCS) and consists of the following sections:

NoteNote
 

If you are using GFS with Red Hat Cluster, you can create a CCS archive with GFS Druid. For information about configuring and using GFS with Red Hat Cluster Suite, refer to Appendix A Using Red Hat GFS with Red Hat Cluster Suite.

NoteNote
 

If your GFS cluster is configured for GNBD multipath, there are some considerations you must take into account for the location of CCS files. Refer to Section 11.1 Considerations for Using GNBD Multipath.

7.1. Creating a CCS Archive

A CCS archive is a collection of CCS configuration files that can be accessed by the cluster. The ccs_tool command is used to create a CCS archive from a directory containing .ccs configuration files. This command writes the archive to a shared pool called the CCA device.

A small pool volume may be used as the CCA device. You can determine the size of the CCA device pool volume as follows: 2 KB per GFS node or 2 MB total, whichever is larger. (Refer to Section 5.5 Creating a Pool Volume and Section 5.6 Activating/Deactivating a Pool Volume for details on creating and activating a pool volume for the CCA device.)

7.1.1. Usage

ccs_tool create Directory CCADevice

Directory

The relative path to the directory containing the CCS files for the cluster.

CCADevice

Specifies the name of the CCA device.

7.1.2. Example

In this example, the name of the cluster is alpha, and the name of the pool is /dev/pool/alpha_cca. The CCS configuration files in directory /root/alpha/ are used to create a CCS archive on the CCA device /dev/pool/alpha_cca.

ccs_tool create /root/alpha/ /dev/pool/alpha_cca

7.1.3. Comments

  • The -O (override) option can be specified after the command name (ccs_tool -O create) to forcibly write over the current CCA device contents without a prompt.

    WarningWarning
     

    Make sure that you specify the right device if you use the override option. Otherwise, data may be lost.

  • Depending on the size of the device, it may take several seconds to create a CCA device for the first time due to initialization of the device.

  • The ccs_tool command uses the Linux raw-device interface to update and read a CCA device directly, bypassing operating system caches. Caching effects could otherwise create inconsistent views of the CCA device between cluster nodes.