CP server configurations enhance disk-based I/O fencing by providing the following new capabilities:

• CP server configurations are scalable, and a configuration with three CP servers can provide I/O fencing for multiple SFCFSHA clusters. Since a single CP server configuration can serve a large number of SFCFSHA clusters, the cost of multiple SFCFSHA cluster deployments can be significantly reduced.

• Appropriately situated CP servers can eliminate any coordinator disk location bias in the I/O fencing process. For example, this location bias may occur where, due to logistical restrictions, two of the three coordinator disks are located at a single site, and the cost of setting up a third coordinator disk location is prohibitive.

  See Figure: Skewed placement of coordinator disks at Site 1.

  In such a configuration, if the site with two coordinator disks is inaccessible, the other site does not survive due to a lack of a majority of coordination points. I/O fencing would require extension of the SAN to the third site which may not be a suitable solution. An alternative is to place a CP server at a remote site as the third coordination point.