In most cases it is recommended that you use the global detach policy, and particularly if any of the following conditions apply:

• When cluster-wide access to the shared data volumes is more critical than retaining data redundancy.

• If only non-mirrored, small mirrored, or hardware mirrored volumes are configured. In these cases, the global detach policy avoids the system overhead of the extra messaging that the local detach policy requires.

The local detach policy may be suitable in the following cases:

• When large mirrored volumes are configured - Resynchronizing a reattached plex can degrade system performance. The local detach policy can avoid the need to detach the plex at all. (Alternatively, the dirty region logging (DRL) feature can be used to reduce the amount of resynchronization that is required.)

• For clusters with more than four nodes - Keeping an application running on a particular node is less critical when there are many nodes in a cluster. It may be possible to configure the cluster management software to move an application to a node that has access to the volumes. In addition, load balancing may be able to move applications to a different volume from the one that experienced the I/O problem. This preserves data redundancy, and other nodes may still be able to perform I/O from/to the volumes on the disk.