Multi-Site Cluster Configuration Considerations

Before you begin configuring your systems, it’s important to understand what hierarchy configurations you should avoid in the Linux Multi-Site Cluster hierarchy environment.

Below are three examples of hierarchy configurations that should be avoided in the Linux Multi-Site Cluster environment. In all these cases, a Linux Multi-Site Cluster hierarchy shares an underlying device with another hierarchy. Failure or switchover of either hierarchy will impact the associated hierarchy. This could possibly produce unintended consequences such as application failure or mirror breakage; which would require a full-resync process later. In addition, complications could result when switching the mirror sources to the DR site allowing it to mirror back to the primary site since the mirror target system will have the lower level disk resources in service. Any shared resources must also be operational (ISP) on the same node as the mirror target.

Example	Description
1	Using the Multi-Site Cluster hierarchy’s mirror disk resource more than once in the same or different hierarchies.
2	Using the same Multi-Site Cluster file system or disk resource for the mirror bitmap in more than one Multi-Site Cluster hierarchy. (Each mirror’s bitmap file must reside on a unique LUN and can’t be shared.)
3	Using the bitmap file system, device or disk resource with another hierarchy (Multi-Site or non-Multi-Site).