Data mirroring
Review this section to better understand the importance of data mirroring.
Configurations that allow users to access data can have different levels of protection against data loss. Consider the following data access configurations at a high level. All these configurations enable users to have access to data, with increasing levels of data protection against loss:
Single server with one data copy
In the following configuration, a single copy of mission-critical data spans two disks. Either disk is potentially a single point of failure:
Single server with standard AIX® LVM mirroring
The following configuration has two more disks that contain a second mirror copy. However, the server is still a potential single point of failure.
PowerHA® SystemMirror® cluster with standard AIX LVM mirroring
The following configuration is based on a PowerHA SystemMirror cluster that uses AIX LVM mirroring:
This configuration eliminates most potential single points of failure. However, a disaster can wipe out the entire cluster along with all copies of mission critical data.
Two-site PowerHA SystemMirror cluster with GLVM mirroring
Finally, the configuration shown in the following image contains two sites with nodes at each site. One volume group actually spans both sites. Each site contains a mirror copy of mission critical data. Instead of extremely long disk cables, a TCP/IP network and the RPV device driver are used to enable remote disk access.
