Ways that availability is affected by data sharing

Availability during an outage

A significant availability benefit during a planned or unplanned outage of a Db2 group member is that Db2 data remains available through other group members. Some common situations when you might plan for an outage include applying software maintenance, changing a system parameter, or migrating to a new release. For example, during software maintenance, you can apply the maintenance to one member at a time, which leaves other Db2 members available to do work.

Coupling facility availability

When planning your data sharing configuration for the highest availability, you must monitor the physical protection of the coupling facility and the structures within the coupling facility.

For high availability, you must have at least two coupling facilities. One of coupling facility must be physically isolated. The isolated coupling facility must reside in a CPC that does not also contain a Db2 member that is connected to structures in that coupling facility. With at least two coupling facilities, you can avoid a single point of failure.

Duplexing group buffer pools

With more than one coupling facility, you can also consider duplexing the group buffer pools. With duplexing, a secondary group buffer pool is available on standby in another coupling facility, ready to take over if the primary group buffer pool structure fails or if a connectivity failure occurs.

Running some or all of your group buffer pools in duplex mode is one way to achieve high availability for group buffer pools across many types of failures, including lost connections and damaged structures.