Sun Java System Application Server 9.1 Deployment Planning Guide

Mitigating Double Failures

HADB’s built-in data replication enables it to tolerate failure of a single node or an entire DRU. By default, HADB won’t survive a double failure , when a mirror node pair or both DRUs fail. In such cases, HADB become unavailable.

In addition to using spare nodes as described in the previous section, you can minimize the likelihood of a double failure by taking the following steps:

These steps are optional, but will increase the overall availability of the HADB instance.