Date Added: Jan 2010
The cost of unplanned downtime can be prohibitive, especially in today's economic climate. Thousands of dollars per hour in employee productivity can be lost, along with the potential loss of business - resulting in the competition moving in swiftly to fill the gap. Corporate prestige, and the associated share price, is also at stake. To protect against server failures, the catchword has always been High Availability (HA). For many years, active-passive clustering was used to implement this concept. This typically used the idea of switchable LUNs (Logical Unit Number, in storage parlance) failed-over from one server to another. Database files on the LUN were made accessible to the passive server, and the Oracle instance restarted and recovered there.