What does HA Clustering mean?

• HA, High Availability Clustering
• Ensures that mission critical services are available to clients 24/7/365
• In the event of a s/w, h/w or connection failure services are transferred to a fully functional server
• The switchover is fully transparent to clients, a system failure does not impact users' productivity

When it is needed?

• When the system must provide continuous service
• When a potential interruption in service would cause a negative impact
• For example in Database, WWW, Email and E-commerce related services
• When the IT continuity should be ensured without the continuous presence of administrators

With SteelEye LifeKeeper, you are able to run multiple applications in the same cluster without single point of failure. There is no need for front end-servers or separate quorum disk. Each cluster node monitors each other continuously.

Example of basic and common 2-node cluster:

In normal situation:
Server A: Running Oracle
Server B: Running Apache

Server B has failure situation (data, hardware or network reason).
After few seconds:

In failure situation:
Server A: Running Oracle & Apache
Server B: Excluded until restored

Everything is automatical and transparent to clients.