Failover Clustering
AggreGate is designed to ensure high availability of provided services. Two-tier failover clustering model comprises:
- AggreGate Server cluster with two or more installations of the platform server
- Underlying storage engine cluster with two or more installations of a database server
The integrated failover clustering engine has some unique features:
| No dependencies on third-party software or operating system services | Cluster nodes may run on different operating systems and hardware |
| Database mirroring is optional and may be implemented using storage engine’s native replication or AggreGate-based database replication module | Platform server cluster nodes may share resources with database cluster nodes |
| Cluster nodes benefit from database load balancing | 3+ nodes cluster remains redundant in case of a master node failure |
AggreGate Server Cluster
Platform-level cluster's objective is reaching almost 100% availability of the server.
The cluster consists of a Master Node, a Primary Failover Node, and zero or more Secondary Failover Nodes. During normal operation, the master node is servicing all operations. All failover nodes are running in standby mode and monitoring the state of a master node.
The primary failover node is automatically switched to Failover Master mode (i.e., activated) in the following cases:
- Network or power outage of the master node
- Major hardware or software failure of the master node
If the cluster has secondary failover nodes, the first of them is switched to Primary Failover mode once the Master Node fails. The whole installation will remain reserved in this case.
Storage Engine Cluster
Database-level cluster's objective is ensuring data integrity by mirroring all data between several physical locations, as well as load balancing during data retrieval operations.
Depending on the storage engine type, database-level failover clustering may be enabled using two different methods:
- Native technology of the storage engine
- AggreGate’s database mirroring technology
