A database cluster is a group of multiple servers that work together to provide high availability and scalability for a database. They are managed by a single instance of a DBMS, which provides a unified view of the data stored in the cluster.
Database clustering boosts availability and scalability. Multiple servers offer increased bandwidth, storage, and performance. Plus, clustering ensures the database stays available if a server fails.
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Types of Database Cluster
Databases can be clustered in two primary ways: active-active and active-passive.
In an active-active cluster, all servers handle requests. This boosts performance, but it can also increase complexity and demand more hardware.
In an active-passive cluster, one server acts as the primary, while the others serve as backups. If the primary server fails, a backup server takes over.
- Active-active: All servers process requests
- Active-passive: Primary server with backups
- Active-active: Better performance but complex
When does a Database need to be Clustered?
Deciding to cluster a database often hinges on performance. If the database faces constant use and overload, clustering can help spread the load and enhance performance.
Databases often need clustering when they grow too large or complicated for one server. Clustering is also common for ensuring high availability. If a database needs 24/7 uptime, clustering helps keep the system running even if a node fails.
- Performance improvement
- Handling large or complex data
- Ensuring high availability
Benefits of Database Cluster
Using a database cluster offers several key advantages:
High Availability
A database cluster offers high availability since multiple servers are involved. If one server fails, others take over to keep the system running. This prevents any single point of failure.
Load Balancing
A database cluster offers load balancing. If one server is facing high loads, the cluster distributes this load across all servers. This ensures optimal server utilization and prevents any server from overloading.
Fault Tolerance
Additionally, a database cluster offers fault tolerance. If one server fails, others in the cluster continue to operate, ensuring the system remains available.
Improved Performance
A database cluster can boost performance. By spreading data over multiple servers, it optimizes overall efficiency. Using load balancing makes sure all servers are active and no single server gets overloaded.