The following architecture shows an ApsaraDB for Cassandra instance that contains two data centers. Each data center contains four nodes.
An ApsaraDB for Cassandra instance can contain one to three data centers. Each data center contains one to 500 nodes. A Cassandra process is deployed on each node.
ApsaraDB for Cassandra instances do not adopt the master-proxy node architecture. All the nodes are peers. Logically, the system specifies two nodes in each data center as the seed nodes. However, seed nodes do not require process deployment because seed nodes bring little impact on the system.
The client connects to each server node to ensure high performance.
The number of replicas of each data center can be customized. Replicas can be used for data center disaster recovery, backup, and offline analysis.
The storage space of a node ranges from 160 GB to 16 TB. The storage space of 500 nodes is 8000 TB that is about 8 PB.