Synology High Availability
High Availability refers to a server layout solution designed to reduce interruptions of services caused by server malfunctions. Synology High Availability uses two servers to form a "high-availability cluster" in which one server assumes the role of "active server" and the other server acts as a standby "passive server." In order to implement and create a high-availability cluster, you need two compatible Synology servers.
A high-availability cluster makes use of the following components and concepts:
- Concept: Implementation of Synology High Availability requires two Synology servers to create a high-availability cluster. One server acts as "active server" and the other acts as "passive server." Both the active and passive servers in the high-availability cluster are connected to the same expansion units, and share the same storage in them. To assure the data integrity, only the active server can handle the workload. In the event the active server malfunctions, the passive server will be ready to take over all services. Thus, the high-availability cluster will continue providing services normally, minimizing server downtime. For more details regarding switchover, please refer to Switchover.
- Active server: The active server manages the provision of all services. In the event errors occur on the active server, you or the system can initiate a switchover to the passive server. In this case, the provision of services is transferred to the passive server, at which point the active server becomes the passive server.
- Passive server: Under normal conditions, the passive server remains in standby mode. In the event the active server cannot provide services, you or the system can initiate a switchover to the passive server.
- Heartbeat connection: The active and passive servers of a high-availability cluster are linked by a dedicated, private network connection referred to as "Heartbeat connection." If contact between the servers is lost for a given amount of time, the system will determine a switchover is necessary.
- High-availability cluster shared storage: The drives in the expansion units connected by both active and passive servers at the same time act as the shared storage in the high-availability cluster. Only the active server has the write permissions to the storage.
- High-availability cluster server name and network setting: The server name and network settings of the High-availability cluster will be determined by the corresponding settings in DSM. In the network, you can connect using this server name, and services will be provided by the active server. For more information on network settings, please refer to here.