Q244. Dual-controller storage: At present, the dual-controller architecture is mainly used in mainstream low-end storage.
Can be divided into Active-Standby and Active-Active mode
– Active- Standby: Also known as HA (High Availability mode, high availability), that is, only one of the two controllers is working at the same time, and the other is waiting, synchronizing and monitoring. Once the primary controller fails, the standby controller takes over its work immediately. At the same time, in order to prevent split-brain, the backup controller needs to power off or restart the main controller through some mechanism before taking over, release its right to use the bus, and then take over the back-end bus and front-end bus.
– Active-Active: Two controllers are working at the same time, each controller is connected to all back- end buses, and each bus is only managed by one of the controllers. Half the number of buses in the backend is managed by one controller and the other half is managed by another controller. If one controller fails, the other takes over all buses. This method is more efficient than the Active-Standby method.
Understanding of the dual-control storage systems, which is correct? (Multiple choice)