What is Active-Active Dual Controller NAS architecture and what benefits does it offer?
QNAP dual controller NAS models have two storage controllers. Each storage controller consists of identical CPUs, memory, disk controllers, expansion card slots, fans, and network ports. Each storage controller can access all of the drives installed in the NAS. The storage controllers communicate with each other internally using a non-transparent bridge (NTB) through a common backplane.
Active-Active means that both storage controllers are online at the same time, and work together to provide networking and data storage using protocols such as SMB/CIFS, NFS, and iSCSI. If a storage controller fails, the other storage controller immediately takes over the ownership of storage pools, tasks, and IP addresses from the failed controller, ensuring no interruptions to NAS services.
Benefits of Active-Active Dual Controller NAS architecture:
- Near-zero downtime: automatic storage controller takeover in the event of hardware failure and during firmware updates.
- Hardware redundancy without having idle hardware.
- Reduced cost and power consumption: no need for two NAS devices with two sets of drives.
- No network dependencies for communication and data transfer between storage controllers.
- Load balancing: I/O can be distributed by creating multiple storage pools and distributing pool ownership between the two storage controllers.
- High-availability for SAS expansion units when connected to both storage controllers using dual-path cabling.
