Resilience

KooDrive provides a three-level reliability architecture and uses dual-AZ DR, intra-AZ cluster DR, and data DR technologies to ensure service durability and reliability.

**Table 1** KooDrive reliability architecture
Reliability Solution	Description
Dual-AZ DR	KooDrive implements two AZs in active-active mode. When one AZ is abnormal, cloud services can still provide services.
Intra-AZ cluster DR	KooDrive provides services through clusters. Each microservice in a cluster has multiple instances. When one or some instances are abnormal, other instances can continuously provide services.
Data DR	KooDrive data is stored in RDS and DCS. RDS and DCS implement the AZ DR solution. Data is continuously synchronized to the DR site. When the RDS at the production site is faulty, the DR site can take over services, ensures continuous running of cloud services.