What DCS Instance Type Changes Are Supported?

Redis 3.0

From single-node to master/standby

The instance cannot be connected for several seconds and remains read-only for about one minute.

From master/standby to Proxy Cluster

1. If the data of a master/standby DCS Redis 3.0 instance is stored in multiple databases, or in non-DB0 databases, the instance cannot be changed to the Proxy Cluster type. A master/standby instance can be changed to the Proxy Cluster type only if its data is stored only on DB0.
2. The instance cannot be connected and remains read-only for 5 to 30 minutes.

Memcached

From single-node to master/standby

Services are interrupted for several seconds and remain read-only for about 1 minute.

Redis 4.0/5.0/6.0

From master/standby or read/write splitting to Proxy Cluster

1. Before changing the instance type to Proxy Cluster, evaluate the impact on services. For details, see What Are the Constraints on Implementing Multi-DB on a Proxy Cluster Instance? and Command Restrictions.
2. Memory usage must be less than 70% of the maximum memory of the new flavor.
3. Some keys may be evicted if the current memory usage exceeds 90% of the total.
4. After the change, create alarm rules again for the instance.
5. For instances that are currently master/standby, ensure that their read-only IP address or domain name is not used by your application.
6. If your application cannot reconnect to Redis or handle exceptions, you may need to restart the application after the change.
7. Modify instance specifications during off-peak hours. An instance is temporarily interrupted and remains read-only for about 1 minute during the specification change.

From Proxy Cluster to master/standby or read/write splitting

Redis 4.0/5.0/6.0

From master/standby to read/write splitting

1. The instance memory must be greater than or equal to 4 GB, and will remain the same after the change.
2. Some keys may be evicted if the current memory usage exceeds 90% of the total.
3. After the change, create alarm rules again for the instance.
4. Ensure that read-only IP addresses or domain names are not directly referred in the applications using the master/standby instance.
5. If your application cannot reconnect to Redis or handle exceptions, you may need to restart the application after the change.
6. Services may temporarily stutter during the change. Perform the change during off-peak hours.
7. Unavailable for master/standby instances with ACL users.
8. Unavailable for master/standby DCS Redis 6.0 instances with SSL enabled.