Before purchasing a DCS instance, identify your requirements:
- Decide on the required cache engine.
Choose a cache engine based on service requirements. The cache engine cannot be changed once the instance is created.
- For more information about Redis and Memcached cache engines, see DCS Overview.
- For more information about the differences between Redis and Memcached, see Comparing Redis and Memcached.
- Decide on the required cache engine version.
Perform this step if you choose Redis as the cache engine.
DCS for Redis 3.0 is no longer provided. You can use DCS for Redis 4.0, 5.0, or 6.0 instead.
Different Redis versions have different features. For details, see Comparing DCS Redis Versions.
- Decide on the instance type.
DCS provides single-node, master/standby, Proxy Cluster, and Redis Cluster types of instances. For details about the instance architectures, see DCS Instance Types.
- Decide on the required instance specification.
Each specification specifies the maximum available memory, number of connections, and bandwidth. For details, see DCS Instance Specifications.
- Decide on the region and whether cross-AZ deployment is required.
Choose a region closest to your application to reduce latency.
A region consists of multiple availability zones (AZs) with physically isolated power supplies and networks. Master/standby and cluster DCS instances can be deployed across AZs. Applications can also be deployed across AZs to achieve high availability (HA) for both data and applications.
- If a master/standby or cluster DCS instance is deployed across AZs, faults in an AZ do not affect cache nodes in other AZs. This is because when the master node is faulty, the standby cache node will automatically become the master node to provide services. Such deployment achieves better disaster recovery.
- Deploying a DCS instance across AZs slightly reduces network efficiency compared with deploying an instance within an AZ. Therefore, if a DCS instance is deployed across AZs, synchronization between master and standby cache nodes is slightly less efficient.
- Decide whether backup policies are required.
Currently, backup policies can be configured only for master/standby, Proxy Cluster, and Redis Cluster DCS instances. For details about backup and restoration, see Overview.
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