This topic describes the specifications of ApsaraDB for Redis Enhanced Edition (Tair) DRAM-based instances that use cloud disks. These specifications include the memory capacity, maximum number of connections to each instance, maximum bandwidth, and queries per second (QPS) reference value.
|Standard||The overall performance of standard instances is as described in the preceding Instance types table.|
|Cluster||The overall performance of cluster instances equals the number of shards multiplied
by the performance of each shard specified by shard specifications.
Note When a cluster instance that runs in proxy mode is accessed, the maximum bandwidth is 2,048 Mbit/s, the maximum total QPS is 10,000,000, and the maximum number of connections is 500,000. To handle ultra-high network traffic for your business, you can enable the direct connection mode. For more information, see Enable the direct connection mode.
The cluster instance provides the following performance:
|Instance type||InstanceClass value (used in API operations)||Number of CPU cores||Memory (GB)||ESSDs capacity (GB)||Number of I/O threads||Maximum bandwidth (Mbit/s)||Number of new connections per second||Maximum number of concurrent connections||QPS reference value|
Notes about CPU cores
To ensure service stability, the system reserves a CPU core to process background tasks. In a cluster instance or a read/write splitting instance, the system reserves a CPU core for each data shard or each read replica to process background tasks.
Calculation rules for bandwidth
- The bandwidth value applies to the upstream and downstream bandwidths. For example, if the bandwidth of an instance is 10 Mbit/s, the upstream and downstream bandwidths of the instance are both 10 Mbit/s.
- The bandwidth column in the preceding Instance types table represents the internal bandwidth of Tair instances. The public bandwidth is determined by the internal bandwidth and is limited by the bandwidth of the connection between a Tair instance and a client. To ensure higher security and lower network latency, we recommend that you connect to a What is a VPC? instance over a virtual private cloud (VPC). For more information about VPCs, see Tair
Notes on connections
The maximum number of new connections per second affects the maximum number of connections at a specific second. For example, assume that the maximum number of new connections per second of an instance is 10,000 and the maximum number of connections of the instance is 50,000. The actual number of connections at the Nth second after the instance starts to run is 12,000. In this case, at the (N+1)th second, the maximum number of connections is 22,000. This value is calculated by using the following formula: 12,000 + 10,000.