This topic describes the specifications of read/write splitting DRAM-based instances of Tair. These specifications include the memory capacity, maximum number of connections to each instance, maximum bandwidth, and queries per second (QPS) reference value.
Instance types
| Instance type | InstanceClass value (used in API operations) | Number of CPU cores | Number of I/O threads | Number of read replicas | Maximum bandwidth (MB/s) | Maximum number of new connections per second | Maximum number of connections in proxy mode | QPS reference value |
|---|---|---|---|---|---|---|---|---|
| 1 GB read/write splitting instance (1 shard, 1 read replica) | redis.amber.logic.splitrw.small.1db.1rodb.6proxy.multithread | 12 | 4 | 1 | 192 | 20,000 | 60,000 | 480,000 |
| 2 GB read/write splitting instance (1 shard, 1 read replica) | redis.amber.logic.splitrw.mid.1db.1rodb.6proxy.multithread | 12 | 4 | 1 | 192 | 20,000 | 60,000 | 480,000 |
| 4 GB read/write splitting instance (1 shard, 1 read replica) | redis.amber.logic.splitrw.stand.1db.1rodb.6proxy.multithread | 12 | 4 | 1 | 192 | 20,000 | 60,000 | 480,000 |
| 8 GB read/write splitting instance (1 shard, 1 read replica) | redis.amber.logic.splitrw.large.1db.1rodb.6proxy.multithread | 12 | 4 | 1 | 192 | 20,000 | 60,000 | 480,000 |
| 16 GB read/write splitting instance (1 shard, 1 read replica) | redis.amber.logic.splitrw.2xlarge.1db.1rodb.6proxy.multithread | 12 | 4 | 1 | 192 | 20,000 | 60,000 | 480,000 |
| 32 GB read/write splitting instance (1 shard, 1 read replica) | redis.amber.logic.splitrw.4xlarge.1db.1rodb.6proxy.multithread | 12 | 4 | 1 | 192 | 20,000 | 60,000 | 480,000 |
| 64 GB read/write splitting instance (1 shard, 1 read replica) | redis.amber.logic.splitrw.8xlarge.1db.1rodb.6proxy.multithread | 12 | 4 | 1 | 192 | 20,000 | 60,000 | 480,000 |
| 1 GB read/write splitting instance (1 shard, 3 read replicas) | redis.amber.logic.splitrw.small.1db.3rodb.12proxy.multithread | 24 | 4 | 3 | 384 | 40,000 | 120,000 | 960,000 |
| 2 GB read/write splitting instance (1 shard, 3 read replicas) | redis.amber.logic.splitrw.mid.1db.3rodb.12proxy.multithread | 24 | 4 | 3 | 384 | 40,000 | 120,000 | 960,000 |
| 4 GB read/write splitting instance (1 shard, 3 read replicas) | redis.amber.logic.splitrw.stand.1db.3rodb.12proxy.multithread | 24 | 4 | 3 | 384 | 40,000 | 120,000 | 960,000 |
| 8 GB read/write splitting instance (1 shard, 3 read replicas) | redis.amber.logic.splitrw.large.1db.3rodb.12proxy.multithread | 24 | 4 | 3 | 384 | 40,000 | 120,000 | 960,000 |
| 16 GB read/write splitting instance (1 shard, 3 read replicas) | redis.amber.logic.splitrw.2xlarge.1db.3rodb.12proxy.multithread | 24 | 4 | 3 | 384 | 40,000 | 120,000 | 960,000 |
| 32 GB read/write splitting instance (1 shard, 3 read replicas) | redis.amber.logic.splitrw.4xlarge.1db.3rodb.12proxy.multithread | 24 | 4 | 3 | 384 | 40,000 | 120,000 | 960,000 |
| 64 GB read/write splitting instance (1 shard, 3 read replicas) | redis.amber.logic.splitrw.8xlarge.1db.3rodb.12proxy.multithread | 24 | 4 | 3 | 384 | 40,000 | 120,000 | 960,000 |
| 1 GB read/write splitting instance (1 shard, 5 read replicas) | redis.amber.logic.splitrw.small.1db.5rodb.18proxy.multithread | 36 | 4 | 5 | 576 | 50,000 | 480,000 | 1,440,000 |
| 2 GB read/write splitting instance (1 shard, 5 read replicas) | redis.amber.logic.splitrw.mid.1db.5rodb.18proxy.multithread | 36 | 4 | 5 | 576 | 50,000 | 480,000 | 1,440,000 |
| 4 GB read/write splitting instance (1 shard, 5 read replicas) | redis.amber.logic.splitrw.stand.1db.5rodb.18proxy.multithread | 36 | 4 | 5 | 576 | 50,000 | 480,000 | 1,440,000 |
| 8 GB read/write splitting instance (1 shard, 5 read replicas) | redis.amber.logic.splitrw.large.1db.5rodb.18proxy.multithread | 36 | 4 | 5 | 576 | 50,000 | 480,000 | 1,440,000 |
| 16 GB read/write splitting instance (1 shard, 5 read replicas) | redis.amber.logic.splitrw.2xlarge.1db.5rodb.18proxy.multithread | 36 | 4 | 5 | 576 | 50,000 | 480,000 | 1,440,000 |
| 32 GB read/write splitting instance (1 shard, 5 read replicas) | redis.amber.logic.splitrw.4xlarge.1db.5rodb.18proxy.multithread | 36 | 4 | 5 | 576 | 50,000 | 480,000 | 1,440,000 |
| 64 GB read/write splitting instance (1 shard, 5 read replicas) | redis.amber.logic.splitrw.8xlarge.1db.5rodb.18proxy.multithread | 36 | 4 | 5 | 576 | 50,000 | 480,000 | 1,440,000 |
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 values
- The bandwidth value in the preceding table is the bandwidth of the instance, which is the sum of the bandwidth of all shards or nodes in the instance.
- The upper limit of the total bandwidth for a read/write splitting instance is 2,048 MB/s. After the upper limit is reached, the bandwidth cannot increase even if you add more shards or nodes to the read/write splitting instance.
- The bandwidth value is applicable to the upstream and downstream bandwidths. For example, if the bandwidth of an instance is 10 MB/s, the upstream and downstream bandwidths of the instance are both 10 MB/s. Note If your instance may encounter unexpected or scheduled traffic peaks, you can adjust the bandwidth of the instance. For more information, see Manually adjust the bandwidth of a Tair instance.
- The bandwidth in the preceding tables 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 the client. We recommend that you connect to the instance over an internal network to maximize performance.
Calculation rules for connections
| Category | Description |
|---|---|
| Maximum number of connections | Proxy mode: 480,000. If the upper limit of 480,000 connections is reached, subsequent connections cannot be established even if you add more shards or nodes. Note When you run a specific Pub/Sub, blocking, or transaction command on a cluster instance in proxy mode, the system establishes a dedicated backend connection for your client. In this case, the maximum number of connections for the instance is subject to the maximum number of connections for a single shard in direct connection mode. This is because the connections cannot be aggregated in this scenario. |
| Maximum number of new connections per second | The maximum number of new connections per second refers to the number of connections that are allowed to be established per second. For example, assume that the maximum number of new connections per second for an instance is 50,000 and 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 for the instance is 62,000. This value is calculated by using the following formula: 12,000 + 50,000. Note When you run a specific Pub/Sub, blocking, or transaction command on a cluster instance in proxy mode, the actual number of new connections per second for the instance is subject to the maximum number of connections for a single shard in direct connection mode (2,000). For example, if an instance has four data shards, the maximum number of new connections per second for the instance is 8,000. |