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Tair (Redis® OSS-Compatible):DRAM-based read/write splitting instances

Last Updated:Oct 24, 2024

This topic describes the specifications of DRAM-based read/write splitting instances of ApsaraDB for Redis Enhanced Edition (Tair). These specifications include the number of read replicas, memory capacity, maximum number of connections, maximum bandwidth, and queries per second (QPS) reference value.

Instance specifications

Specification

InstanceClass value (used in API operations)

CPU cores

I/O threads

Read replicas

Bandwidth (Mbit/s)

Maximum new connections per second

Proxy mode: Maximum connections

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 node, 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 node, 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 node, 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 node, 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 shard or read replica to process background tasks.

Calculation rules for bandwidth values

  • Each bandwidth value in the preceding tables represents the maximum bandwidth for an instance of the corresponding instance type, which is the combined bandwidth of all shards or nodes in the instance.

  • The maximum total bandwidth for a read/write splitting instance is 2,048 Mbit/s. After the upper limit is reached, the bandwidth cannot be increased even if you add more nodes to the read/write splitting instance.

  • The bandwidth value applies to the upstream and downstream bandwidths. For example, if the bandwidth of an instance is 96 Mbit/s, the upstream and downstream bandwidths of the instance are both 96 Mbit/s.

    Note

    If your instance may experience an unexpected or anticipated surge in traffic, you can adjust the bandwidth of the instance on demand. For more information, see Manually increase the bandwidth of an instance.

  • The bandwidth limits of Tair and Redis refer to the data transfer capacity of individual shards within their respective distributed systems. The limits are generally independent of the network connection types used by clients to connect to the shards.

For information about the FAQ about bandwidth, see FAQ about bandwidth.

Calculation rules for connections

Item

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

If your instance is created before March 1, 2020 and runs in proxy mode, the maximum number of connections to the instance is 200,000.

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 to the instance is subject to the maximum number of connections to a single shard in direct connection mode. This is because the connections cannot be aggregated in this scenario.

Number of new connections per second

The maximum number of new connections per second refers to the number of connections that can be established per second.

For example, assume that the maximum number of new connections to an instance per second 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 to 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 to the instance per second is subject to the maximum number of connections to a single shard in direct connection mode (2,000). For example, if an instance has four data shards, the maximum number of new connections to the instance per second is 8,000.