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    Tair (Redis® OSS-Compatible):ESSD/SSD-based instances

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    Tair (Redis® OSS-Compatible):ESSD/SSD-based instances

    Last Updated:Jun 09, 2025

    This topic describes the specifications of Tair (Enterprise Edition) ESSD/SSD-based instances. The specifications include the memory capacity, maximum number of connections, and maximum bandwidth.

    Instance specifications

    The following tables list the specifications of individual shards.

    • The overall performance of a standard instance is determined by the specifications of the shards in the instance.

    • The overall performance of a cluster instance can be estimated by multiplying the performance of a single shard by the total number of shards in the instance.

      Note

      • Starting May 8, 2024, the maximum number of connections to each shard of an ESSD/SSD-based instance is increased to 60,000 or more. This increase applies when you create an instance or upgrade the specifications of an existing instance. For specific information, see the following table.

      • Starting March 14, 2025, Tair (Enterprise Edition) upgrades ESSD-based instances of the 32C - 128GB specification or higher (tair.essd.standard.8xlarge, tair.essd.standard.13xlarge, and tair.essd.standard.16xlarge) and SSD-based instances of the 32C - 256GB specification or higher (tair.localssd.c1m8.8xlarge and tair.localssd.c1m8.with.proxy.8xlarge). When you create instances or upgrade the specifications of existing instances, the maximum number of connections per shard is increased to 100,000.

      • Instances that can be created in different regions and zones are subject to actual inventory.

    Shard specifications of ESSD-based instances

    ESSD-based instances support only the standard architecture.

    Specification type

    InstanceClass value (used in API operations)

    CPU cores

    Memory (GB)

    Storage performance level and capacity range (GB)

    Maximum connections

    Bandwidth

    4C - 16GB

    tair.essd.standard.xlarge

    4

    16

    PL1: 60 to 250

    60,000

    1,500 Mbps (187.5 MB/s)

    8C - 32GB

    tair.essd.standard.2xlarge

    8

    32

    PL1: 60 to 500

    PL2: 470 to 1,000

    60,000

    2,000 Mbps (250 MB/s)

    16C - 64GB

    tair.essd.standard.4xlarge

    16

    64

    PL1: 60 to 1,000

    PL2: 470 to 2,000

    PL3: 1,270 to 4,000

    60,000

    3,000 Mbps (375 MB/s)

    32C - 128GB

    tair.essd.standard.8xlarge

    32

    128

    PL2: 470 to 4,000

    PL3: 1,270 to 8,000

    100,000

    5,000 Mbps (625 MB/s)

    52C - 192GB

    tair.essd.standard.13xlarge

    52

    192

    PL2: 470 to 6,000

    PL3: 1,270 to 12,000

    100,000

    8,000 Mbps (1,000 MB/s)

    64C - 256GB

    tair.essd.standard.16xlarge

    64

    256

    PL2: 470 to 8,000

    PL3: 1,270 to 16,000

    100,000

    8,000 Mbps (1,000 MB/s)

    Note

    Enterprise SSDs at performance level 3 (PL3 ESSDs) perform better than PL2 and PL1 ESSDs. For more information, see ESSDs.

    Shard specifications of SSD-based standard instances and cluster instances in direct connection mode

    The following specifications are applicable to SSD-based standard instances and cluster instances in direct connection mode.

    Specification type

    InstanceClass value (used in API operations)

    CPU cores

    Memory (GB)

    Storage performance level and capacity range (GB)

    Maximum connections

    Bandwidth

    4C-32GB

    tair.localssd.c1m8.xlarge

    4

    32

    640

    60,000

    1,500 Mbps (187.5 MB/s)

    8C-32GB

    tair.localssd.c1m4.2xlarge

    8

    32

    320

    60,000

    3,000 Mbps (375 MB/s)

    8C-64GB

    tair.localssd.c1m8.2xlarge

    8

    64

    1,280

    60,000

    2,500 Mbps (312.5 MB/s)

    16C-64GB

    tair.localssd.c1m4.4xlarge

    16

    64

    640

    60,000

    5,000 Mbps (625 MB/s)

    32C-128GB

    tair.localssd.c1m4.8xlarge

    32

    128

    1,280

    100,000

    12,000 Mbps (1,500 MB/s)

    Shard specifications of SSD-based cluster instances in proxy mode

    The following specifications are applicable to SSD-based cluster instances in proxy mode.

    Specification type

    InstanceClass value (used in API operations)

    CPU cores

    Memory (GB)

    Storage performance level and capacity range (GB)

    Maximum connections

    Bandwidth

    4C-32GB

    tair.localssd.c1m8.with.proxy.xlarge

    4

    32

    640

    60,000

    1,500 Mbps (187.5 MB/s)

    8C-32GB

    tair.localssd.c1m4.with.proxy.2xlarge

    8

    32

    320

    60,000

    3,000 Mbps (375 MB/s)

    8C-64GB

    tair.localssd.c1m8.with.proxy.2xlarge

    8

    64

    1,280

    60,000

    2,500 Mbps (312.5 MB/s)

    16C-64GB

    tair.localssd.c1m4.with.proxy.4xlarge

    16

    64

    640

    60,000

    5,000 Mbps (625 MB/s)

    32C-128GB

    tair.localssd.c1m4.with.proxy.8xlarge

    32

    128

    1,280

    60,000

    12,000 Mbps (1,500 MB/s)

    Performance description

    Architecture

    Performance description

    Standard architecture

    The overall performance of standard instances is the same as that described in the preceding instance specification tables.

    Cluster architecture in direct connection mode

    Cluster architecture in proxy mode

    Overall performance of an instance = Performance of a shard × Number of shards.

    Note

    When a cluster instance that runs in proxy mode is accessed, the maximum bandwidth is 16,384 Mbps (2,048 MB/s), the maximum total QPS is 10,000,000, and the maximum number of connections is 500,000.

    For example, an instance that contains four shards of the tair.localssd.c1m4.with.proxy.2xlarge type has the following specifications:

    • Number of CPU cores: 8

    • Memory: 32 GB

    • SSD capacity: 320 GB

    • Number of connections: 60,000

    • Bandwidth: 3,000 Mbps (375 MB/s)

    In this case, the instance provides the following performance:

    • Number of CPU cores: 32

    • Memory: 128 GB

    • SSD capacity: 1,280 GB

    • Number of connections: 240,000

    • Bandwidth: 12,000 Mbps (1,500 MB/s)

    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.

    Bandwidth description

    • Each bandwidth value in the preceding tables represents the maximum bandwidth of a single shard. The total bandwidth of a cluster or read/write splitting instance is the combined bandwidth of all shards in the instance.

    • The maximum bandwidth of a cluster instance in proxy mode or a read/write splitting instance is 16,384 Mbps (2,048 MB/s). After the upper limit is reached, the bandwidth cannot be increased even if you add more shards to the instance. Cluster instances in direct connection mode have no limits on the overall bandwidth.

    • The bandwidth applies to the upstream and downstream bandwidths. For example, if the overall bandwidth of an instance is 768 Mbps (96 MB/s), the upstream and downstream bandwidths of the instance are both 768 Mbps (96 MB/s).

    • The bandwidth limits of Tair and Redis Open-Source Edition 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: 500,000. If the upper limit of 500,000 connections is reached, subsequent connections cannot be established even if you add more shards.

    • Direct connection mode: Maximum number of connections to an instance = Maximum number of connections to a shard × Number of shards.