This page lists the shard-level specifications for Tair disk-based instances, including CPU cores, memory, storage, maximum connections, and bandwidth. Tair disk-based instances combine memory with ESSD (Enhanced SSD) or local SSD storage, making them well-suited for large-dataset workloads where only a fraction of the data is accessed frequently.
Instance types
All specifications in the following tables apply to a single shard.
For instances using the standard architecture, overall instance performance equals the single-shard specification.
For instances using the cluster architecture, overall instance performance = single-shard specification x number of shards.
Starting May 8, 2024, when you create a new instance or upgrade an instance type, the maximum connections per shard for disk-based instances is increased to 60,000 or more.
Starting March 14, 2025, Tair will upgrade the following instance types: ESSD-based instances of 32C-128GB or higher (tair.essd.standard.8xlarge, tair.essd.standard.13xlarge, and tair.essd.standard.16xlarge) and SSD-based instances of 32C-256GB (tair.localssd.c1m8.8xlarge and tair.localssd.c1m8.with.proxy.8xlarge). When you create a new instance or upgrade an instance type, the maximum number of connections per shard is increased to 100,000.
Available instance types vary by region, zone, and inventory.
ESSD-based shard specifications
ESSD-based instances support only the standard architecture. The cluster architecture is not supported.
| Instance type name | Instance type code (for API) | CPU cores | Memory (GB) | Optional storage PL and capacity (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 1000 | 60,000 | 2,000 Mbps (250 MB/s) |
| 16C - 64GB | tair.essd.standard.4xlarge | 16 | 64 | PL1: 60 to 1000; PL2: 470 to 2000; PL3: 1270 to 4000 | 60,000 | 3,000 Mbps (375 MB/s) |
| 32C - 128GB | tair.essd.standard.8xlarge | 32 | 128 | PL2: 470 to 4000; PL3: 1270 to 8000 | 100,000 | 5,000 Mbps (625 MB/s) |
| 64C - 256GB | tair.essd.standard.16xlarge | 64 | 256 | PL2: 470 to 8000; PL3: 1270 to 16000 | 100,000 | 8,000 Mbps (1,000 MB/s) |
ESSD performance level 3 (PL3) provides higher IOPS and throughput than PL2 and PL1. For details, see ESSD.
SSD-based shard specifications for standard architecture and cluster architecture in direct connection mode
The following specifications apply to SSD-based instances using the standard architecture or the cluster architecture in direct connection mode. For details about local SSDs, see Local disks.
| Instance type name | Instance type code (for API) | CPU cores | Memory (GB) | Storage capacity (GB) | Maximum connections | Bandwidth |
|---|---|---|---|---|---|---|
| 4C-32GB | tair.localssd.c1m8.xlarge | 4 | 32 | 640 | 60,000 | 1,500 Mbps (187.5 MB/s) |
| 8C-64GB | tair.localssd.c1m8.2xlarge | 8 | 64 | 1,280 | 60,000 | 2,500 Mbps (312.5 MB/s) |
| 16C-128GB | tair.localssd.c1m8.4xlarge | 16 | 128 | 2,560 | 60,000 | 5,000 Mbps (625 MB/s) |
| 32C-256GB | tair.localssd.c1m8.8xlarge | 32 | 256 | 5,120 | 100,000 | 10,000 Mbps (1,250 MB/s) |
SSD-based shard specifications for cluster architecture in proxy mode
| Instance type name | Instance type code (for API) | CPU cores | Memory (GB) | Storage capacity (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-64GB | tair.localssd.c1m8.with.proxy.2xlarge | 8 | 64 | 1,280 | 60,000 | 2,500 Mbps (312.5 MB/s) |
| 16C-128GB | tair.localssd.c1m8.with.proxy.4xlarge | 16 | 128 | 2,560 | 60,000 | 5,000 Mbps (625 MB/s) |
| 32C-256GB | tair.localssd.c1m8.with.proxy.8xlarge | 32 | 256 | 5,120 | 100,000 | 10,000 Mbps (1,250 MB/s) |
Performance description
| Architecture | Performance description |
|---|---|
| Standard architecture | Overall instance performance equals the single-shard specification in the tables above. |
| Cluster architecture in direct connection mode | Overall performance = single-shard specification x number of shards. No overall bandwidth limit applies. |
| Cluster architecture in proxy mode | Overall performance = single-shard specification x number of shards. Maximum bandwidth: 16,384 Mbps (2,048 MB/s). Maximum connections: 500,000. These caps do not increase when you add more shards. |
For example, a cluster instance with four shards using tair.localssd.c1m8.xlarge delivers the following aggregate performance:
| Metric | Per shard | 4-shard total |
|---|---|---|
| CPU cores | 4 | 16 |
| Memory | 32 GB | 128 GB |
| SSD capacity | 640 GB | 2,560 GB |
| Maximum connections | 60,000 | 240,000 |
| Bandwidth | 1,500 Mbps (187.5 MB/s) | 6,000 Mbps (750 MB/s) |
CPU core description
To ensure service stability, the system reserves one CPU core to process background tasks. If an instance uses the cluster or read/write splitting architecture, one CPU core is reserved for each data shard or read-only node to process background tasks.
Bandwidth description
Each bandwidth value in the tables is the maximum bandwidth of a single shard. The total bandwidth of a cluster or read/write splitting instance is the sum of all shard bandwidths.
Cluster instances in proxy mode and read/write splitting instances have a maximum total bandwidth of 16,384 Mbps (2,048 MB/s). Adding more shards does not increase bandwidth beyond this limit. Cluster instances in direct connection mode have no overall bandwidth cap.
Bandwidth applies equally to upstream and downstream traffic. For example, an instance with 768 Mbps (96 MB/s) total bandwidth has 768 Mbps available for both inbound and outbound traffic.
Bandwidth limits reflect the data transfer capacity of individual shards within the distributed system and are generally independent of the client's network connection type.
For answers to common bandwidth questions, see FAQ about bandwidth.
Connection calculation rules
| Category | Description |
|---|---|
| Proxy mode | The maximum connections for an instance is 500,000. Adding more shards does not increase this limit. |
| Direct connection mode | Maximum connections = maximum connections per shard x number of shards. |
Discontinued instance types
The following instance types are no longer available for new instances or upgrades, but existing instances continue to operate normally.
ESSD-based:
| Instance type name | Instance type code (for API) | CPU cores | Memory (GB) | Optional storage PL and capacity (GB) | Maximum connections | Bandwidth |
|---|---|---|---|---|---|---|
| 52C - 192GB | tair.essd.standard.13xlarge | 52 | 192 | PL2: 470 to 6000; PL3: 1270 to 12000 | 100,000 | 8,000 Mbps (1,000 MB/s) |