ERIs - Elastic Compute Service - Alibaba Cloud Documentation Center

An elastic RDMA interface (ERI) is a virtual network interface that can be bound to an Elastic Compute Service (ECS) instance. ERIs serve as key components in implementing elastic Remote Direct Memory Access (eRDMA) on ECS instances. An ERI is an elastic network interface (ENI) for which the ERI feature is enabled.

Feature description

To configure eRDMA on an ECS instance, you must bind ERIs to the instance. eRDMA is a low-latency, high-throughput, high-performance, and highly scalable Remote Direct Memory Access (RDMA) network service provided by Alibaba Cloud. eRDMA can provide ultra-low-latency and high-throughput network communication for ECS instances by using ERIs. For more information, see Overview.

You can bind ERIs only to ECS instances of specific instance families. For information about the instance families that support ERIs, see Overview of instance families.

To query the maximum number of ERIs that you can bind to an ECS instance of a specific instance type, call the DescribeInstanceTypes operation and check the value of the EriQuantity parameter in the response. A value of 0 indicates that you cannot bind an ERI to an ECS instance of the instance type.

Create an ERI

Create an ERI when you create an ECS instance

If the instance type supports eRDMA, you can enable the ERI feature for ENIs when you create an ECS instance. The configurations vary based on the instance type.

For information about how to configure eRDMA on an enterprise-level instance, see the Configure eRDMA when you create an ECS instance section of the "Configure eRDMA on an enterprise-level instance" topic.

Separately create an ERI

When you create a secondary ENI, turn on eRDMA Interface. The ERI shares the settings of the secondary ENI, including the IP addresses and security group rules of the ENI. For more information, see Create a secondary ENI.

Call an API operation to create an ERI

Call the CreateNetworkInterface operation to create an ENI and set the NetworkInterfaceTrafficMode parameter to HighPerformance to enable the ERI feature for the ENI.

View ERIs

Check whether an ERI is bound to an ECS instance in the ECS console

You can check whether the ERI feature is enabled for an ENI in the ECS console. Perform the following steps:

Log on to the ECS console.
In the left-side navigation pane, choose Instances & Images > Instances.
Find the ECS instance whose ENIs you want to view and click the instance ID to go to the instance details page.
Click the ENIs tab and view detailed information about the ENIs bound to the ECS instance.
If flexible RDMA interface is displayed in the ENI Type column, the ERI feature is enabled for the ENI.

Call an API operation to check whether the ERI feature is enabled for an ENI

Call the DescribeNetworkInterfaceAttribute operation to query the attributes of an ENI and check the value of the NetworkInterfaceTrafficMode parameter in the response to obtain the status of the ERI feature.

Standard: The TCP communication mode is used.
HighPerformance: The ERI feature is enabled and the RDMA communication mode is used.

View the ERIs of an ECS instance after you connect to the instance

After you enable the ERI feature for the ENIs bound to an ECS instance, you can connect to the instance and view the ERIs.

Connect to an ECS instance.
For more information, see Use Workbench to connect to a Linux instance over SSH.
Run the following command to view RDMA devices:
```
ibv_devices
```
The returned device name indicates that the device is an ERI.
If multiple ERI-enabled ENIs are bound to your ECS instance, the following command output is returned.

You can run the ibv_devinfo command to view information about more ERI parameters, such as the port status and the maximum number of queues supported by an ERI.

Change the status of the ERI feature for an existing ENI

Enable the ERI feature for an ENI

When you call the ModifyNetworkInterfaceAttribute operation, set the NetworkInterfaceTrafficMode parameter to HighPerformance and set the NetworkInterfaceId parameter to the ID of the primary ENI or a secondary ENI to enable the ERI feature for the ENI.

Note

You cannot enable the ERI feature for an existing ENI in the ECS console.

Disable the ERI feature for an ENI

You cannot disable the ERI feature for an ENI for which the ERI feature is enabled. However, you can enable or disable the ERI feature for an ECS instance by binding a secondary ENI for which the ERI feature is enabled to the instance or unbinding the secondary ENI from the instance. For more information, see Bind a secondary ENI and Unbind a secondary ENI.