How do I use RDMA?

How do I use RDMA?

How Do I Use RDMA? In order to use RDMA, you need a network adapter that has RDMA capability (such as Mellanox’s Connect-X family of adapters). The link layer protocol of the network can be either Ethernet or InfiniBand — both can transfer the RDMA based applications.

How does RDMA Read work?

RDMA is a hardware mechanism through which the network card (NIC) can directly access all or parts of the main memory of a remote node without involving the processor. One-sided RDMA operations do not involve the remote CPU at all. No data is copied between the user space and kernel, and the other way around.

How do I set up RDMA?

Make sure that RDMA is enabled on boot….Setup:

  1. Make sure you have two servers equipped with Mellanox ConnectX-3 adapter cards.
  2. Connect the two servers via an Ethernet switch, you can use access port (VLAN 1 as default)
  3. Install RHEL7 (upsteam kernel) or Ubuntu 14.04 OS on both servers.

What is RDMA service?

In computing, remote direct memory access (RDMA) is a direct memory access from the memory of one computer into that of another without involving either one’s operating system. This permits high-throughput, low-latency networking, which is especially useful in massively parallel computer clusters.

Does RDMA use IP?

5 uses the IP protocol field to differentiate its traffic from other IP protocols such as TCP and UDP. The value used for the protocol number is unspecified and is left to the deployment to select.

What are the main benefits of using RDMA in your network?

The advantages of RDMA is the low latency transfer of information between compute nodes at the memory-to-memory level, without burdening the CPU. This transfer function is offloaded to the network adapter hardware in order to bypass the operating system software network stack.

Should I use RDMA?

beneficial for applications that have irregular access patterns and that are latency sensitive, like key-value stores, graph stores, and relational databases. RDMA networks also provide high bandwidth and high message rates, enabling systems that have high throughput and low latency at the same time.

Does RDMA use TCP?

To show the benefits of RDMA, the test uses SMB Direct enabled (RoCE) and disabled (TCP/IP).

How do you configure RoCE?

Configure RoCE v2 for ConnectX-3 Pro using Mellanox SwitchX switches is needed….Configure the host environment.

  1. Install DCB module, enable DCB in willing mode and remove all previous QoS configuration.
  2. Set the QoS rules, mapping SMB to priority 3 (RoCE).
  3. Enable PFC on priority 3.

How do I enable RDMA on Windows?

4. Configuring Guest RDMA

  1. Install Windows Server 2019.
  2. Install the Hyper-V Role and the Data Center Bridging (DCB) feature.
  3. Configure QoS (Quality-of-Service), DCB, PFC, ETS.
  4. Configure Hyper-V SET (Switch Embedded Team).
  5. Test RDMA communication between the physical servers prior configuring the VMs.

How do I verify my RDMA?

There are two options to do this: using the service file or using lsmod.

  1. Verify that RDMA kernel part is loaded using service file.
  2. Verify that RDMA kernel part is loaded using lsmod.
  3. Verify that RDMA devices are available.
  4. Verify that RDMA devices can be accessed.
  5. Send traffic using ibv_*_pingpong.
  6. Send traffic using rping.

Who invented RDMA?

Cool factoid: RDMA was co-invented by Amazon’s current CTO, Werner Vogels!

What are the advantages of iWarp RDMA network adapters?

One key advantage of iWARP RDMA-capable network adapters is their ability to be routed across different subnets. Although the most common configuration is a single subnet deployment, you can use iWARP network adapters to connect computers across subnets.

What is iWARP and how does it work?

iWARP is a standards-based RDMA implementation running on top of TCP. iWARP addresses current network bottlenecks for high-speed Ethernet and provides high-throughput, low-latency, and low-CPU utilization data communication.

How do I assign an IP address to a rdma1 adapter?

The following Windows PowerShell example shows how to assign an IP address to a network adapter called RDMA1, with an IP address of, a default gateway at, and a DNS server at Because iWARP uses TCP/IP to communicate, you need to configure Windows Firewall to allow TCP/IP traffic.

How does the RDMA model work with the API?

* The layer between the API and the RDMA Model should support memory registration and two forms of data transfer, Send/Receive and RDMA Write/Read. * Long lived memory registrations are used for Send/Receive data transfers. That is, the RDMA library performs a user space copy of the user’s buffer into/out-of a long lived registered buffer.