Difference between Infiniband and RDMA

Question

Man pages of linux command ibstat and ibv_devinfo say

ibstat - query basic status of InfiniBand device(s)
ibv_devinfo - query RDMA devices

In this context, what is the difference between Infiniband devices and RDMA devices? And in what circumstances, are the outputs of these two commands different (i.e. they differ in the list of devices output)?

Answer 1

There is no difference between "InfiniBand device" and "RDMA device" in this context. It is just two separate tools written by different people that prefer different type of wording.

Both of these tools will provide you with the same devices.

That said, these two tools are completely different:

• ibstat gets its info from sysfs - it gets whatever info is there, and that info is put by an HCA driver
• ibv_devinfo uses verbs to query the device and provide you with the info

There are some bits of info that you can see with one tool but not with other, but again, in general, you will see the same devices with same info.