Hi Christoph, The current implementation of RDMA over Fibre channel uses NVMe for the below reasons: 1. Existing FC-NVMe HBA and FC network can be used without requiring any changes. 2. NVMe namespace based discovery is used for RDMA node discovery. 3. FC-NVMe provides us a way to achieve Zero copy TX/RX for non-block workloads. Although we concur with the idea of RDMA directly over Fibre channel, the actual implementation addressing the above reasons requires standardization and coordination with FC HBA vendors and other SAN ecosystem players. This effort is ongoing within our organization (Brocade at Broadcom). However, there is a business case for the current soft RDMA implementation for FC, i.e. RDMA over FC-NVMe, as it provides existing Fibre channel customers a way to utilize existing FC network to transport RDMA workloads as well. While doing this we are making sure NVMe block traffic also can happen on the same FC network. The below link gives more technical details. We are glad to discuss any further details on the same. https://github.com/brocade/RDMAoverFC/blob/master/RDMA%20over%20FC.pdf Regards, Muneendra, Amit & Anand. -----Original Message----- From: Christoph Hellwig [mailto:hch@xxxxxxxxxxxxx] Sent: Wednesday, April 18, 2018 3:52 PM To: muneendra.kumar@xxxxxxxxxxxx Cc: linux-rdma@xxxxxxxxxxxxxxx; amit.tyagi@xxxxxxxxxxxx; anand.sundaram@xxxxxxxxxxxx; linux-nvme@xxxxxxxxxxxxxxxxxxx Subject: Re: [PATCH 1/1] RDMA over Fibre Channel On Wed, Apr 18, 2018 at 02:42:40AM -0700, muneendra.kumar@xxxxxxxxxxxx wrote: > Eventhough it is inspired from the Soft RoCE driver, the underlying > transport layer is FC-NVMe (short for 'NVMe over fibre channel'). > The request, response and completion state machines in the driver have > been heavily modified to adapt to the Exchange based Data transfer > mechanism of Fibre channel. That sounds like a bad joke. Please stop abusing the NVMe code for this otherwise reasonable idea. You should be able to layer this over plain FCP just fine. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
