Chapter 11. Configuring NVMe over fabrics using NVMe/RDMA

In an Non-volatile Memory Express™ (NVMe™) over RDMA (NVMe™/RDMA) setup, you configure an NVMe controller and an NVMe initiator.

As a system administrator, complete the following tasks to deploy the NVMe/RDMA setup:

11.1. Overview of NVMe over fabric devices

Non-volatile Memory Express™ (NVMe™) is an interface that allows host software utility to communicate with solid state drives.

Use the following types of fabric transport to configure NVMe over fabric devices:

NVMe over Remote Direct Memory Access (NVMe/RDMA)
For information about how to configure NVMe™/RDMA, see Configuring NVMe over fabrics using NVMe/RDMA.
NVMe over Fibre Channel (NVMe/FC)
For information about how to configure NVMe™/FC, see Configuring NVMe over fabrics using NVMe/FC.
NVMe over TCP (NVMe/TCP)
For information about how to configure NVMe/FC, see Configuring NVMe over fabrics using NVMe/TCP.

When using NVMe over fabrics, the solid-state drive does not have to be local to your system; it can be configured remotely through a NVMe over fabrics devices.

11.2. Setting up an NVMe/RDMA controller using configfs

Use this procedure to configure an Non-volatile Memory Express™ (NVMe™) over RDMA (NVMe™/RDMA) controller using configfs.

Prerequisites

  • Verify that you have a block device to assign to the nvmet subsystem.

Procedure

  1. Create the nvmet-rdma subsystem: 

    # modprobe nvmet-rdma

# mkdir /sys/kernel/config/nvmet/subsystems/testnqn

# cd /sys/kernel/config/nvmet/subsystems/testnqn

    Replace testnqn with the subsystem name.

  2. Allow any host to connect to this controller: 

    # echo 1 > attr_allow_any_host

  3. Configure a namespace: 

    # mkdir namespaces/10

# cd namespaces/10

    Replace 10 with the namespace number

  4. Set a path to the NVMe device: 

    # echo -n /dev/nvme0n1 > device_path

  5. Enable the namespace: 

    # echo 1 > enable

  6. Create a directory with an NVMe port: 

    # mkdir /sys/kernel/config/nvmet/ports/1

# cd /sys/kernel/config/nvmet/ports/1

  7. Display the IP address of mlx5_ib0: 

    # ip addr show mlx5_ib0

8: mlx5_ib0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 4092 qdisc mq state UP group default qlen 256
    link/infiniband 00:00:06:2f:fe:80:00:00:00:00:00:00:e4:1d:2d:03:00:e7:0f:f6 brd 00:ff:ff:ff:ff:12:40:1b:ff:ff:00:00:00:00:00:00:ff:ff:ff:ff
    inet 172.31.0.202/24 brd 172.31.0.255 scope global noprefixroute mlx5_ib0
       valid_lft forever preferred_lft forever
    inet6 fe80::e61d:2d03:e7:ff6/64 scope link noprefixroute
       valid_lft forever preferred_lft forever

  8. Set the transport address for the controller: 

    # echo -n 172.31.0.202 > addr_traddr

  9. Set RDMA as the transport type: 

    # echo rdma > addr_trtype

# echo 4420 > addr_trsvcid

  10. Set the address family for the port: 

    # echo ipv4 > addr_adrfam

  11. Create a soft link: 

    # ln -s /sys/kernel/config/nvmet/subsystems/testnqn   /sys/kernel/config/nvmet/ports/1/subsystems/testnqn

Verification

  • Verify that the NVMe controller is listening on the given port and ready for connection requests: 

    # dmesg | grep "enabling port"
[ 1091.413648] nvmet_rdma: enabling port 1 (172.31.0.202:4420)

Additional resources

  • nvme(1) man page

11.3. Setting up the NVMe/RDMA controller using nvmetcli

Use the nvmetcli utility to edit, view, and start an Non-volatile Memory Express™ (NVMe™) controller. The nvmetcli utility provides a command line and an interactive shell option. Use this procedure to configure the NVMe™/RDMA controller by nvmetcli.

Prerequisites

  • Verify that you have a block device to assign to the nvmet subsystem.
  • Execute the following nvmetcli operations as a root user.

Procedure

  1. Install the nvmetcli package: 

    # dnf install nvmetcli

  2. Download the rdma.json file: 

    # wget http://git.infradead.org/users/hch/nvmetcli.git/blob_plain/0a6b088db2dc2e5de11e6f23f1e890e4b54fee64:/rdma.json
  3. Edit the rdma.json file and change the traddr value to 172.31.0.202.

  4. Setup the controller by loading the NVMe controller configuration file: 

    # nvmetcli restore rdma.json
Note

If the NVMe controller configuration file name is not specified, the nvmetcli uses the /etc/nvmet/config.json file.

Verification

  • Verify that the NVMe controller is listening on the given port and ready for connection requests: 

    # dmesg | tail -1
[ 4797.132647] nvmet_rdma: enabling port 2 (172.31.0.202:4420)

  • Optional: Clear the current NVMe controller: 

    # nvmetcli clear

Additional resources

  • nvmetcli and nvme(1) man pages

11.4. Configuring an NVMe/RDMA host

Use this procedure to configure an Non-volatile Memory Express™ (NVMe™) over RDMA (NVMe™/RDMA) host using the NVMe management command line interface (nvme-cli) tool.

Procedure

  1. Install the nvme-cli tool: 

    # dnf install nvme-cli

  2. Load the nvme-rdma module if it is not loaded: 

    # modprobe nvme-rdma

  3. Discover available subsystems on the NVMe controller: 

    # nvme discover -t rdma -a 172.31.0.202 -s 4420

Discovery Log Number of Records 1, Generation counter 2
=====Discovery Log Entry 0======
trtype:  rdma
adrfam:  ipv4
subtype: nvme subsystem
treq:    not specified, sq flow control disable supported
portid:  1
trsvcid: 4420
subnqn:  testnqn
traddr:  172.31.0.202
rdma_prtype: not specified
rdma_qptype: connected
rdma_cms:    rdma-cm
rdma_pkey: 0x0000

  4. Connect to the discovered subsystems: 

    # nvme connect -t rdma -n testnqn -a 172.31.0.202 -s 4420

# lsblk
NAME                         MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda                            8:0    0 465.8G  0 disk
├─sda1                         8:1    0     1G  0 part /boot
└─sda2                         8:2    0 464.8G  0 part
  ├─rhel_rdma--virt--03-root 253:0    0    50G  0 lvm  /
  ├─rhel_rdma--virt--03-swap 253:1    0     4G  0 lvm  [SWAP]
  └─rhel_rdma--virt--03-home 253:2    0 410.8G  0 lvm  /home
nvme0n1

# cat /sys/class/nvme/nvme0/transport
rdma

    Replace testnqn with the NVMe subsystem name.

    Replace 172.31.0.202 with the controller IP address.

    Replace 4420 with the port number.

Verification

  • List the NVMe devices that are currently connected: 

    # nvme list

  • Optional: Disconnect from the controller: 

    # nvme disconnect -n testnqn
NQN:testnqn disconnected 1 controller(s)

# lsblk
NAME                         MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda                            8:0    0 465.8G  0 disk
├─sda1                         8:1    0     1G  0 part /boot
└─sda2                         8:2    0 464.8G  0 part
  ├─rhel_rdma--virt--03-root 253:0    0    50G  0 lvm  /
  ├─rhel_rdma--virt--03-swap 253:1    0     4G  0 lvm  [SWAP]
  └─rhel_rdma--virt--03-home 253:2    0 410.8G  0 lvm  /home

Additional resources

11.5. Next steps