Jump to contentJump to page navigation: previous page [access key p]/next page [access key n]
documentation.suse.com / SUSE Linux Enterprise Server Documentation / Storage Administration Guide / Network Storage / NVMe over Fabric
Applies to SUSE Linux Enterprise Server 15 SP2

17 NVMe over Fabric

This chapter describes how to set up an NVMe over Fabric host and target.

17.1 Overview

NVM Express (NVMe) is an interface standard for accessing non-volatile storage, commonly SSD disks. NVMe supports much higher speeds and has a lower latency than SATA.

NVMe over Fabric is an architecture to access NVMe storage over different networking fabrics, for example RDMA, TCP or NVMe over Fibre Channel (FC-NVMe). The role of NVMe over Fabric is similar to iSCSI. To increase the fault-tolerance, NVMe over Fabric has a built-in support for multipathing. The NVMe over Fabric multipathing is not based on the traditional DM-Multipathing.

The NVMe host is the machine that connects to an NVMe target. The NVMe target is the machine that shares its NVMe block devices.

NVMe is supported on SUSE Linux Enterprise Server 15 SP2. There are Kernel modules available for the NVMe block storage and NVMe over Fabric target and host.

To see if your hardware requires any special consideration, refer to Section 17.4, “Special Hardware Configuration”.

17.2 Setting Up an NVMe over Fabric Host

To use NVMe over Fabric, a target must be available with one of the supported networking methods. Supported are NVMe over Fibre Channel, TCP and RDMA. The following sections describe how to connect a host to an NVMe target.

17.2.1 Installing Command Line Client

To use NVMe over Fabric, you need the nvme command line tool. Install it with zypper:

> sudo zypper in nvme-cli

Use nvme --help to list all available subcommands. Man pages are available for nvme subcommands. Consult them by executing man nvme-SUBCOMMAND. For example, to view the man page for the discover subcommand, execute man nvme-discover.

17.2.2 Discovering NVMe over Fabric Targets

To list available NVMe subsystems on the NVMe over Fabric target, you need the discovery controller address and service ID.

> sudo nvme discover -t TRANSPORT -a DISCOVERY_CONTROLLER_ADDRESS -s SERVICE_ID

Replace TRANSPORT with the underlying transport medium: loop, rdma, tcp or fc. Replace DISCOVERY_CONTROLLER_ADDRESS with the address of the discovery controller. For RDMA and TCP this should be an IPv4 address. Replace SERVICE_ID with the transport service ID. If the service is IP based, like RDMA or TCP, service ID specifies the port number. For Fibre Channel, the service ID is not required.

The NVMe hosts only see the subsystems they are allowed to connect to.

Example:

> sudo nvme discover -t tcp -a 10.0.0.3 -s 4420

For more details, see man nvme-discover.

17.2.3 Connecting to NVMe over Fabric Targets

After you have identified the NVMe subsystem, you can connect it with the nvme connect command.

> sudo nvme connect -t transport -a DISCOVERY_CONTROLLER_ADDRESS -s SERVICE_ID -n SUBSYSTEM_NQN

Replace TRANSPORT with the underlying transport medium: loop, rdma, tcp or fc. Replace DISCOVERY_CONTROLLER_ADDRESS with the address of the discovery controller. For RDMA and TCP this should be an IPv4 address. Replace SERVICE_ID with the transport service ID. If the service is IP based, like RDMA or TCP, this specifies the port number. Replace SUBSYSTEM_NQN with the NVMe qualified name of the desired subsystem as found by the discovery command. NQN is the abbreviation for NVMe Qualified Name. The NQN must be unique.

Example:

> sudo nvme connect -t tcp -a 10.0.0.3 -s 4420 -n nqn.2014-08.com.example:nvme:nvm-subsystem-sn-d78432

Alternatively, use nvme connect-all to connect to all discovered namespaces. For advanced usage see man nvme-connect and man nvme-connect-all.

To make an NVMe over Fabrics subsytem available at boot, create a /etc/nvme/discovery.conf file on the host with the parameters passed to the discover command (as described in Section 17.2.2, “Discovering NVMe over Fabric Targets”. For example, if you use the discover command as follows:

> sudo nvme discover -t tcp -a 10.0.0.3 -s 4420

Add the parameters of the discover command to the /etc/nvme/discovery.conf file:

echo "-t tcp -a 10.0.0.3 -s 4420" | sudo tee -a /etc/nvme/discovery.conf

Then enable the nvmf-autoconnect service:

> sudo systemctl enable nvmf-autoconnect.service

17.2.4 Multipathing

NVMe native multipathing is enabled by default. If the CMIC option in the controller identity settings is set, the NVMe stack recognizes an NVME drive as a multipathed device by default.

To manage the multipathing, you can use the following:

Managing multipathing
nvme list-subsys

Prints the layout of the multipath devices.

multipath -ll

The command has a compatibility mode and displays NVMe multipath devices.

nvme-core.multipath=N

When the option is added as a boot parameter, the NVMe native multipathing will be disabled.

Note
Note: Using iostat in multipath setups

The iostat command might not show all controllers that are listed by nvme list-subsys. By default, iostat filters out all block devices with no I/O. To make iostat show all devices, use:

iostat -p ALL

17.3 Setting Up an NVMe over Fabric Target

17.3.1 Installing Command Line Client

To configure an NVMe over Fabric target, you need the nvmetcli command line tool. Install it with zypper:

> sudo zypper in nvmetcli

The current documentation for nvmetcli is available at http://git.infradead.org/users/hch/nvmetcli.git/blob_plain/HEAD:/Documentation/nvmetcli.txt.

17.3.2 Configuration Steps

The following procedure provides an example of how to set up an NVMe over Fabric target.

The configuration is stored in a tree structure. Use the command cd to navigate. Use ls to list objects. You can create new objects with create.

  1. Start the nvmetcli interactive shell:

    > sudo nvmetcli
  2. Create a new port:

    (nvmetcli)> cd ports
    (nvmetcli)> create 1
    (nvmetcli)> ls 1/
    o- 1
      o- referrals
      o- subsystems
  3. Create an NVMe subsystem:

    (nvmetcli)> cd /subsystems
    (nvmetcli)> create nqn.2014-08.org.nvmexpress:NVMf:uuid:c36f2c23-354d-416c-95de-f2b8ec353a82
    (nvmetcli)> cd nqn.2014-08.org.nvmexpress:NVMf:uuid:c36f2c23-354d-416c-95de-f2b8ec353a82/
    (nvmetcli)> ls
    o- nqn.2014-08.org.nvmexpress:NVMf:uuid:c36f2c23-354d-416c-95de-f2b8ec353a82
      o- allowed_hosts
      o- namespaces
  4. Create a new namespace and set an NVMe device to it:

    (nvmetcli)> cd namespaces
    (nvmetcli)> create 1
    (nvmetcli)> cd 1
    (nvmetcli)> set device path=/dev/nvme0n1
    Parameter path is now '/dev/nvme0n1'.
  5. Enable the previously created namespace:

    (nvmetcli)> cd ..
    (nvmetcli)> enable
    The Namespace has been enabled.
  6. Display the created namespace:

    (nvmetcli)> cd ..
    (nvmetcli)> ls
    o- nqn.2014-08.org.nvmexpress:NVMf:uuid:c36f2c23-354d-416c-95de-f2b8ec353a82
      o- allowed_hosts
      o- namespaces
        o- 1
  7. Allow all hosts to use the subsystem. Only do this in secure environments.

    (nvmetcli)> set attr allow_any_host=1
    Parameter allow_any_host is now '1'.

    Alternatively, you can allow only specific hosts to connect:

    (nvmetcli)> cd nqn.2014-08.org.nvmexpress:NVMf:uuid:c36f2c23-354d-416c-95de-f2b8ec353a82/allowed_hosts/
    (nvmetcli)> create hostnqn
  8. List all created objects:

    (nvmetcli)> cd /
    (nvmetcli)> ls
    o- /
      o- hosts
      o- ports
      | o- 1
      |   o- referrals
      |   o- subsystems
      o- subsystems
        o- nqn.2014-08.org.nvmexpress:NVMf:uuid:c36f2c23-354d-416c-95de-f2b8ec353a82
          o- allowed_hosts
          o- namespaces
            o- 1
  9. Make the target available via TCP. Use trtype=rdma for RDMA:

    (nvmetcli)> cd ports/1/
    (nvmetcli)> set addr adrfam=ipv4 trtype=tcp traddr=10.0.0.3 trsvcid=4420
    Parameter trtype is now 'tcp'.
    Parameter adrfam is now 'ipv4'.
    Parameter trsvcid is now '4420'.
    Parameter traddr is now '10.0.0.3'.

    Alternatively, you can make it available with Fibre Channel:

    (nvmetcli)> cd ports/1/
    (nvmetcli)> set addr adrfam=fc trtype=fc traddr=nn-0x1000000044001123:pn-0x2000000055001123 trsvcid=none
  10. Link the subsystem to the port:

    (nvmetcli)> cd /ports/1/subsystems
    (nvmetcli)> create nqn.2014-08.org.nvmexpress:NVMf:uuid:c36f2c23-354d-416c-95de-f2b8ec353a82

    Now you can verify that the port is enabled using dmesg:

    # dmesg
            ...
    [  257.872084] nvmet_tcp: enabling port 1 (10.0.0.3:4420)

17.3.3 Back Up and Restore Target Configuration

You can save the target configuration in a JSON file with the following commands:

> sudo nvmetcli
(nvmetcli)> saveconfig nvme-target-backup.json

To restore the configuration, use:

(nvmetcli)> restore nvme-target-backup.json

You can also wipe the current configuration:

(nvmetcli)> clear

17.4 Special Hardware Configuration

17.4.1 Overview

Some hardware needs special configuration to work correctly. Skim the titles of the following sections to see if you are using any of the mentioned devices or vendors.

17.4.2 Broadcom

If you are using the Broadcom Emulex LightPulse Fibre Channel SCSI driver, add a Kernel configuration parameter on the target and host for the lpfc module:

> sudo echo "options lpfc lpfc_enable_fc4_type=3" > /etc/modprobe.d/lpfc.conf

Make sure that the Broadcom adapter firmware has at least version 11.4.204.33. Also make sure that you have the current versions of nvme-cli, nvmetcli and the Kernel installed.

To enable a Fibre Channel port as an NVMe target, an additional module parameter needs to be configured: lpfc_enable_nvmet= COMMA_SEPARATED_WWPNS. Enter the WWPN with a leading 0x, for example lpfc_enable_nvmet=0x2000000055001122,0x2000000055003344. Only listed WWPNs will be configured for target mode. A Fibre Channel port can either be configured as target or as initiator.

17.4.3 Marvell

FC-NVMe is supported on QLE269x and QLE27xx adapters. FC-NVMe support is enabled by default in the Marvell® QLogic® QLA2xxx Fibre Channel driver.

To confirm NVMe is enabled, run the following command:

> cat /sys/module/qla2xxx/parameters/ql2xnvmeenable

A resulting 1 means NVMe is enabled, a 0 indicates it is disabled.

Next, ensure that the Marvell adapter firmware is at least version 8.08.204 by checking the output of the following command:

> cat /sys/class/scsi_host/host0/fw_version

Last, ensure that the latest versions available for SUSE Linux Enterprise Server of nvme-cli, QConvergeConsoleCLI, and the Kernel are installed. You may, for example, run

# zypper lu && zypper pchk

to check for updates and patches.

For more details on installation, please refer to the FC-NVMe sections in the following Marvell user guides:

17.5 More Information

For more details about the abilities of the nvme command, refer to nvme nvme-help.

The following links provide a basic introduction to NVMe and NVMe over Fabric: