NAME

       nbdkit-client - how to mount NBD filesystems on a client machine

DESCRIPTION

       For NBD exports that contain filesystems there are several approaches to mounting them on
       a client machine.

       To ensure the nbd kernel module is loaded you may need to do:

        # echo nbd > /etc/modules-load.d/nbd.conf

       This will not take effect until you reboot, so also do:

        # modprobe nbd

   Easy mounting at boot time
       For simple setups the following method is the easiest way to get an NBD filesystem to
       mount at boot.  Create or edit /etc/rc.local or /etc/rc.d/rc.local:

        #!/bin/sh -
        nm-online
        modprobe nbd
        nbd-client server /dev/nbd0
        mount /dev/nbd0 /mnt

   Mounting using systemd mount points
       You can use systemd mount points to mount NBD filesystems at boot and/or on demand.

       Set up an nbdtab(5) mapping.  If /etc/nbdtab doesn't exist, then create it first.  Add
       this line:

        nbd0 server / bs=512,persist

       As a workaround for https://github.com/NetworkBlockDevice/nbd/issues/91 you must currently
       modify the nbd@.service file:

        # cp /usr/lib/systemd/system/nbd@.service /etc/systemd/system/
        # vi /etc/systemd/system/nbd@.service

       and edit or create these settings in the "[Service]" section:

        [Service]
        Type=oneshot
        RemainAfterExit=yes
        ExecStart=/usr/sbin/nbd-client %i
        ExecStop=/usr/sbin/nbd-client -d /dev/%i

       Finally create a systemd mount file called /etc/systemd/system/mnt.mount:

        [Unit]
        Requires=nbd@nbd0.service
        [Mount]
        What=/dev/nbd0
        Where=/mnt
        Type=ext4

       You can either reboot now or do:

        # systemctl start mnt.mount

       Other systemd services which need this mount point can depend on this mount unit.

LIMITATIONS

       Red Hat Enterprise Linux 8 enabled the "nbd.ko" Linux kernel module but only for Unix
       domain sockets (ie. local connections).  This means you cannot connect to an NBD server
       over a TCP network.  This also affects Linux distributions derived from RHEL like CentOS,
       Alma and others.

       This does not affect use of nbdkit as an NBD server, only the Linux kernel as an NBD
       client.  Userspace Linux clients such as libnbd(3) tools will work.

SEE ALSO

       nbdkit(1), nbdkit-loop(1), nbdkit-service(1), nbd-client(8), nbdtab(5), systemd(1),
       systemd.mount(5).

AUTHORS

       Richard W.M. Jones

COPYRIGHT

       Copyright Red Hat

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