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.\"
.IX Title "nbdkit-client 1"
.TH nbdkit-client 1 2024-04-21 nbdkit-1.38.1 NBDKIT
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH NAME
nbdkit\-client \- how to mount NBD filesystems on a client machine
.SH DESCRIPTION
.IX Header "DESCRIPTION"
For NBD exports that contain filesystems there are several approaches
to mounting them on a client machine.
.PP
To ensure the nbd kernel module is loaded you may need to do:
.PP
.Vb 1
\& # echo nbd > /etc/modules\-load.d/nbd.conf
.Ve
.PP
This will not take effect until you reboot, so also do:
.PP
.Vb 1
\& # modprobe nbd
.Ve
.SS "Easy mounting at boot time"
.IX Subsection "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 \fI/etc/rc.local\fR or
\&\fI/etc/rc.d/rc.local\fR:
.PP
.Vb 5
\& #!/bin/sh \-
\& nm\-online
\& modprobe nbd
\& nbd\-client server /dev/nbd0
\& mount /dev/nbd0 /mnt
.Ve
.SS "Mounting using systemd mount points"
.IX Subsection "Mounting using systemd mount points"
You can use systemd mount points to mount NBD filesystems at boot
and/or on demand.
.PP
Set up an \fBnbdtab\fR\|(5) mapping.  If \fI/etc/nbdtab\fR doesn't exist, then
create it first.  Add this line:
.PP
.Vb 1
\& nbd0 server / bs=512,persist
.Ve
.PP
As a workaround for
https://github.com/NetworkBlockDevice/nbd/issues/91 you must
currently modify the \fInbd@.service\fR file:
.PP
.Vb 2
\& # cp /usr/lib/systemd/system/nbd@.service /etc/systemd/system/
\& # vi /etc/systemd/system/nbd@.service
.Ve
.PP
and edit or create these settings in the \f(CW\*(C`[Service]\*(C'\fR section:
.PP
.Vb 5
\& [Service]
\& Type=oneshot
\& RemainAfterExit=yes
\& ExecStart=/usr/sbin/nbd\-client %i
\& ExecStop=/usr/sbin/nbd\-client \-d /dev/%i
.Ve
.PP
Finally create a systemd mount file called
\&\fI/etc/systemd/system/mnt.mount\fR:
.PP
.Vb 6
\& [Unit]
\& Requires=nbd@nbd0.service
\& [Mount]
\& What=/dev/nbd0
\& Where=/mnt
\& Type=ext4
.Ve
.PP
You can either reboot now or do:
.PP
.Vb 1
\& # systemctl start mnt.mount
.Ve
.PP
Other systemd services which need this mount point can depend on this
mount unit.
.SH LIMITATIONS
.IX Header "LIMITATIONS"
Red Hat Enterprise Linux 8 enabled the \f(CW\*(C`nbd.ko\*(C'\fR 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.
.PP
This does not affect use of nbdkit as an NBD server, only the Linux
kernel as an NBD client.  Userspace Linux clients such as \fBlibnbd\fR\|(3)
tools will work.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBnbdkit\fR\|(1),
\&\fBnbdkit\-loop\fR\|(1),
\&\fBnbdkit\-service\fR\|(1),
\&\fBnbd\-client\fR\|(8),
\&\fBnbdtab\fR\|(5),
\&\fBsystemd\fR\|(1),
\&\fBsystemd.mount\fR\|(5).
.SH AUTHORS
.IX Header "AUTHORS"
Richard W.M. Jones
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright Red Hat
.SH LICENSE
.IX Header "LICENSE"
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
.IP \(bu 4
Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
.IP \(bu 4
Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
.IP \(bu 4
Neither the name of Red Hat nor the names of its contributors may be
used to endorse or promote products derived from this software without
specific prior written permission.
.PP
THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.