All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. 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.
THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 THE AUTHORS 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.
$FreeBSD: stable/11/stand/i386/zfsboot/zfsboot.8 344399 2019-02-20 23:55:35Z kevans $
.Dd March 27, 2018 .Dt ZFSBOOT 8 .Os .Sh NAME .Nm zfsboot .Nd bootcode for ZFS on BIOS-based computers .Sh DESCRIPTION .Nm is used on BIOS-based computers to boot from a filesystem in a ZFS pool. .Nm is installed in two parts on a disk or a partition used by a ZFS pool. The first part, a single-sector starter boot block, is installed at the beginning of the disk or partition. The second part, a main boot block, is installed at a special offset within the disk or partition. Both areas are reserved by the ZFS on-disk specification for boot use. If .Nm is installed in a partition, then that partition should be made bootable using appropriate configuration and boot blocks described in .Xr boot 8 . .Sh BOOTING The .Nm boot process is very similar to that of .Xr gptzfsboot 8 . One significant difference is that .Nm does not currently support the GPT partitioning scheme. Thus only whole disks and MBR partitions, traditionally referred to as slices, are probed for ZFS disk labels. See the BUGS section in .Xr gptzfsboot 8 for some limitations of the MBR scheme support. .Sh USAGE .Nm supports all the same prompt and configuration file arguments as .Xr gptzfsboot 8 . .Sh FILES l -tag -width /boot/zfsboot -compact t Pa /boot/zfsboot boot code binary t Pa /boot.config parameters for the boot block
q optional t Pa /boot/config alternative parameters for the boot block
q optional .El .Sh EXAMPLES .Nm is typically installed using .Xr dd 1 . To install .Nm on the
a ada0 drive: d -literal -offset indent dd if=/boot/zfsboot of=/dev/ada0 count=1 dd if=/boot/zfsboot of=/dev/ada0 iseek=1 oseek=1024 .Ed
p If the drive is currently in use, the GEOM safety will prevent writes and must be disabled before running the above commands: d -literal -offset indent sysctl kern.geom.debugflags=0x10 .Ed
p .Nm can also be installed in an MBR slice: d -literal -offset indent gpart create -s mbr ada0 gpart add -t freebsd ada0 gpart bootcode -b /boot/boot0 ada0 gpart set -a active -i 1 ada0 dd if=/dev/zero of=/dev/ada0s1 count=2 dd if=/boot/zfsboot of=/dev/ada0s1 count=1 dd if=/boot/zfsboot of=/dev/ada0s1 iseek=1 oseek=1024 .Ed
p Note that commands to create and populate a pool are not shown in the example above. .Sh SEE ALSO .Xr dd 1 , .Xr boot.config 5 , .Xr boot 8 , .Xr gptzfsboot 8 , .Xr loader 8 , .Xr zpool 8 .Sh HISTORY .Nm appeared in FreeBSD 7.3. .Sh AUTHORS This manual page was written by .An Andriy Gapon Aq avg@FreeBSD.org . .Sh BUGS Installing .Nm with .Xr dd 1 is a hack. ZFS needs a command to properly install .Nm onto a ZFS-controlled disk or partition.