Installing FreeBSD 9.x Root on ZFS using GPT

1. Creating a bootable ZFS Filesystem

  1. Boot FreeBSD Install USB Memstick
  2. Choose LiveCD when asked
  3. Mount Root filesystem read-writeable to prevent further problems
     mount -rw /
  4. Create GPT Disk
     Fixit# gpart create -s gpt ad0


    • If the disk already contains a partitioning scheme, and this scheme would first need to be destroyed using:
     Fixit# gpart destroy ad0
  5. Create the boot, swap and zfs partitions
     Fixit# gpart add -s 64K -t freebsd-boot ad0
     Fixit# gpart add -s 4G -t freebsd-swap -l swap0 ad0
     Fixit# gpart add -t freebsd-zfs -l disk0 ad0

    This creates 3 partitions. The first partition will contains the gptzfsboot loader which will be able to load /boot/loader or /boot/zfsloader (9.0-CURRENT) from a ZFS partition. The second partition is a 4 GB swap partition. The third partition is dedicated to the ZFS zpool and uses the remaining space on the disk.


    1. While a ZFS Swap Volume can be used instead of the freebsd-swap partition, crash dumps can't be saved to the ZFS Swap Volume.

  6. Install the Protected MBR (pmbr) and gptzfsboot loader
     Fixit# gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ad0
    This may fail with an "operation not permitted" error message, since the kernel likes to protect critical parts of the disk. If this happens for you, run:
     Fixit# sysctl kern.geom.debugflags=0x10
  7. Load ZFS kernel module
     Fixit# kldload opensolaris.ko
     Fixit# kldload zfs.ko
  8. Create ZFS Pool zroot
     Fixit# zpool create zroot /dev/gpt/disk0
     Fixit# zpool set bootfs=zroot zroot


    • zroot is the name of the ZFS Pool, it could be anything (i.e. tank, data, ...)

2. Installing FreeBSD to the ZFS filesystem

  1. Create ZFS filesystem hierarchy

    The fletcher4 algorithm should be more robust than the fletcher2 algorithm.

     Fixit# zfs set checksum=fletcher4                                      zroot
     Fixit# zfs create -o compression=on    -o exec=on      -o setuid=off   zroot/tmp
     Fixit# chmod 1777 /zroot/tmp
     Fixit# zfs create                                                      zroot/usr
     Fixit# zfs create                                                      zroot/usr/home
     Fixit# cd /zroot ; ln -s /usr/home home
     Fixit# zfs create -o compression=lzjb                  -o setuid=off   zroot/usr/ports
     Fixit# zfs create -o compression=off   -o exec=off     -o setuid=off   zroot/usr/ports/distfiles
     Fixit# zfs create -o compression=off   -o exec=off     -o setuid=off   zroot/usr/ports/packages


    If you use nullfs or nfs to mount /usr/ports to different locations/servers, you will also need to nullfs/nfs mount /usr/ports/distfiles and/or /usr/ports/packages.

     Fixit# zfs create -o compression=lzjb  -o exec=off     -o setuid=off   zroot/usr/src
     Fixit# zfs create                                                      zroot/var
     Fixit# zfs create                      -o exec=off     -o setuid=off   zroot/var/db
     Fixit# zfs create -o compression=lzjb  -o exec=on      -o setuid=off   zroot/var/db/pkg
     Fixit# zfs create                      -o exec=off     -o setuid=off   zroot/var/empty
     Fixit# zfs create -o compression=lzjb  -o exec=off     -o setuid=off   zroot/var/log
     Fixit# zfs create -o compression=lzjb  -o exec=on      -o setuid=off   zroot/var/tmp
     Fixit# chmod 1777 /zroot/var/tmp


    1. Compression may be set to on, off, lzjb, gzip, gzip-N (where N is an integer from 1 (fastest) to 9 (best compresion ratio. gzip is equivalent to gzip-6).
    2. Compression will cause some latency when accessing files on the ZFS filesystems. Use compression on ZFS filesystems which will not be accessed that often.

  2. Install FreeBSD to zroot using bsdinstall
    1. When asked about Partitioning choose "shell"
    2. Mount filesystem to /mnt
        zfs set mountpoint=/mnt zroot
        zfs set mountpoint=/mnt/tmp zroot/tmp
        zfs set mountpoint=/mnt/usr zroot/usr
        zfs set mountpoint=/mnt/var zroot/var
        zfs mount -a
    3. Exit shell and go back to bsdinstall to let it install your FreeBSD system
  3. Make /var/empty readonly
     Fixit# zfs set readonly=on zroot/var/empty
  4. chroot into /zroot
     Fixit# chroot /mnt
  5. Create /etc/rc.conf
     Fixit# echo 'zfs_enable="YES"' >> /etc/rc.conf
  6. Create /boot/loader.conf
     Fixit# echo 'zfs_load="YES"' > /boot/loader.conf
     Fixit# echo 'vfs.root.mountfrom="zfs:zroot"' >> /boot/loader.conf
  7. Exit from chroot
     Fixit# exit
  8. Install zpool.cache to the ZFS filesystem
     Fixit# cp /boot/zfs/zpool.cache /boot/zfs/zpool.cache

3. Finish install

  1. Create /etc/fstab
     Fixit# cat << EOF > /mnt/etc/fstab
     # Device                       Mountpoint              FStype  Options         Dump    Pass#
     /dev/gpt/swap0                 none                    swap    sw              0       0
  2. Unmount all zfs filesystems
     Fixit# zfs unmount -a
  3. Change mount points for zroot pool
     Fixit# zfs set mountpoint=legacy zroot
     Fixit# zfs set mountpoint=/tmp zroot/tmp
     Fixit# zfs set mountpoint=/usr zroot/usr
     Fixit# zfs set mountpoint=/var zroot/var
  4. Exit Fixit mode, and then bsdinstall. Remove the FreeBSD install DVD/Memstick and the system will boot using the ZFS root.


BernhardFroehlich/ZFS (last edited 2018-03-31T08:29:01+0000 by MarkLinimon)