Installing FreeBSD 10 to ZFS with a script

Well, partially scripted, that is.

For installing large numbers of identical machines, proceed directly to the PC-BSD installer. It’s easy to configure, very reliable, and generally just rocks. If you’re accustomed to automatic installers like Kickstart, you’ll find the PC-BSD installer trivially easy.

I frequently have to install non-identical machines for special purposes, such as testing or unique file stores or EDI. Most of these are virtual machines. It seems that ZFS filesystems compress really really well, simplifying backing up the VMs.

And there, the FreeBSD 10 installer’s ZFS features don’t quite cut it. The installer lets you create a single large ZFS without leaving the GUI. I want a more complicated ZFS setup, based on the FreeBSD Root on ZFS wiki page. This process involves a whole lot of typing. I normally install servers when I’m too brain dead to do any real work, so I need to minimize the opportunity for errors.

Fortunately, you can script all the disk and ZFS setup. Here’s my script. If it looks familiar, well, it should: it’s ripped raw and bleeding from the wiki instructions and wrapped up with /bin/sh -x. (I use -x because I want to see how the script runs.)

#!/bin/sh -x

#Auto-divides a ZFS install.
#ZFS permissions stolen from

#disk device name
#parameters for your zpool type
#your pool name
#swap space

#we're installing
sysctl kern.geom.debugflags=0x10

gpart destroy -F vtbd0
gpart create -s gpt vtbd0
gpart add -s 222 -a 4k -t freebsd-boot -l boot0 vtbd0

gpart add -s 1g -a 4k -t freebsd-swap -l swap0 vtbd0
gpart add -a 4k -t freebsd-zfs -l disk0 vtbd0
gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 vtbd0
gnop create -S 4096 /dev/gpt/disk0

kldload zfs
zpool create -f -o altroot=/mnt -O canmount=off -m none zroot /dev/gpt/disk0.nop

zfs set checksum=fletcher4 zroot
zfs set atime=off zroot

zfs create -o mountpoint=none zroot/ROOT
zfs create -o mountpoint=/ zroot/ROOT/default
zfs create -o mountpoint=/tmp -o compression=lzjb -o setuid=off zroot/tmp
chmod 1777 /mnt/tmp

zfs create -o mountpoint=/usr zroot/usr
zfs create zroot/usr/local

zfs create -o mountpoint=/home -o setuid=off zroot/home
zfs create -o compression=lzjb -o setuid=off zroot/usr/ports
zfs create -o compression=off -o exec=off -o setuid=off zroot/usr/ports/distfiles
zfs create -o compression=off -o exec=off -o setuid=off zroot/usr/ports/packages

zfs create -o compression=lzjb -o exec=off -o setuid=off zroot/usr/src
zfs create zroot/usr/obj

zfs create -o mountpoint=/var zroot/var
zfs create -o compression=lzjb -o exec=off -o setuid=off zroot/var/crash
zfs create -o exec=off -o setuid=off zroot/var/db
zfs create -o compression=lzjb -o exec=on -o setuid=off zroot/var/db/pkg
zfs create -o exec=off -o setuid=off zroot/var/empty
zfs create -o compression=lzjb -o exec=off -o setuid=off zroot/var/log
zfs create -o compression=gzip -o exec=off -o setuid=off zroot/var/mail
zfs create -o exec=off -o setuid=off zroot/var/run
zfs create -o compression=lzjb -o exec=on -o setuid=off zroot/var/tmp
chmod 1777 /mnt/var/tmp
zpool set bootfs=zroot/ROOT/default zroot

cat << EOF > /tmp/bsdinstall_etc/fstab
/dev/gpt/swap0 none swap sw 0 0


How do I use this?

When the installer asks me how I want to partition the disk, I exit to the shell, configure the network, and get the script onto the target system.

# dhclient vtnet0
# cd /tmp
# fetch
# chmod 755
# ./

Sit back and watch it run. When the script finishes, exit from the shell and let the installer unpack the files. When you’re offered a shell to perform post-install configuration, take it and run the post-install ZFS setup commands.

# mount -t devfs devfs /dev
# echo 'zfs_enable="YES"' >> /etc/rc.conf
# echo 'zfs_load="YES"' >> /boot/loader.conf
# zfs set readonly=on zroot/var/empty

Reboot into your fine-grained ZFS filesystem installation.

To use this script yourself, you’ll need to check the disk device name and the type of zpool you want to create. But this will hopefully get you started.

I would really like to see the default FreeBSD installer create finer grained ZFS filesystems. I’m told that day is coming.

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