Disk Setup On FreeBSD

Last updated 2013-06-24

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Setting up disks with FreeBSD.

The New Standard: GPT

GPT is the newer and more versatile partition method. Use it unless compatibility with the old standard MBR is required.

The disk device being set up here is da0.

Create a GPT partition scheme on /dev/da0. /dev/ is implied:

# gpart create -s gpt da0
da0 created

Create a boot partition to hold the loader, size of 512K. Give it a GPT label of gpboot, which will show up in /dev/gpt when the device is discovered:

# gpart add -t freebsd-boot -l gpboot -b 40 -s 512K da0
da0p1 added

Install the GPT bootcode into the boot partition:

# gpart bootcode -b /boot/pmbr -p /boot/gptboot -i 1 da0
bootcode written to da0

Create a partition for /. It should start at the 1M boundary for proper sector alignment on 4K sector drives or SSDs. This is compatible with GPT drive layout for many other systems. Give it a GPT label of gprootfs.

# gpart add -t freebsd-ufs -l gprootfs -b 1M -s 2G da0
da0p2 added

Create partitions for swap, /var, /tmp, /usr. Leaving the -s size option off the last uses the rest of the disk. As long as these are even sizes in M or G, the alignment will remain correct.

# gpart add -t freebsd-swap -l gpswap -s 512M da0
da0p3 added
# gpart add -t freebsd-ufs  -l gpvarfs -s 1G da0
da0p4 added
# gpart add -t freebsd-ufs  -l gptmpfs -s 256M da0
da0p5 added
# gpart add -t freebsd-ufs  -l gpusrfs         da0
da0p6 added
# gpart show -l da0
=>      34  19640813  da0  GPT  (9.4G)
        34         6       - free -  (3.0k)
        40      1024    1  gpboot  (512k)
      1064       984       - free -  (492k)
      2048   4194304    2  gprootfs  (2.0G)
   4196352   1048576    3  gpswap  (512M)
   5244928   2097152    4  gpvarfs  (1.0G)
   7342080    524288    5  gptmpfs  (256M)
   7866368  11774479    6  gpusrfs  (5.6G)

If there’s a need or desire to redo this partition layout, gpart(8) won’t destroy the "geom" until all of the partitions in it have been deleted:

# gpart delete -i 1 da0
da0p1 deleted
# gpart delete -i 2 da0
da0p2 deleted
# gpart delete -i 3 da0
da0p3 deleted
# gpart delete -i 4 da0
da0p4 deleted
# gpart delete -i 5 da0
da0p5 deleted
# gpart delete -i 6 da0
da0p6 deleted
# gpart destroy da0

Later versions of gpart(8) have a -F (force) option for destroy that makes things quicker but sort of blunt and stabby at the same time:

# gpart destroy -F da0
da0 destroyed

Format the new filesystems, enabling soft updates for performance. Filesystem labels can be added here, but probably should not be the same as the GPT labels already assigned.

# newfs -U /dev/gpt/gprootfs
# newfs -U /dev/gpt/gpvarfs
# newfs -U /dev/gpt/gptmpfs
# newfs -U /dev/gpt/gpusrfs

See http://www.freebsd.org/doc/en_US.ISO8859-1/books/faq/disks.html#SAFE-SOFTUPDATES for more information on using soft updates on the root filesystem.

Restore data. Labels are used in the mount command here because they’re easier to identify, but device names like /dev/da0p2 will work.

# mount /dev/gpt/gprootfs /mnt
# (cd /mnt && gzcat root.dump.gz | restore -ruf -)
# umount /mnt

Repeat for /var, /tmp, /usr.

Modify /etc/fstab:

# Device                Mountpoint      FStype  Options         Dump    Pass#
/dev/gpt/gpswap         none            swap    sw              0       0
/dev/gpt/gprootfs       /               ufs     rw              1       1
/dev/gpt/gptmpfs        /tmp            ufs     rw              2       2
/dev/gpt/gpusrfs        /usr            ufs     rw              2       2
/dev/gpt/gpvarfs        /var            ufs     rw              2       2

Done!

The Old Standard: MBR

Usually the GPT setup above is the better choice. This older method creates an MBR partition table, which can be useful for backwards compatibility.

Again, we’re setting up da0.

If remnants of a GPT partitioning scheme are still present on the disk, it will be seen instead of the MBR. Destroying that old partitioning scheme before creating the new MBR is important.

# gpart destroy -F da0

Older versions of gpart(8) did not have -F to easily remove old partition schemes without deleting all partitions first. An alternate way to remove GPT tables is using dd(1) to overwrite the GPT primary table at the start of the disk:

# dd if=/dev/zero of=/dev/da0 bs=512 count=34

Removing the secondary or backup GPT table at the end of the disk requires a little calculation. Use diskinfo(8) to get the number of blocks, subtract the 34-block length of the standard table, and write from there to the end of the disk. In this example, the disk has 60030432 blocks. Subtracting 34 from that gives 60030398 as the starting location, and dd(1) will write from there to the end of the disk.

# diskinfo -v da0
        512             # sectorsize
        30735581184     # mediasize in bytes (28G)
        60030432        # mediasize in sectors
        0               # stripesize
        0               # stripeoffset
        3736            # Cylinders according to firmware.
        255             # Heads according to firmware.
        63              # Sectors according to firmware.
        560482EC2222    # Disk ident.
# echo '60030432 - 34' | bc
60030398
# dd if=/dev/zero of=/dev/da0 bs=512 seek=60030398

Create the MBR partitioning scheme:

# gpart create -s mbr da0

Make it bootable by installing bootcode.

# gpart bootcode -b /boot/mbr da0

Create an MBR partition. FreeBSD calls these "slices". Set it active so the system will boot from it.

# gpart add -t freebsd da0
# gpart set -a active -i 1 da0

Inside the FreeBSD slice, create a bsdlabel partitioning scheme. Bootcode is needed here also.

# gpart create -s bsd da0s1
# gpart bootcode -b /boot/boot da0s1

Create the FreeBSD "partitions" inside the slice.

# gpart add -t freebsd-ufs  -a 4k -s 2g   da0s1
# gpart add -t freebsd-swap -a 4k -s 512m da0s1
# gpart add -t freebsd-ufs  -a 4k -s 1g   da0s1
# gpart add -t freebsd-ufs  -a 4k -s 256m da0s1
# gpart add -t freebsd-ufs  -a 4k         da0s1

Format and label the filesystems before they are mounted, enabling soft updates for better performance:

# glabel label swap /dev/da0s1b
# newfs -L rootfs -U /dev/da0s1a
# newfs -L varfs  -U /dev/da0s1d
# newfs -L tmpfs  -U /dev/da0s1e
# newfs -L usrfs  -U /dev/da0s1f

See http://www.freebsd.org/doc/en_US.ISO8859-1/books/faq/disks.html#SAFE-SOFTUPDATES for more information on using soft updates on the root filesystem.

Restore data to the new filesystems:

# mount /dev/da0s1a /mnt
# gzcat root.dump.gz | (cd /mnt && restore -rf -)
# umount /mnt

Repeat for /var, /tmp, /usr.

Modify /etc/fstab:

# Device                Mountpoint      FStype  Options         Dump    Pass#
/dev/label/swap         none            swap    sw              0       0
/dev/ufs/rootfs         /               ufs     rw              1       1
/dev/ufs/tmpfs          /tmp            ufs     rw              2       2
/dev/ufs/usrfs          /usr            ufs     rw              2       2
/dev/ufs/varfs          /var            ufs     rw              2       2

Done!