FreeBSD GEOM mirror

GEOM mirror Approach 1: Whole Disk, Acceptable, Less Flexible

The following is a step-by-step command list for remotely converting a production FreeBSD 5.3-STABLE system from a single-disk (ad0) to a two-disk (ad0 & ad1) GEOM mirror (gm0) based setup without the need for console access or Fixit/LiveFS CDROM. The assumption is that the two disks are EQUAL in size or that the second disk is a little bit SMALLER than the first one.

# make sure the second disk is treated as a really fresh one
# (not really necessary, but makes procedure more deterministically 😉
dd if=/dev/zero of=/dev/ad1 bs=512 count=79

# place a GEOM mirror label onto second disk
# (actually on the last block of the disk)
gmirror label -v -n -b round-robin gm0 /dev/ad1

# activate GEOM mirror kernel layer
# (makes the /dev/mirror/gm0 device available)
gmirror load

# place a PC MBR onto the second disk
# (with a single FreeBSD slice /dev/mirror/gm0s1 covering the whole disk)
fdisk -v -B -I /dev/mirror/gm0

# place a BSD disklabel onto /dev/mirror/gm0s1
# (ATTENTION: in FreeBSD 5-STABLE before 14-Jan-2005 the
# /dev/mirror/gm0s1 device has to be specified as just "mirror/gm0s1" or
# the bsdlabel(8) will use the incorrect GEOM name "gm0s1" instead!)
# (NOTICE: figure out what partitions you want with "bsdlabel /dev/ad0" before)
# (NOTICE: start "a" partition at offset 16, "c" partition at offset 0)
bsdlabel -w -B /dev/mirror/gm0s1 # initialize
bsdlabel -e /dev/mirror/gm0s1    # create custom partitions

# manually copy filesystem data from first to to second disk
# (same procedure for partitions "g", etc)
newfs -U /dev/mirror/gm0s1a
mount /dev/mirror/gm0s1a /mnt
dump -L -0 -f- / | (cd /mnt; restore -r -v -f-)
newfs -U /dev/mirror/gm0s1d
mount /dev/mirror/gm0s1d /mnt/var
dump -L -0 -f- /var | (cd /mnt/var; restore -r -v -f-)
newfs -U /dev/mirror/gm0s1e
mount /dev/mirror/gm0s1e /mnt/usr
dump -L -0 -f- /usr | (cd /mnt/usr; restore -r -v -f-)

# adjust new system configuration for GEOM mirror based setup
cp -p /mnt/etc/fstab /mnt/etc/fstab.orig
sed -e 's/dev\/ad0/dev\/mirror\/gm0/g' </mnt/etc/fstab.orig >/mnt/etc/fstab
echo 'swapoff="YES"' >>/mnt/etc/rc.conf # for 5.3-RELEASE only
echo 'geom_mirror_load="YES"' >>/mnt/boot/loader.conf

# instruct boot stage 2 loader on first disk to boot
# with the boot stage 3 loader from the second disk
# (mainly because BIOS might not allow easy booting from second ATA disk
# or at least requires manual intervention on the console)
echo "1:ad(1,a)/boot/loader" >/boot.config

# reboot system
# (for running system with GEOM mirror on second disk)
shutdown -r now

# make sure the first disk is treated as a really fresh one
# (also not really necessary, but makes procedure more deterministically 😉
dd if=/dev/zero of=/dev/ad0 bs=512 count=79

# switch GEOM mirror to auto-synchronization and add first disk
# (first disk is now immediately synchronized with the second disk content)
gmirror configure -a gm0
gmirror insert gm0 /dev/ad0

# wait for the GEOM mirror synchronization to complete
sh -c 'while [ ".`gmirror list | grep SYNCHRONIZING`" != . ]; do sleep 1; done'

# reboot into the final two-disk GEOM mirror setup
# (now actually boots with the MBR and boot stages on first disk
# as it was synchronized from second disk)
shutdown -r now
    

GEOM mirror Approach 2: Single Slice, Preferred, More Flexible

The following is a step-by-step command list for remotely converting a production FreeBSD 5.3-STABLE system from a single-disk/single-slice (ad0s1) to a two-disk/single-slice (ad0s1 & ad1s1) GEOM mirror (gm0s1) based setup without the need for console access or Fixit/LiveFS CDROM:

# make sure the second disk is treated as a really fresh one
# (not really necessary, but makes procedure more deterministically 😉
dd if=/dev/zero of=/dev/ad1 bs=512 count=79

# place a PC MBR onto the second disk
# (with a single FreeBSD slice /dev/mirror/gm0s1 as large as the /dev/ad0s1)
# either automatically if sizes fit...
fdisk -v -B -I /dev/ad1
# ...or manually to make sure the sizes fit:
size=`fdisk ad0 | grep ', size ' | head -1 | sed -e 's;^.*size \([0-9]*\).*$;\1;'`
# ...and reduce the size by one block because ad0 and ad0s1 else would
# share the same last sector which could lead to ad0 be recognized as
# the GEOM provider instead of ad0s1. Alternatively, you can keep ad0
# and ad0s1 of the same size and hard-code the ad0s1 GEOM provider by
# adding the -h option to the "gmirror label" command below.
size=`expr $size - 1`
(echo "p 1 165 63 $size"; echo "a 1") | fdisk -v -f- -i /dev/ad1

# place a GEOM mirror label onto first slice of second disk
# (actually on the last block of the disk slice)
gmirror label -v -n -b round-robin gm0s1 /dev/ad1s1

# activate GEOM mirror kernel layer
# (makes the /dev/mirror/gm0s1 device available)
gmirror load

# place a BSD disklabel onto /dev/mirror/gm0s1
# (ATTENTION: in FreeBSD 5-STABLE before 14-Jan-2005 the
# /dev/mirror/gm0s1 device has to be specified as just "mirror/gm0s1" or
# the bsdlabel(8) will use the incorrect GEOM name "gm0s1" instead!)
# (NOTICE: figure out what partitions you want with "bsdlabel /dev/ad0" before)
# (NOTICE: start "a" partition at offset 16, "c" partition at offset 0)
bsdlabel -w -B /dev/mirror/gm0s1 # initialize
bsdlabel -e /dev/mirror/gm0s1    # create custom partitions

# manually copy filesystem data from first to to second disk
# (same procedure for partitions "g", etc)
newfs -U /dev/mirror/gm0s1a
mount /dev/mirror/gm0s1a /mnt
dump -L -0 -f- / | (cd /mnt; restore -r -v -f-)
newfs -U /dev/mirror/gm0s1d
mount /dev/mirror/gm0s1d /mnt/var
dump -L -0 -f- /var | (cd /mnt/var; restore -r -v -f-)
newfs -U /dev/mirror/gm0s1e
mount /dev/mirror/gm0s1e /mnt/usr
dump -L -0 -f- /usr | (cd /mnt/usr; restore -r -v -f-)

# adjust new system configuration for GEOM mirror based setup
cp -p /mnt/etc/fstab /mnt/etc/fstab.orig
sed -e 's/dev\/ad0s1/dev\/mirror\/gm0s1/g' </mnt/etc/fstab.orig >/mnt/etc/fstab
echo 'swapoff="YES"' >>/mnt/etc/rc.conf # for 5.3-RELEASE only
echo 'geom_mirror_load="YES"' >>/mnt/boot/loader.conf

# instruct boot stage 2 loader on first disk to boot
# with the boot stage 3 loader from the second disk
# (mainly because BIOS might not allow easy booting from second ATA disk
# or at least requires manual intervention on the console)
echo "1:ad(1,a)/boot/loader" >/boot.config

# reboot system
# (for running system with GEOM mirror on second disk)
shutdown -r now

# make sure the first disk is treated as a really fresh one
# (also not really necessary, but makes procedure more deterministically 😉
dd if=/dev/zero of=/dev/ad0 bs=512 count=79

# place a new PC MBR onto the first disk
# (with a single FreeBSD slice /dev/ad0s1 _exactly_ as large as the /dev/ad1s1)
size=`fdisk ad1 | grep ', size ' | head -1 | sed -e 's;^.*size \([0-9]*\).*$;\1;'`
(echo "p 1 165 63 $size"; echo "a 1") | fdisk -v -B -f- -i /dev/ad0

# switch GEOM mirror to auto-synchronization and add first disk
# (first disk is now immediately synchronized with the second disk content)
gmirror configure -a gm0s1
gmirror insert gm0s1 /dev/ad0s1

# wait for the GEOM mirror synchronization to complete
sh -c 'while [ ".`gmirror list | grep SYNCHRONIZING`" != . ]; do sleep 1; done'

# reboot into the final two-disk GEOM mirror setup
# (now actually boots with the MBR and boot stages on first disk
# as it was synchronized from second disk)
shutdown -r now