Comment 25 for bug 533493

This is an excerpt of what I use for backups using lvm snapshots... works fine on FC16.

We retain a few GB of free space in the LVM storage for the snapshot,
which generally suffices on most systems unless there is a lot
of updates happening during backups, which is rare on the systems
we use this on.

--
DTYPE=$1
# NB: level contains level and 'u' option (eg: 0u)
LEVEL=$2
TAPE=$3
FS=$4
RHOST=$5

case "${TAPE}${RHOST}" in
--)
        # dumping to stdout
        RTAPE="-"
        ;;
*)
        # using rsh/rmt(8)
        RTAPE="${RHOST}:${TAPE}"
        ;;
esac

LVCREATE=""
if [ -x /sbin/lvcreate ]
then
        LVCREATE="/sbin/lvcreate"
        LVREMOVE="/sbin/lvremove"
        LVDISPLAY="/sbin/lvdisplay"
elif [ -x /usr/sbin/lvcreate ]
then
        LVCREATE="/usr/sbin/lvcreate"
        LVREMOVE="/usr/sbin/lvremove"
        LVDISPLAY="/usr/sbin/lvdisplay"
fi

if [ "`df $FS | grep /dev/mapper`" -a "$LVCREATE" != "" ] ; then
        DUMPDEV=`df $FS |grep mapper | cut -d/ -f4 | cut -d' ' -f1 | tr - /`
        VOL=`echo $DUMPDEV | cut -d/ -f1`
        SNAPVOL=`echo $DUMPDEV | cut -d / -f2`-snap
        SNAPVOL2=`echo $DUMPDEV | cut -d / -f2`--snap
        SNAPDEV=/dev/$VOL/$SNAPVOL
        SNAPRDEV=/dev/mapper/$VOL-$SNAPVOL2
        echo DUMPDEV=$DUMPDEV 1>&2
        echo VOL=$VOL 1>&2
        echo SNAPVOL=$SNAPVOL 1>&2
        echo SNAPVOL2=$SNAPVOL2 1>&2
        echo SNAPDEV=$SNAPDEV 1>&2
        echo SNAPRDEV=$SNAPRDEV 1>&2

        # cleanup from last backup
        $LVREMOVE -f $SNAPDEV >/dev/null 2>&1

        echo `date` starting snapshot 1>&2
        $LVCREATE -l 100%FREE -s -n $SNAPVOL /dev/$DUMPDEV 1>&2
        echo `date` starting backup 1>&2

        dump "${LEVEL}bfL" 32 "$RTAPE" "$FS" $SNAPRDEV

        # workaround FC16 bug; delay before clearing
        sleep 5

        echo `date` clearing snapshot 1>&2
        $LVREMOVE -f $SNAPDEV 1>&2

        # workaround FC16 bug; do it again if needed
        for i in 1 2 3 4 5
        do
                $LVDISPLAY | grep $SNAPDEV >/dev/null
                if [ $? = 0 ]
                then
                        # its still there!
                        sleep 5
                        echo `date` clearing snapshot again 1>&2
                        $LVREMOVE -f $SNAPDEV 1>&2
                else
                        break
                fi
        done
        $LVDISPLAY | grep $SNAPDEV >/dev/null
        if [ $? = 0 ]
        then
                echo `date` gave up clearing snapshot - manual intervention required 1>&2
                STATUS=1
        fi

exit $STATUS