Comment 32 for bug 1023755

psuedo script to reproduce outside of openstack/devstack:

*This omits the iscsi target creation/deletion steps.*

DATA_DIR=~/DATA
VOLUME_BACKING_FILE_SIZE=${VOLUME_BACKING_FILE_SIZE:-5130M}
VOLUME_GROUP=${VOLUME_GROUP:-stack-volumes}
VOLUME_BACKING_FILE=${VOLUME_BACKING_FILE:-$DATA_DIR/${VOLUME_GROUP}-backing-file}

if ! sudo vgs $VOLUME_GROUP; then
    VOLUME_BACKING_FILE=${VOLUME_BACKING_FILE:-$DATA_DIR/${VOLUME_GROUP}-backing-file}
    # Only create if the file doesn't already exists
    [[ -f $VOLUME_BACKING_FILE ]] || truncate -s $VOLUME_BACKING_FILE_SIZE $VOLUME_BACKING_FILE
    DEV=`sudo losetup -f --show $VOLUME_BACKING_FILE`
    # Only create if the loopback device doesn't contain $VOLUME_GROUP
    if ! sudo vgs $VOLUME_GROUP; then sudo vgcreate $VOLUME_GROUP $DEV; fi
fi

lvcreate -L 2G -n "test-vol" $VOLUME_GROUP
lvcreate -L 2G --name "test-snap" --snapshot "test-vol"

dd count=0 if=/dev/zero of=test-vol count= bs=1M iflag=direct oflag=direct