Since 2.6, hbal crashes when used on a cluster where no
LVM storage is enabled at all. The problem is that it
always queries for fields that only sometimes make
sense for certain types of storage. This patch will
make it fall-back to a default value if those fields
are not returned by a query. This way it will simply
disregard the space information in its calculation
which is the best we can do in this situation, because
not all storage types support space reporting.

Signed-off-by: Helga Velroyen <helgav@google.com>
Reviewed-by: Klaus Aehlig <aehlig@google.com>