This object indicates the numerically lowest available
index within this entity, which may be used for the
value of etsysMirrorDestinationControlIndex in the creation
of a new entry in the etsysMirrorDestinationControlTable.
An index is considered available if the index value
falls within the range of 1 to (newLeaf with max dest groups)
and is not being used to index an existing entry in the
etsysMirrorDestinationControlTable contained within this entity.
A value of zero indicates that all of the entries in the
etsysMirrorDestinationControlTable are currently in use.
This value SHOULD only be considered a guideline for
management creation of etsysMirrorDestinationControlTable
entries, there is no requirement on management to create
entries based upon this index value.