  Data backup in data center networks (DCNs) is critical to minimize the data
loss under disaster. This paper considers the cost-efficient data backup for
DCNs against a disaster with $\varepsilon$ early warning time. Given
geo-distributed DCNs and such a $\varepsilon$-time early warning disaster, we
investigate the issue of how to back up the data in DCN nodes under risk to
other safe DCN nodes within the $\varepsilon$ early warning time constraint,
which is significant because it is an emergency data protection scheme against
a predictable disaster and also help DCN operators to build a complete backup
scheme, i.e., regular backup and emergency backup. Specifically, an Integer
Linear Program (ILP)-based theoretical framework is proposed to identify the
optimal selections of backup DCN nodes and data transmission paths, such that
the overall data backup cost is minimized. Extensive numerical results are also
provided to illustrate the proposed framework for DCN data backup.
