Abstract: Embodiments of the invention describe flexible (i.e., elastic) data center architectures capable of meeting exascale, while maintaining low latency and using reasonable sizes of electronic packet switches, through the use of optical circuit switches such as optical time, wavelength, waveband and space circuit switching technologies. This flexible architecture enables the reconfigurability of the interconnectivity of servers and storage devices within a data center to respond to the number, size, type and duration of the various applications being requested at any given point in time.