SOC also stands for system-on-a-chip.
A switch-on-a-chip (SOC) is a network - typically a storage network - switch (a device that channels incoming data flow from any of multiple input ports to the output port appropriate for its destination) that is built into a single microchip (integrated circuit). Used with multiple storage disk drives (sometimes called "just a bunch of disks"), a switch is said to be able to improve latency (increase the speed at which data is moved) and to ensure "fairness" (access to all drives on some round-robin rather than on a fixed sequential basis). A user can also add a new storage device more easily to a switch than directly to a controller. One company, Vixel, also packages its switch-on-a-chip in alternative packages - as a blade (a module to be fitted in a specified kind of frame) and in a box. Presumably, the more compact microchip version could be designed into systems where space was a constraint. The switch-on-a-chip is said to be a possible alternative to a Fibre Channel network.