1. A method for use in sizing volatile memory (VM) cache based on flash-based cache usage, the method comprising: receiving a user selection for a flash-based cache; based on the selection, providing, by a flash based cache driver, configuration and sizing factors to VM cache size determination logic; producing, by the VM cache size determination logic, a requested VM cache size, wherein producing the requested VM cache size comprises calculating a size of the flash-based cache based on the configuration and sizing factors, further wherein producing the requested VM cache size is dependent on the size of the flash-based cache and a ratio of VM cache required per unit of flash-based cache storage; and based on the requested VM cache size, causing, via VM cache resizing logic, the VM cache to be resized to the requested VM cache size.