The size of L1 cache should be equal to the amount of the average working data set.
There are no default or maximum values for RAM cache as such. The maximum size that can be assigned for StarWind RAM cache is limited by the available RAM to the system; also, you need to make sure that other applications running will have enough of RAM for their operations.
Additionally, the total amount of L1 cache assigned influences the time required for system shutdown so overprovisioning of the L1 cache amount can cause StarWind service interruption and the loss of cached data. The minimum size assigned for RAM cache in either write-back or write-through mode is 1MB. However, StarWind recommends assigning a StarWind RAM cache size that matches the size of the working data set.