In allocating an area of a cache memory to each storage unit, proper allocation of the cache memory is made to each storage unit. If the amount of write-after data becomes equal to or more than a threshold value, an allocation limit is set to each disk unit. If CPU issues a data write request requiring...http://www.google.com/patents/US6148367?utm_source=gb-gplus-sharePatent US6148367 - Controller limiting modification of cache based upon amount of dirty lines in the cache
