Patent ID: 7568068

Claim:
A disk drive comprising: a rotatable recording disk for the storage of user data from a host computer; a controller for writing user data to and reading user data from the disk; and a cache connected to the controller for temporary storage of user data, the cache comprising nonvolatile memory having a plurality of cache lines for the storage of user data and volatile memory having a plurality of cache lines for the storage of user data and a cache line write (CLW) count field associated with each nonvolatile memory cache line for representing the number of times the associated nonvolatile memory cache line has been accessed; wherein the controller includes logic for executing method acts comprising: in response to a request from the host computer, searching the volatile memory to determine if the requested user data is stored in the nonvolatile memory; and when writing new user data to nonvolatile memory, first evicting the user data from a cache line having the smallest CLW count field value, and thereafter writing the new user data to said cache line having the smallest CLW count field value.