Hard disk drive with optional cache memory

Abstract

A computer system includes a hard disk drive and an interface for optionally operationally connecting a cache memory for the hard disk drive, via a mechanism such as a system bus that is separate from the hard disk drive or directly to a controller of the hard disk drive. A hard disk drive of the present invention includes a nonvolatile medium for storing data, a controller for reading and writing the data and an interface for optionally operationally connecting to the controller a cache memory for the nonvolatile medium. Whether data are cached depends on whether the cache memory is present. Computer systems of the present invention are configured with or without cache memories, depending on customer requirements.

1 . A computer system comprising: 
 (a) a hard disk drive; and    (b) an interface for optionally operationally connecting, to the computer system, a cache memory for said hard disk drive.    
   
   
       2 . The computer system of  claim 1 , wherein said interface is for reversibly operationally connecting said cache memory to the computer system.  
   
   
       3 . The computer system of  claim 1 , wherein said cache memory is a volatile memory.  
   
   
       4 . The computer system of  claim 1 , wherein said cache memory is a non-volatile memory.  
   
   
       5 . The computer system of  claim 4 , wherein said cache memory is a flash memory.  
   
   
       6 . The computer system of  claim 1 , further comprising: 
 (c) a mechanism, separate from said hard disk drive, for operationally connecting said hard disk drive to said interface.    
   
   
       7 . The computer system of  claim 6 , wherein said mechanism includes a system bus.  
   
   
       8 . The computer system of  claim 6 , further comprising: 
 (d) an operating system for using said cache memory to cache data that are to be written to said hard disk drive.    
   
   
       9 . The computer system of  claim 8 , wherein said operating system uses said cache memory only to cache said data.  
   
   
       10 . The computer system of  claim 1 , wherein said hard disk drive includes a controller, and wherein said interface is directly operationally connected to said controller.  
   
   
       11 . A hard disk drive comprising: 
 (a) a nonvolatile medium for storing data;    (b) a controller for writing said data to said nonvolatile medium and for reading said data from said nonvolatile medium; and    (c) an interface for optionally operationally connecting, to said controller, a cache memory for said nonvolatile medium.    
   
   
       12 . The hard disk drive of  claim 11 , wherein said nonvolatile medium is a magnetic medium.  
   
   
       13 . The hard disk drive of  claim 12 , further comprising: 
 (d) an electromechanical mechanism that is used by said controller for writing said data to said magnetic medium and for reading said data from said magnetic medium.    
   
   
       14 . The hard disk drive of  claim 13 , wherein said electromagnetic mechanism provides said controller random access to said magnetic medium.  
   
   
       15 . The hard disk drive of  claim 11 , wherein said nonvolatile medium is an optical medium.  
   
   
       16 . The hard disk drive of  claim 11 , wherein said interface is for reversibly operationally connecting said cache memory to said controller.  
   
   
       17 . The hard disk drive of  claim 11 , wherein said cache memory is a volatile memory.  
   
   
       18 . The hard disk drive of  claim 11 , wherein said cache memory is a non-volatile memory.  
   
   
       19 . The hard disk drive of  claim 18 , wherein said cache memory is a flash memory.  
   
   
       20 . A method of operating a hard disk drive that includes a nonvolatile data storage medium, comprising the steps of: 
 (a) providing an interface for optionally operationally associating a cache memory with the hard disk drive; and    (b) in exchanging data with the hard disk drive, determining whether said cache memory is operationally associated with the hard disk drive.    
   
   
       21 . The method of  claim 20 , further comprising the step of: 
 (c) in writing said data to the hard disk drive, if said cache memory is operationally associated with the hard disk drive: 
 (i) if said cache memory is full: 
 (A) copying contents of said cache memory to the nonvolatile data storage medium, and  
 (B) writing said data to the nonvolatile data storage medium; and  
 
 (ii) otherwise: writing said data to said cache memory.  
   
   
   
       22 . The method of  claim 20 , further comprising the step of: 
 (c) in reading data from the hard disk drive, if said cache memory is operationally associated with the hard disk drive: 
 (i) determining whether said data reside in said cache memory,  
 (ii) if said data reside in said cache memory: reading said data from said cache memory, and  
 (iii) otherwise: reading said data from the nonvolatile data storage medium.  
   
   
   
       23 . A method of producing computer systems, comprising the steps of: 
 (a) providing each computer system with a respective hard disk drive;    (b) providing each computer system with a respective interface for optionally operationally connecting, to said each computer system, a cache memory for said respective hard disk drive of said each computer system; and    (c) in configuring each computer system for delivery to a respective customer, deciding whether to operationally connect said cache memory to said each computer system at said respective interface of said each computer system.    
   
   
       24 . The method of  claim 23 , further comprising the step of: 
 (d) providing each computer system with a respective mechanism, separate from said respective hard disk drive, for operationally connecting said respective hard disk drive to said respective interface.    
   
   
       25 . The method of  claim 23 , wherein each said hard disk drive includes a controller, and wherein, in each computer system, said respective interface of said each computer system is directly operationally connected to said controller of said respective hard disk drive of said each computer system.  
   
   
       26 . The method of  claim 23 , wherein said cache memories are volatile memories.  
   
   
       27 . The method of  claim 23 , wherein said cache memories are non-volatile memories.  
   
   
       28 . The method of  claim 27 , wherein said cache memories are flash memories.  
   
   
       29 . A computer-readable storage medium having computer-readable code embodied on said computer-readable storage medium, the computer-readable code for exchanging data with a hard disk drive in a computer system that includes an interface for optionally operationally connecting, to the computer system, a cache memory for the hard disk drive, the hard disk drive including a nonvolatile data storage medium, the computer-readable code comprising: 
 (a) program code for determining whether the cache memory is operationally connected to the computer system; and    (b) program code for, if the cache memory is operationally connected to the computer system, then, in writing the data to the hard disk drive: 
 (i) if the cache memory is full: 
 (A) copying contents of the cache memory to the nonvolatile data storage medium, and  
 (B) writing the data to the nonvolatile data storage medium, and  
 
 (ii) otherwise, writing the data to the cache memory.  
   
   
   
       30 . The computer-readable storage medium of  claim 29 , further comprising: 
 (c) program code for, if the cache memory is operationally connected to the computer system, then, in reading the data from the hard disk drive: 
 (i) determining whether the data reside in the cache memory;  
 (ii) if the data reside in the cache memory: reading the data from the cache memory;  
 (iii) otherwise, reading the data from the nonvolatile data storage medium.