Magnetic disk unit, file management system, and file management method

Abstract

A file management system including a hard disk unit and a file management unit. The file management unit manages data to be read and written from and into the hard disk unit such that data in a file is continuous in a predetermined logical address space and specifies a target data requested to be read and written from and into the hard disk unit by a predetermined logical address within the logical address space. The hard disk unit performs processing of reading and writing data after translating the predetermined logical addresses specifying the data requested to be read and written into LBAs. Then the hard disk unit performs defragmentation of data recorded on a magnetic disk based on the predetermined logical addresses.

1 . A method of managing files in an external storage device of a computer, comprising the steps of:
 performing deletion of data on a recording medium based on a remove request received from the computer;   classifying the data based on whether or not the data is stored in the recording medium and assignment of a predetermined second logical address in the recording medium to the data,
 holding in a cache memory target data of a read/write process between the external storage device and the computer, 
 classifying and managing data held in the cache memory as one of clean/full, clean/fragmented, dirty/full, and dirty/fragmented based on whether or not the data is saved in the recording medium, wherein clean indicates that data has been saved, dirty indicates that data has not been saved, full indicates that all of the contents within a stride is composed of blocks of consecutive frame addresses, and fragmented indicates that the contents of a stride is composed of blocks of nonconsecutive frame addresses; 
   optimizing a layout of the data stored in the recording medium by storing data held in the cache memory into the recording medium in accordance with the classification, based on the second logical address, at a predetermined time to eliminate fragmentation; and
 defragmenting data recorded on the recording medium in accordance with the classification of the data responsive to whether or not the data is stored in the recording medium and whether or not the data has a second logical address. 
   
   
   
       2 . The method described in  claim 1 , further comprising the steps of
 registering data held in the cache memory in a layout correspondence table; and   updating the layout correspondence table responsive to the deletion of data.   
   
   
       3 . A method of performing defragmentation of data written on a recording medium from a computer comprising the steps of:
 performing a read/write process from and into the recording medium based on a read/write request on the data received from the computer;   holding in a cache memory target data of the read/write process; said cache memory holding data to be written to the recording medium or data read from the recording medium;   classifying and managing data held in the cache memory as one of clean/full, clean/fragmented type, dirty/full type, and dirty/fragmented type based on whether or not the data is saved in the recording medium, wherein clean indicates that data has been saved, dirty indicates that data has not been saved, full indicates that all of the contents within a stride is composed of blocks of consecutive frame addresses, and fragmented indicates that the contents of a stride is composed of blocks of nonconsecutive frame addresses;   registering data held in the cache memory in a layout correspondence table;   examining a file with a range of the frame addresses; the file having not less than a single stride size and being discontinuously arranged on the magnetic disk;   selecting at least one stride of a frame address by examining whether data of the dirty/fragment type includes data which can constitute a full stride and comparing with data registered in the layout correspondence table;   recompiling data in the cache memory into stride units to produce recompiled data and holding the recompiled data as clean/full type;   writing data held in the dirty/full cache area into a continuous area on the recording medium; and   updating the layout correspondence table responsive to the read/write process.   
   
   
       4 . A method of reusing cache memory in an external storage device of a computer comprising the steps of:
 performing a read/write process from and into a recording medium based on a read/write request on data received from the computer;   holding in the cache memory target data of the read/write process; said cache memory holding data to be written to the recording medium or data read from the recording medium;   classifying and managing data held in the cache memory as one of clean/full, clean/fragmented type, dirty/full type, and dirty/fragmented type based on whether or not the data is saved in the recording medium, wherein clean indicates that data has been saved, dirty indicates that data has not been saved, full indicates that all of the contents within a stride is composed of blocks of consecutive frame addresses, and fragmented indicates that the contents of a stride is composed of blocks of nonconsecutive frame addresses;   removing data from clean/full and the clean/fragmented cache areas; and   if additional cache space is needed, removing of data from the dirty/fragmented cache area.   
   
   
       5 . The method in  claim 4  further comprising the steps of
 registering data held in the cache memory in a layout correspondence table; and   updating the layout correspondence table in response to writing data in the cache memory to the recording medium.