System for dynamically controlling cache manager maintaining cache index and controlling sequential data access

• US 5,537,568 A
• Filed: 12/12/1994
• Issued: 07/16/1996
• Est. Priority Date: 06/04/1992
• Status: Expired due to Term

• Current Assignee: EMC Corporation (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Vishlitzky, Natan, Alterescu, Bruno, Yanai, Moshe, Castel, Daniel
• Primary Examiner(s): Kim, Matthew M.
• Application Number:
  US08/354,489
• Time in Patent Office: 582 Days
• Field of Search: 364/200 MS File, 364/900 MS File, 395/425, 395/403, 395/445, 395/497.01, 395/463, 395/457
• US Class Current: 711/118
• CPC Class Codes: G06F 12/0862 with prefetch
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 12/121 using replacement algorithms
• CPC Class Codes: G06F 12/123 with age lists, e.g. queue, most recently used [MRU] list or least recently used [LRU] list
• CPC Class Codes: G06F 2212/502 using adaptive policy
• CPC Class Codes: G06F 2212/6026 Prefetching based on access pattern detection, e.g. stride based prefetch
• CPC Class Codes: Y10S 427/104 Utilizing low energy electromagnetic radiation, e.g. microwave, radio wave, IR, UV, visible, actinic laser

Abstract

A cache management system and method monitors and controls the contents of cache memory coupled to at least one host and at least one data storage device. A cache indexer maintains a current index of data elements which are stored in cache memory. A sequential data access indicator, responsive to the cache index and to a user selectable sequential data access threshold, determines that a sequential data access is in progress for a given process and provides an indication of the same. The system and method allocate a micro-cache memory to any process performing a sequential data access. In response to the indication of a sequential data access in progress and to a user selectable maximum number of data elements to be prefetched, a data retrieval requestor requests retrieval of up to the selected maximum number of data elements from a data storage device. A user selectable number of sequential data elements determines when previously used micro-cache memory locations will be overwritten. A method of dynamically monitoring and adjusting cache management parameters is also presented.

Claims

1. A cache management system including a cache manager, for monitoring and controlling contents of cache memory, said cache management system comprising:

a cache indexer for maintaining a cache index of data elements stored in at least cache memory;

a sequential data access indicator, responsive to said cache index, for detecting a plurality of sequential data elements stored in said cache memory, and for providing an indication of said plurality of sequential data elements when said plurality of sequential data elements reaches a sequential data access indicator threshold; and

a dynamic cache management system adjuster, responsive to said indication of said plurality of sequential data elements, for dynamically adjusting said sequential data access indicator threshold.

2. A cache management system including a cache manager, for monitoring and controlling contents of cache memory, said cache management system comprising:

a cache indexer for maintaining a cache index of data elements stored in at least cache memory;

a sequential data access indicator, responsive to said cache index, for detecting a plurality of sequential data elements stored in said cache memory, and for providing an indication of said plurality of sequential data elements when said plurality of sequential data elements reaches a sequential data access indicator threshold;

a data retrieval requester, responsive to said detection of said plurality of sequential data elements for requesting retrieval form at least one data storage device of at least one data element, said at least one data storage device having longer term storage than said cache memory; and

a dynamic cache management system adjuster, responsive to said indication of said plurality of sequential data elements, for dynamically adjusting said sequential data access indicator threshold.