Data processing system and method

• US 7,937,404 B2
• Filed: 02/04/2005
• Issued: 05/03/2011
• Est. Priority Date: 02/04/2005
• Status: Active Grant

• Current Assignee: Valtrus Innovations Limited (f/k/a Dolya Holdco 9 Limited) (Key Patent Innovations Limited)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Tripathi, Shailendra
• Primary Examiner(s): Fleurantin; Jean B
• Application Number:
  US11/883,231
• Publication Number:
  US 20080140997A1
• Time in Patent Office: 2,279 Days
• Field of Search: 707 1- 10, 707100-1041, 707200-206, 707600-831, 711100-103, 711/111, 711/151, 711/163
• US Class Current: 707/770
• 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 2212/6026 Prefetching based on access pattern detection, e.g. stride based prefetch
• CPC Class Codes: G06F 2212/6028 Prefetching based on hints or prefetch instructions

Abstract

A data processing system and method uses metadata associated with data to be retrieved from storage to identify further data to be retrieve at least a portion of that further data from the storage in accordance with a prefetch policy. A first interface receives a data access request from an application, and a prefetcher reads metadata associated with a file and uses the metadata to identify further data to be prefetched and placed in storage or memory having a performance greater than the performance of persistent storage.

Claims

1. A data processing system comprising:

a first interface to receive a data access request from an application and a second interface for performing an operation in relation to a data stored using persistent storage, and

a prefetcher to read metadata associated with a file containing data to be retrieved based on the data access request;

to select at least one access pattern associated with a request for data from the storage; and

to use the metadata in identifying further data to be prefetched and placed in storage or memory having a performance that is greater than the performance of the persistent storage.

2. A data processing system as claimed in claim 1 in which the metadata comprises data to identify, or associated with, at least one access pattern for the data.

3. A data processing system as claimed in claim 2 in which the metadata comprises data to identify, or associated with, a plurality of access patterns.

4. A data processing system as claimed in claim 1 further comprising a correlator to determine a least one degree of similarity between the metadata and historical data access.

5. A data processing system as claimed in claim 4 comprising a selector to select at least one or some of the metadata for use in prefetching the further data according to the at least one determined degree of similarity.

6. A data processing system as claimed in claim 1 in which the metadata comprises data identifying, or associated with, at least one of a sequential, a looping, a temporally-clustered or a probabilistic access pattern.

7. A data processing system as claimed in claim 1 in which the metadata is stored within a predetermined data structure.

8. A data processing system as claimed in claim 7 in which the predetermined data structure is a unique identifier data structure.

9. A data processing system as claimed in claim 7 in which the data structure is an inode.

14. A program comprising code to implement a system or method as claimed in claim 1.

16. A data processing system as claimed in claim 1, further comprising:

an inode table that stores the metadata associated with the file and with other files.

17. A data processing system as claimed in claim 16, wherein the metadata stored in the inode table comprises:

Unix file system context information;

device identifier information for identifying a device holding the file;

an inode number;

a mode indication indicating what the inode represents as well as associated access rights; and

use identifiers.

18. A data processing system as claimed in claim 17, wherein the metadata stored in the inode table further comprises:

a times field identifying creation, modification and write times associated with the file;

an inode operations field containing a pointer to a block of routine addresses that are specific to an underlying file system and which perform operations in relation to the inode;

a count field providing an indication of a number of system components currently using the inode;

a lock field that is used to lock the inode when the inode is being read by the underlying file system; and

a dirty field that provides an indication that the inode has been written to and that the underlying file system needs to modify.

19. A data processing system as claimed in claim 1, wherein the prefetcher also receives information regarding an amount of free memory within a cache memory in determining what if any data placed to place in the storage or the memory having the performance that is greater than the performance of the persistent storage.

10. A data processing system to prefetch data from storage in advance of an executable entity requesting the data, the system comprising:

means to select at least one access pattern associated with a request for data from the storage, based on metadata stored in a table,

means to prefetch further data from the storage according to a selected access pattern, and

means to store the further data in the storage and having a performance that is greater than the performance of the persistent storage.

11. A data processing method to retrieve data from storage in response to a program requesting first data;

the method comprising the steps of;

processing, by a computer, metadata associated with the first data to identify data to be retrieved from the storage;

retrieving, by the computer, the identified data from the storage; and

using, by the computer, the metadata in identifying further data to be prefetched and placed in another storage or memory having a performance that is greater than the performance of the storage.

12. A method to prefetch data from storage, the method being performed by a computer and comprising the steps of:

receiving a request to access a file from an application;

processing the request to identify a unit of data associated with the request;

processing metadata associated with the request to access the file to identify at least one further unit of data;

retrieving at least one of the unit of data associated with the request and the at least one further unit of data from the storage;

servicing the request to access the file by forwarding at least a portion of the unit of data associated with the request to the application; and

storing at least a portion of the at least one further unit of data in a memory.

13. A computer readable storage medium storing a program comprising computer executable code to process a data access request from an executable entity to select at least one access pattern associated with a request for data from the storage and to perform an operation in relation to data stored using a storage medium, and computer executable code to read metadata associated with the stored data and to use the metadata to identify further data to be prefetched and stored using further storage having a performance that is better than the performance of the storage medium.

15. Computer readable storage storing a computer program as claimed in claim 13.