Storage volume handling system which utilizes disk images

• US 5,991,542 A
• Filed: 09/13/1996
• Issued: 11/23/1999
• Est. Priority Date: 09/13/1996
• Status: Expired

• Current Assignee: Apple Inc.
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Kateley, James F., Murphy, Colm, Han, Byron B., Fitzgerald-Smith, Kenneth
• Primary Examiner(s): Levy, Stuart S.
• Assistant Examiner(s): FIELDS, KENNETH WAYNE
• Application Number:
  US08/713,500
• Time in Patent Office: 1,166 Days
• Field of Search: 395/200.42, 395/200.45, 395/200.47, 395/200.49, 395/200.33, 395/712, 395/200.77
• US Class Current: 717/167
• CPC Class Codes: G06F 3/0626 Reducing size or complexity of storage systems
• CPC Class Codes: G06F 3/0667 at data level, e.g. file, record or object virtualisation
• CPC Class Codes: G06F 3/0676 Magnetic disk device
• CPC Class Codes: G06F 8/63 Image based installation; Cloning; Build to order

Abstract

Disk images, and the like, are used to emulate storage volumes for the distribution of computer software. An image of a data storage volume, such as a hard disk drive, is stored in a file having a format that enables it to exhibit a behavior which is the same as the storage volume itself. The image files are accessed by means of an associated driver which can support a variety of different file system protocols, thereby permitting the files themselves to be independent of the format requirements of particular file systems. The data in the image file can be compressed in a manner such that a storage volume being emulated appears to be of a specified size, while actually requiring less space to store its contents. With these properties, the image files can be mounted in the manner of a hardware storage device, and large files can be readily transmitted and downloaded in an electronic format. Since the files are preserved in their original form, end-to-end verification remains possible, to ensure the integrity of the downloaded files. Multiple images can be combined into a single tome, for installation at a remote site using a one-button approach.

Claims

1. A system for accessing computer-readable files stored on a source device, by a plurality of target computers comprising:

means for creating a disk image of the source device, wherein said source device is a physical storage volume on which said computer-readable files to be accessed by said plurality of target computers are located, and for storing said disk image on a storage device that is accessible to said plurality of target computers, wherein said disk image is a virtual representation of said physical storage volume such that it includes volume format information that reflects the format of said physical storage volume, and which enables said disk image to be mounted at each of said plurality of target computers; and

a disk image driver at each of said plurality of target computers having access to file format information which enables said target computers to read files, which exhibit different file formats, contained on said disk image.

2. The system of claim 1 wherein said disk image driver includes an index which identifies correspondence between address location in said storage volume and address locations in said disk image.

3. The system of claim 2 wherein said disk image contains a compressed version of data in said files, and wherein said index further includes information pertaining to the manner in which the data was compressed.

4. The system of claim 3 wherein the data in said disk image is divided into individual chunks which are separately compressed and said index contains, for each chunk, the address of the chunk of data in the file, the address for the corresponding compressed data in the disk image, and an identification of a compression algorithm via which the data of that chunk was compressed.

5. The system of claim 4 wherein different chunks of data are compressed via different respective algorithms.

6. The system of claim 4 wherein different chunks of data have different respective sizes.

7. The system of claim 1 wherein said disk image driver includes data pertaining to different types of file systems, to thereby enable said disk image driver to access disk images stored in different disk image file formats respectively related to said different types of file systems.

8. The system of claim 1, wherein said disk image is stored on the storage device in a compressed read/only format comprising a file which contains compressed versions of chunks of data stored in said physical storage volume, and an index which provides a mapping between logical address blocks in said physical storage volume and addresses of corresponding compressed data in said file.

9. The system of claim 8, wherein said index contains information pertaining to the manner in which the chunks of data were compressed.

10. The system of claim 9, wherein the data in said volume is divided into individual chunks which are separately compressed and said index contains, for each chunk, the address of the chunk of data in said physical storage volume, the address for the corresponding compressed data in said disk image, and an identification of a compression algorithm via which the data of that chunk was compressed.

11. The system of claim 10, wherein different chunks of data are compressed via different respective algorithms.

12. The system of claim 10, wherein different chunks of data have different respective sizes.

13. The system of claim 10, wherein said uncompressed read/only format also has an associated index which provides a mapping between logical address blocks in said physical storage volume and addresses of corresponding data in the file.

14. The system of claim 1, wherein said disk image is stored on the storage device in a read/write format comprising a file which contains a copy of every logical address block in said physical storage volume, regardless of whether the blocks contain data.

15. The system of claim 1, wherein said disk image is stored on the storage device in an uncompressed read/only format comprising a file which contains volume information and a copy of only those logical address blocks of the physical storage volume which contain data.

16. A method for providing a remote computer access to files stored on a source device, comprising the steps of:

creating a disk image of said source device, wherein said source device is a physical storage volume which contains said files to be accessed by said remote computer, and wherein said disk image is a virtual representation of said physical storage volume in that said disk image includes volume format information that reflects the format of said physical storage volume;

generating a script file which includes an identification of said disk image;

launching said script file at said remote computer; and

mounting, at said remote computer, the disk image identified in said script file using a disk image driver that has access to volume format information which is needed to mount files, exhibiting different file formats, on the disk image.

17. The method of claim 16 wherein said script file also includes an identification of an executable program, and further including the step of running said program at the remote computer after mounting said disk image.

18. The method of claim 17 wherein said program is an installer program which installs files from the mounted disk image onto the remote computer.

19. The method of claim 16 wherein a plurality of disk images are created and identified in said script file, and wherein all of the disk images identified in said script file are mounted at said remote computer.

20. The method of claim 16 further comprising the step of:

selectively storing said disk image in a storage medium device in any one of the following disk image file formats;

a read/write format comprising a file which contains a copy of every logical address block in said physic al storage volume, regardless of whether the blocks contain data;

an uncompressed read/only format comprising a file which contains volume information and a copy of only those logical address blocks of said physical storage volume which contain data; and

a compressed read/only format comprising a file which contains compressed versions of chunks of data stored in said physical storage volume, and an index which provides a mapping between logical address blocks in said physical storage volume and addresses of corresponding compressed data in said file.