Simultaneous activation of virtual devices

• US 8,032,492 B2
• Filed: 11/27/2002
• Issued: 10/04/2011
• Est. Priority Date: 04/10/2002
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Kopylovitz, Haim, Moreshet, Hana, Vishlitzky, Natan
• Primary Examiner(s): TIMBLIN, ROBERT M
• Application Number:
  US10/306,706
• Publication Number:
  US 20030196056A1
• Time in Patent Office: 3,233 Days
• Field of Search: 707/1, 707/204, 707/649, 707/657, 707/660, 711/154, 711/165, 711/4, 711/6, 711202-210, 719/324
• US Class Current: 707/657
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 2003/0697 device management, e.g. handlers, drivers, I/O schedulers
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0614 Improving the reliability of storage systems
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system
• CPC Class Codes: G06F 3/0683 Plurality of storage devices
• CPC Class Codes: Y10S 707/99938 Concurrency, e.g. lock management in shared database
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99954 Version management

Abstract

Establishing a plurality of storage areas includes associating each of a first plurality of storage areas of a first type that contain sections of data with corresponding ones of second plurality of storage areas of a second type having pointers to alternative sections of data storage areas of the first type, where initially none of the second plurality of storage areas is available for accessing data corresponding thereto, and, after associating all of the first and second plurality of storage areas, activating the second plurality of storage areas to make the second plurality of storage areas available for accessing data. Exclusive access may be enabled for all of the first plurality of storage areas prior to activating the second plurality of storage areas or to each storage area one at a time.

Claims

1. A method of establishing a plurality of storage areas, comprising:

associating each of a first plurality of storage areas of a first type that contain sections of data with corresponding ones of a second plurality of storage areas of a second type having pointers to one of;

a section of a corresponding first storage area and a section of a third storage area of the first storage type, the third storage area being separate from the first storage area and the second storage type containing no sections of data, wherein initially none of the second plurality of storage areas is available for accessing data corresponding thereto and wherein all of the storage areas are provided in a single storage device; and

after associating all of the first and second plurality of storage areas, activating the second plurality of storage areas to make the second plurality of storage areas available for accessing data, wherein, in response to an initial write to the first storage area, data is copied from the first storage area to the third storage area prior to the write and a corresponding pointer of the second storage area is made to point to the data at the third storage area.

2. A method, according to claim 1, further comprising:

prior to activating the second plurality of storage areas, setting pointers of the second plurality of storage areas to point to sections of corresponding ones of the first plurality of storage areas.

3. A method, according to claim 1, further comprising:

enabling exclusive access to the first plurality of storage areas prior to activating the second plurality of storage areas; and

disabling exclusive access to the first plurality of storage areas after activating the second plurality of storage areas.

4. A method, according to claim 1, further comprising:

enabling exclusive access to one of the first plurality of storage areas prior to activating a corresponding one of the second plurality of storage areas; and

disabling exclusive access to the one of the first plurality of storage areas after activating the corresponding one of the second plurality of storage areas.

5. A method, according to claim 1, wherein activating the second plurality of storage areas includes providing a value in device headers for each of the second plurality of storage areas.

6. A method, according to claim 1, wherein associating each of the first plurality of storage areas with corresponding ones of the second plurality of storage areas includes making a list of associated storage areas that is used in connection with activating the storage areas.

7. A method, according to claim 1, wherein activating the second plurality of storage areas includes:

setting a particular protection bit for each section of each of the first plurality of storage areas; and

setting a value in each of the headers for each of the first plurality of storage areas, wherein the value indicates that special processing is to be performed in response to a write to a section of the first plurality of storage areas having a protection bit set.

8. A method, according to claim 1, wherein the storage areas are logical devices.

10. A method, according to claim 6, wherein the list is a linked list.

9. A method of establishing a plurality of storage areas, comprising:

associating each of a first plurality of storage areas of a first type that contain sections of data with corresponding ones of a second plurality of storage areas of a second type having pointers to one of;

a section of a corresponding first storage area and a section of a third storage area of the first storage type, the third storage area being separate from the first storage area and the second storage type containing no sections of data, wherein initially none of the second plurality of storage areas is available for accessing data corresponding thereto;

after associating all of the first and second plurality of storage areas, activating the second plurality of storage areas to make the second plurality of storage areas available for accessing data, wherein, in response to an initial write to the first storage area, data is copied from the first storage area to the third storage area prior to the write and a corresponding pointer of the second storage area is made to point to the data at the third storage area; and

establishing a consistency group for the first storage areas and the second storage areas.

11. Computer software, provided in a non-transitory computer-readable storage medium, that establishes a plurality of storage areas, comprising:

executable code that associates each of a first plurality of storage areas of a first type that contain sections of data with corresponding ones of a second plurality of storage areas of a second type having pointers to one of;

a section of a corresponding first storage area and a section of a third storage area of the first storage type, the third storage area being separate from the first storage area and the second storage type containing no sections of data, wherein initially none of the second plurality of storage areas is available for accessing data corresponding thereto and wherein all of the storage areas are provided in a single storage device; and

executable code that, after associating all of the first and second plurality of storage areas, activates the second plurality of storage areas to make the second plurality of storage areas available for accessing data, wherein, in response to an initial write to the first storage area, data is copied from the first storage area to the third storage area prior to the write and a corresponding pointer of the second storage area is made to point to the data at the third storage area.

12. Computer software, according to claim 11, further comprising:

executable code that, prior to activating the second plurality of storage areas, sets pointers of the second plurality of storage areas to point to sections of corresponding ones of the first plurality of storage areas.

13. Computer software, according to claim 11, further comprising:

executable code that enables exclusive access to the first plurality of storage areas prior to activating the second plurality of storage areas; and

executable code that disables exclusive access to the first plurality of storage areas after activating the second plurality of storage areas.

14. Computer software, according to claim 11, further comprising:

executable code that enables exclusive access to one of the first plurality of storage areas prior to activating a corresponding one of the second plurality of storage areas; and

executable code that disables exclusive access to the one of the first plurality of storage areas after activating the corresponding one of the second plurality of storage areas.

15. Computer software, according to claim 11, wherein executable code that activates the second plurality of storage areas includes executable code that provides a value in device headers for each of the second plurality of storage areas.

16. Computer software, according to claim 11, further comprising:

executable code that establishes a consistency group for the first storage areas and the second storage areas.

17. Computer software, according to claim 11, wherein executable code that associates each of the first plurality of storage areas with corresponding ones of the second plurality of storage areas also makes a list of associated storage areas that is used in connection with activating the storage areas.

18. Computer software, according to claim 17, wherein the list is a linked list.

19. Computer software, according to claim 11, wherein executable code that activates the second plurality of storage areas also sets a particular protection bit for each section of each of the first plurality of storage areas and also sets a value in each of the headers for each of the first plurality of storage areas, wherein the value indicates that special processing is to be performed in response to a write to a section of the first plurality of storage areas having a protection bit set.