Remote data mirroring

• US 7,055,059 B2
• Filed: 12/27/2002
• Issued: 05/30/2006
• Est. Priority Date: 04/23/1993
• Status: Expired due to Term

• Current Assignee: EMC Corporation (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Vishlitzky, Natan, Ofek, Yuval, Alterescu, Bruno, Yanai, Moshe, Castel, Daniel, Shklarsky, Gadi
• Primary Examiner(s): LE, DIEU MINH T
• Application Number:
  US10/330,715
• Publication Number:
  US 20040073831A1
• Time in Patent Office: 1,250 Days
• Field of Search: 714/7, 714/6, 714 11- 13, 714/707, 714/718, 714/798, 710/61, 711/100, 711150-151, 711162-163, 709/217, 709/219, 709/248
• US Class Current: 714/6.32
• CPC Class Codes: G06F 11/2066 Optimisation of the communication load
• CPC Class Codes: G06F 11/2071 using a plurality of controllers
• CPC Class Codes: G06F 11/2074 Asynchronous techniques
• CPC Class Codes: G06F 11/2079 Bidirectional techniques
• CPC Class Codes: G06F 11/2082 Data synchronisation
• 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 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0661 Format or protocol conversion arrangements
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: G11B 20/1217 on discs
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• CPC Class Codes: H04L 69/26 Special purpose or proprietary protocols or architectures network applications for proprietary or special purpose networking environments H04L67/12
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation

Abstract

Two data storage systems are interconnected by a data link for remote mirroring of data. Each volume of data is configured as local, primary in a remotely mirrored volume pair, or secondary in a remotely mirrored volume pair. Normally, a host computer directly accesses either a local or a primary volume, and data written to a primary volume is automatically sent over the link to a corresponding secondary volume. Each remotely mirrored volume pair can operate in a selected synchronization mode including synchronous, semi-synchronous, adaptive copy—remote write pending, and adaptive copy—disk. Direct write access to a secondary volume is denied if a “sync required” attribute is set for the volume and the volume is not synchronized.

Claims

1. A system for remote mirroring of data, said system comprising:

a first data storage system, and

a second data storage system remote from the first data storage system and linked to the first data storage system for transfer of data between the first data storage system and the second data storage system;

wherein the system for remote mirroring of data is programmed to configure logical units of storage in selected mirroring configuration states such that each logical unit of storage is either local to either the first or second data storage system, or is a member of a remotely mirrored pair including a primary logical unit of storage in one of the first or second data storage systems and a secondary logical unit of storage in the other of the first or second data storage systems; and

wherein the system for remote mirroring of data is programmed to maintain each remotely minored pair in a selected synchronization mode including a synchronous mode and at least one asynchronous mode, and for said at least one asynchronous mode, the data storage system containing the primary logical unit of storage of said each remotely mirrored pair is programmed to maintain a record of changes pending to the secondary logical unit of storage of the remotely mirrored pair in order to facilitate synchronization of the secondary logical unit of storage of said each remotely mirrored pair with the primary logical unit of storage of said each remotely minored pair.

2. The system for remote mirroring of data as claimed in claim 1, wherein the logical units of storage are logical volumes of storage.

3. The system mirroring of data as claimed in claim 1, wherein the record of changes pending to the secondary logical unit of storage of the remotely mirrored pair includes a list of pending tracks of write data transmitted over a data link between the first and second data storage systems.

4. The system for remote mirroring of data as claimed in claim 1, wherein said at least one asynchronous mode includes a semi-synchronous mode in which the primary and secondary logical units of storage of said each remotely minored pair are synchronized prior to initiating a next write operation to said each remotely mirrored pair.

5. The system for remote mirroring data as claimed in claim 1, wherein said at least one asynchronous mode includes an adaptive copy mode in which further write access to said each remotely mirrored pair is suspended when there is at least a specified number of changes pending to the secondary logical unit of storage of said each remotely mirrored pair.

6. The system for remote mirroring of as claimed in claim 5, wherein the specified number of changes pending to the secondary logical unit of storage of said each remotely mirrored pair is a specified number of pending tracks of data to be written to the secondary logical unit of storage of said each remotely mirrored pair.

7. The system for remote mirroring of data as claimed in claim 6, wherein the specified number of pending tracks of data are pending tracks of data not yet written to cache memory of the data storage system containing the secondary logical unit of storage of said each remotely mirrored pair.

8. The system for remote mirroring of data as claimed in claim 6, wherein the specified number of pending tracks of data are pending tracks of data not yet written to disk memory of the data storage system containing the secondary logical unit of storage of said each remotely mirrored pair.

9. The system for remote mirroring of data as claimed in claim 1, wherein the first data storage system is programmed to maintain a table of validity of data of secondary logical units of storage in the second data storage system.

10. The system for remote mirroring of data as claimed in claim 1 wherein the second data storage system is programmed to maintain a table of validity of data of primary logical units of storage in the first data storage system.

11. The system for remote mirroring of data as claimed in claim 1, which is programmed to respond to a request to synchronize a specified remote mirrored pair by synchronizing the specified remote mirrored pair.

12. The system for remote mirroring of data as claimed in claim 1, wherein each secondary logical unit of storage has a “

sync required”

attribute for selectively preventing said each secondary logical unit of storage from being accessed by the data storage system containing the secondary logical unit of storage when a state change of the secondary logical unit of storage is attempted while the secondary logical unit of storage is not synchronized.

13. The system for remote mirroring of data as claimed in claim 12, wherein the attempted state change attempts to change the secondary logical unit of storage to a read-only state.

14. The system for remote mirroring of data as claimed in claim 12, wherein the attempted state change attempts to change the secondary logical unit of storage to a read-write state.

15. The system for remote mirroring of data as claimed in claim 1, which is programmed to respond to a request to change a direction of mirroring of a specified remote mirrored pair by changing the direction of mirroring of the specified remote mirrored pair.

16. A system for remote mirroring of data, said system comprising:

a first data storage system, and

a second data storage system remote from the first data storage system and linked to the first data storage system for transfer of data between the first data storage system and the second data storage system;

wherein the system for remote mirroring of data is programmed to configure logical units of storage in selected mirroring configuration states such that each logical unit of storage is either local to either the first or second data storage system, or is a member of a remotely mirrored pair including a primary logical unit of storage in one of the first or second data storage systems and a secondary logical unit of storage in the other of the first or second data storage systems; and

wherein the system for remote mirroring of data is programmed to maintain each remotely mirrored pair in a selected synchronization mode including a synchronous mode and a semi-synchronous mode in which the primary and secondary logical units of storage of said each remotely mirrored pair are synchronized prior to initiating a next write operation to said each remotely mirrored pair.

17. A system for remote mirroring of data, said system comprising:

a first data storage system, and

a second data storage system remote from the first data storage system and linked to the first data storage system for transfer of data between the first data storage system and the second data storage system;

wherein the system for remote mirroring of data is programmed to configure logical units of storage in selected minoring configuration states such that each logical unit of storage is either local to either the first or second data storage system, or is a member of a remotely mirrored pair including a primary logical unit of storage in one of the first or second data storage systems and a secondary logical unit of storage in the other of the first or second data storage systems; and

wherein the system for remote minoring of data is programmed to maintain each remotely minored pair in a selected synchronization mode including a synchronous mode and at least one asynchronous mode, wherein said at least one asynchronous mode includes an adaptive copy mode in which further write access to said each remotely mirrored pair is suspended when there is at least a specified number of changes pending to the secondary logical unit of storage of said each remotely mirrored pair.

18. The system for remote mirroring data as claimed in claim 17, wherein the specified number of changes pending to the secondary logical unit of storage of said each remotely mirrored pair is a specified number of pending tracks of data to be written to the secondary logical unit of storage of said each remotely mirrored pair.

19. The system for remote mirroring of data as claimed in claim 17, wherein the specified number of changes are changes not yet written to cache memory of the data storage system containing the secondary logical unit of storage of said each remotely mirrored pair.

20. The system for remote mirroring of data as claimed in claim 17, wherein the specified number of changes are changes not yet written to disk memory of the data storage system containing the secondary logical unit of storage of said each remotely mirrored pair.

21. A system for remote mirroring of data, said system comprising:

a first data storage system, and

a second data storage system remote from the first data storage system and linked to the first data storage system for transfer of data between the first data storage system and the second data storage system;

wherein the system for remote mirroring of data is programmed to configure logical units of storage in selected mirroring configuration states such that each logical unit of storage is either local to either the first or second data storage system, or is a member of a remotely mirrored pair including a primary logical unit of storage in one of the first or second data storage systems and a secondary logical unit of storage in the other of the first or second data storage systems; and

wherein the system for remote mirroring of data is programmed to maintain each remotely mirrored pair in a selected synchronization mode including a synchronous mode and at least one asynchronous mode, and each secondary logical unit of storage has a “

sync required”

attribute for selectively preventing said each secondary logical unit of storage from being accessed by the data storage system containing the secondary logical unit of storage when a state change of the secondary logical unit of storage is attempted while the secondary logical unit of storage is not synchronized.

22. The system for remote mirroring of data as claimed in claim 21, wherein the attempted state change attempts to change the secondary logical unit of storage to a read-only state.

23. The system for remote mirroring of as claimed in claim 21, wherein the attempted state change attempts to change the secondary logical unit of storage to a read-write state.

24. The system for remote mirroring of data as claimed in claim 21, which is programmed to respond to a request to change a direction of mirroring of a specified remote mirrored pair by changing the direction of mirroring of the specified remote mirrored pair.