System and method for dynamically resynchronizing backup data

• US 6,260,124 B1
• Filed: 08/13/1998
• Issued: 07/10/2001
• Est. Priority Date: 08/13/1998
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: McBride, Gregory Edward, Crockett, Robert Nelson, Kern, Ronald Maynard
• Primary Examiner(s): Kim, Matthew
• Assistant Examiner(s): BATAILLE, PIERRE MICHE
• Application Number:
  US09/134,543
• Time in Patent Office: 1,062 Days
• Field of Search: 711/161, 711/162, 711/165, 711/112, 711/111, 711/114, 711/154, 714/5, 714/6, 714/12, 714/7, 714/20
• US Class Current: 711/162
• CPC Class Codes: G06F 11/2064 while ensuring consistency
• CPC Class Codes: G06F 11/2082 Data synchronisation

Abstract

Backup storage is resynchronized to primary storage, ensuring that any new updates received during resynchronization are applied in the proper order relative to resynchronization data. Under normal operations, a data mover mirrors data stored in primary storage to backup storage. If an error condition arises, preventing mirroring, the data mover stores newly received data in primary storage without mirroring the data to backup storage. The data mover also identifies this data in an update map. When the error condition ends, the data mover performs a static resynchronization process, serving to update the backup storage with the un-mirrored data, identified in the update map. When new data is received during static resynchronization, a dynamic resynchronization process is invoked to accurately process the updates. Dynamic resynchronization ensures that newly received data records are copied to backup storage in the proper order (if at all) with respect to versions of the same data being processed by static resynchronization.

Claims

1. A method of resynchronizing data contained in a data storage system having primary and backup storage sites both coupled to a data mover, the primary storage site coupled to a host that provides write data to the primary storage site, the data mover serving to mirror data stored at the primary storage site upon the backup storage site, where during predetermined error conditions the data mover stores data received by the storage system in the primary storage site without mirroring the data to the backup storage site, the method comprising:

after termination of an error condition, the data mover performing a static resynchronization process comprising;

identifying data received during the error condition at the primary storage site without mirroring to the backup storage site;

reading the identified data from the primary storage site at one or more read times comprising;

repeatedly reading groups of the identified data until all identified data has been read; and

for each group of read data, storing indicia representing the read data in a progress queue along with a time of the reading;

writing the read data to the backup storage site; and

the primary storage site receiving update data from the host for storage while no error condition is occurring, the update data representing changes to data already existing on the primary storage site, and in response;

the data mover determining whether the static resynchronization process is in progress, and if not, copying the update data to the backup storage site;

if the static resynchronization process is in progress, the data mover determining whether the static resynchronization process is already processing data corresponding to the existing data, and if not, copying the update data to the backup storage site;

if the static resynchronization process is already processing data corresponding to the existing data, the data mover copying the update data to the backup storage site only if the host provided the update data to the primary storage site after the static resynchronization read time for the data already being processed comprising;

the data mover referencing the progress queue to determine the time of reading of the updated data;

the data mover copying the data to the backup storage site only if the host provided the updated data to the primary storage site after the time of reading of the updated data, otherwise discarding the updated data.

2. A method of resynchronizing data contained in a data storage system having primary and backup storage sites both coupled to a data mover, the primary storage site coupled to a host that provides write data to the primary storage site, the data mover serving to mirror data stored at the primary storage site upon the backup storage site, where during predetermined error conditions the data mover stores data received by the storage system in the primary storage site without mirroring the data to the backup storage site, the method comprising:

after termination of an error condition, the data mover performing a static resynchronization process comprising;

identifying data received during the error condition at the primary storage site with out mirroring to the backup storage site;

reading the identified data from the primary storage site at one or more read times comprising;

repeatedly reading groups of the identified data until all identified data has been read; and

for each group of read data, storing indicia representing the read data in a progress queue along with a time of the reading;

writing the read data to the backup storage site; and

the primary storage site receiving update data from the host for storage while no error condition is occurring, the update data representing changes to data already existing on the primary storage site, and in response;

the data mover determining whether the static resynchronization process is in progress, and if not, copying the update data to the backup storage site;

if the static resynchronization process is in progress, the data mover determining whether the static resynchronization process is already processing data corresponding to the existing data, and if not, copying the update data to the backup storage site;

if the static resynchronization process is already processing data corresponding to the existing data, the data mover copying the update data to the backup storage site only if the host provided the update data to the primary storage site after the static resynchronization read time for the data already being processed;

determining whether static resynchronization has finished and the received update data was provided by the host to the primary storage after the read time of static resynchronization, and only then clearing the progress queue and the update map.

3. A signal-bearing medium tangibly embodying a program of machine-readable instructions executable by a digital processing machine to perform a method of resynchronizing data contained in a data storage system having primary and backup storage sites both coupled to a data mover, the primary storage site coupled to a host that provides write data to the primary storage site, the data mover serving to mirror data stored at the primary storage site upon the backup storage site, where during predetermined error conditions the data mover stores data received by the storage system in the primary storage site without mirroring the data to the backup storage site, the method comprising:

after termination of an error condition, the data mover performing a static resynchronization process comprising;

identifying data received during the error condition at the primary storage site without mirroring to the backup storage site;

reading the identified data from the primary storage site at one or more read times comprises;

repeatedly reading groups of the identified data until all identified data has been read; and

for each group of read data, storing indicia representing the read data in a progress queue along with a time of the reading;

writing the read data to the backup storage site; and

the primary storage site receiving update data from the host for storage while no error condition is occurring, the update data representing changes to data already existing on the primary storage site, and in response;

the data mover determining whether the static resynchronization process is in progress, and if not, copying the update data to the backup storage site;

if the static resynchronization process is in progress, the data mover determining whether the static resynchronization process is already processing data corresponding to the existing data, and if not, copying the update data to the backup storage site;

if the static resynchronization process is already processing data corresponding to the existing data, the data mover copying the update data to the backup storage site only if the host provided the update data to the primary storage site after the static resynchronization read time for the data already being processed comprising;

the data mover referencing the progress queue to determine the time of reading of the updated data;

the data mover copying the data to the backup storage site only if the host provided the updated data to the primary storage site after the time of reading of the updated data, otherwise discarding the updated data.

4. A signal-bearing medium tangibly embodying a program of machine-readable instructions executable by a digital processing machine to perform a method of resynchronizing data contained in a data storage system having primary and backup storage sites both coupled to a data mover, the primary storage site coupled to a host that provides write data to the primary storage site, the data mover serving to mirror data stored at the primary storage site upon the backup storage site, where during predetermined error conditions the data mover stores data received by the storage system in the primary storage site without mirroring the data to the backup storage site, the method comprising:

after termination of an error condition, the data mover performing a static resynchronization process comprising;

identifying data received during the error condition at the primary storage site without mirroring to the backup storage site;

reading the identified data from the primary storage site at one or more read times comprising;

repeatedly reading groups of the identified data until all identified data has been read; and

for each group of read data, storing indicia representing the read data in a progress queue along with a time of the reading;

writing the read data to the backup storage site; and

the primary storage site receiving update data from the host for storage while no error condition is occurring, the update data representing changes to data already existing on the primary storage site, and in response;

the data mover determining whether the static resynchronization process is in progress, and if not, copying the update data to the backup storage site;

if the static resynchronization process is in progress, the data mover determining whether the static resynchronization process is already processing data corresponding to the existing data, and if not, copying the update data to the backup storage site;

if the static resynchronization process is already processing data corresponding to the existing data, the data mover copying the update data to the backup storage site only if the host provided the update data to the primary storage site after the static resynchronization read time for the data already being processed;

determining whether static resynchronization has finished and the received update data was provided by the host to the primary storage after the read time of static resynchronization, and only then clearing the progress queue and the update map.

5. A data storage system, comprising:

a primary digital data storage site, coupled to a host that provides write data to the primary storage site;

a backup digital data storage site;

a data mover coupled to the primary storage, backup storage, the data mover being programmed to mirror data stored at the primary storage site upon the backup storage site, where during predetermined error conditions the data mover stores data received by the storage system in the primary storage site without mirroring the data to the backup storage site, the data mover also being programmed to perform a method to resynchronization data of the backup data storage site with data of the primary data storage site comprising;

after termination of an error condition, the data mover performing a static resynchronization process comprising;

identifying data received during the error condition at the primary storage site without mirroring to the backup storage site;

reading the identified data from the primary storage site at one or more read times comprising;

repeatedly reading groups of the identified data until all identified data has been read; and

for each group of read data, storing indicia representing the read data in a progress queue along with a time of the reading;

writing the read data to the backup storage site; and

the primary storage site receiving update data from the host for storage while no error condition is occurring, the update data representing changes to data already existing on the primary storage site, and in response;

the data mover determining whether the static resynchronization process is in progress, and if not, copying the update data to the backup storage site;

if the static resynchronization process is in progress, the data mover determining whether the static resynchronization process is already processing data corresponding to the existing data, and if not, copying the update data to the backup storage site;

if the static resynchronization process is already processing data corresponding to the existing data, the data mover copying the update data to the backup storage site only if the host provided the update data to the primary storage site after the static resynchronization read time for the data already being processed comprising;

the data mover referencing the progress queue to determine the time of reading of the updated data;

the data mover copying the data to the backup storage site only if the host provided the updated data to the primary storage site after the time of reading of the updated data, otherwise discarding the updated data.

6. A data storage system, comprising:

a primary digital data storage site, coupled to a host that provides write data to the primary storage site;

a backup digital data storage site;

a data mover coupled to the primary storage, backup storage, the data mover being programmed to mirror data stored at the primary storage site upon the backup storage site, where during predetermined error conditions the data mover stores data received by the storage system in the primary storage site without mirroring the data to the backup storage site, the data mover also being programmed to perform a method to resynchronization data of the backup data storage site with data of the primary data storage site comprising;

after termination of an error condition, the data mover performing a static resynchronization process comprising;

identifying data received during the error condition at the primary storage site without mirroring to the backup storage site;

reading the identified data from the primary storage site at one or more read times comprising;

repeatedly reading groups of the identified data until all identified data has been read; and

for each group of read data, storing indicia representing the read data in a progress queue along with a time of the reading;

writing the read data to the backup storage site; and

the primary storage site receiving update data from the host for storage while no error condition is occurring, the update data representing changes to data already existing on the primary storage site, and in response;

the data mover determining whether the static resynchronization process is in progress, and if not, copying the update data to the backup storage site;

if the static resynchronization process is in progress, the data mover determining whether the static resynchronization process is already processing data corresponding to the existing data, and if not, copying the update data to the backup storage site;

if the static resynchronization process is already processing data corresponding to the existing data, the data mover copying the update data to the backup storage site only if the host provided the update data to the primary storage site after the static resynchronization read time for the data already being processed;

determining whether static resynchronization has finished and the received update data was provided by the host to the primary storage after the read time of static resynchronization, and only then clearing the progress queue and the update map.