FILE RETRIEVAL DURING A LEGACY STORAGE SYSTEM TO DISPERSED STORAGE NETWORK MIGRATION

• US 20120109885A1
• Filed: 10/04/2011
• Published: 05/03/2012
• Est. Priority Date: 11/01/2010
• Status: Abandoned Application

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Cleversafe Incorporated (International Business Machines Corporation)
• Inventors: GRUBE, GARY W., MARKISON, TIMOTHY W.
• Application Number:
  US13/252,418
• Publication Number:
  US 20120109885A1
• Time in Patent Office: Days
• US Class Current: 707/609
• CPC Class Codes: G06F 11/0727 in a storage system, e.g. in a DASD or network based storage system drivers for digital recording or reproducing units G06F3/06; circuits for error detection or correction within digital recording or reproducing units G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: G06F 16/972 Access to data in other repository systems, e.g. legacy data or dynamic Web page generation

Abstract

A method begins by a processing module receiving a retrieval request for a file and determining whether the file is being migrated from a legacy storage system to a dispersed error coding storage system. The method continues with the processing module determining a retrieval option for the file when the file is being migrated from the legacy storage system to the dispersed error coding storage system. The method continues with the processing module retrieving the file, based on the retrieval option, in at least one of a legacy format from the legacy storage system and a plurality of sets of encoded data slices from the dispersed error coding storage system.

Claims

1. A method comprises:

receiving a retrieval request for a file;

determining whether the file is being migrated from a legacy storage system to a dispersed error coding storage system;

when, the file is being migrated from the legacy storage system to the dispersed error coding storage system, determining a retrieval option for the file; and

based on the retrieval option, retrieving the file in at least one of;

a legacy format from the legacy storage system; and

a plurality of sets of encoded data slices from the dispersed error coding storage system.

2. The method of claim 1, wherein the determining whether the file is being migrated further comprises:

determining whether that the file is stored in a legacy format in the legacy storage system and is stored as a plurality of sets of encoded data slices in the dispersed error coding storage system.

3. The method of claim 1, wherein the retrieval option comprises at least one of:

retrieve the legacy format from the legacy storage system only;

retrieve the plurality of sets of encoded data slices from the dispersed error coding storage system only; and

retrieve both the legacy format from the legacy storage system and the plurality of sets of encoded data slices from the dispersed error coding storage system and outputting, based on first available, the legacy format or the plurality of sets of encoded data slices.

4. The method of claim 3 further comprises:

when retrieving the plurality of sets of encoded data slices, decoding the plurality of sets of encoded data slices to produce reconstructed data; and

outputting the reconstructed data in accordance with the retrieval option.

5. The method of claim 1 further comprises:

decoding the plurality of sets of encoded data slices to produce reconstructed data;

comparing the reconstructed data with the legacy format of the file; and

overwriting the legacy format of the file with the reconstructed data when the legacy format of the file does not substantially match the reconstructed data.

6. The method of claim 1 further comprises:

decoding the plurality of sets of encoded data slices to produce reconstructed data;

comparing the reconstructed data with the legacy format of the file;

deleting the legacy format of the file when the legacy format of the file substantially matches the reconstructed data; and

updating a data location table to indicate that the file is not stored in the legacy storage system.

7. The method of claim 1, wherein the determining the retrieval option for the file is based on at least one of:

a retrieval latency requirement;

a retrieval reliability requirement;

a memory availability requirement; and

a maximum bandwidth utilization requirement.

8. A computer comprises:

an interface;

a memory; and

a processing module operable to;

receive, via the interface, a retrieval request for a file;

determine whether the file is being migrated from a legacy storage system to a dispersed error coding storage system;

when, the file is being migrated from the legacy storage system to the dispersed error coding storage system, determine a retrieval option for the file; and

based on the retrieval option, retrieve, via the interface, the file in at least one of;

a legacy format from the legacy storage system; and

a plurality of sets of encoded data slices from the dispersed error coding storage system.

9. The computer of claim 8, wherein the processing module functions to determine whether the file is being migrated further by:

determining whether that the file is stored in a legacy format in the legacy storage system and is stored as a plurality of sets of encoded data slices in the dispersed error coding storage system.

10. The computer of claim 8, wherein the retrieval option comprises at least one of:

retrieve the legacy format from the legacy storage system only;

retrieve the plurality of sets of encoded data slices from the dispersed error coding storage system only; and

retrieve both the legacy format from the legacy storage system and the plurality of sets of encoded data slices from the dispersed error coding storage system and outputting, based on first available, the legacy format or the plurality of sets of encoded data slices.

11. The computer of claim 10, wherein the processing module further functions to:

when retrieving the plurality of sets of encoded data slices, decode the plurality of sets of encoded data slices to produce reconstructed data; and

output, via the interface, the reconstructed data in accordance with the retrieval option.

12. The computer of claim 8, wherein the processing module further functions to:

decode the plurality of sets of encoded data slices to produce reconstructed data;

compare the reconstructed data with the legacy format of the file; and

overwrite, via the interface, the legacy format of the file with the reconstructed data when the legacy format of the file does not substantially match the reconstructed data.

13. The computer of claim 8, wherein the processing module further functions to:

decode the plurality of sets of encoded data slices to produce reconstructed data;

compare the reconstructed data with the legacy format of the file;

delete the legacy format of the file when the legacy format of the file substantially matches the reconstructed data; and

update a data location table to indicate that the file is not stored in the legacy storage system.

14. The computer of claim 8, wherein the processing module functions to determine the retrieval option for the file based on at least one of:

a retrieval latency requirement;

a retrieval reliability requirement;

a memory availability requirement; and

a maximum bandwidth utilization requirement.