UTILIZING UNMAPPED AND UNKNOWN STATES IN A REPLICATED STORAGE SYSTEM

• US 20160098199A1
• Filed: 10/07/2014
• Published: 04/07/2016
• Est. Priority Date: 10/07/2014
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Pure Storage, Inc.
• Inventors: Golden, Christopher, Colgrove, John, Miller, Ethan L., Sharpe, Malcolm, Hodgson, Steve
• Granted Patent: US 9,489,132 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/1009 using page tables, e.g. page table structures
• CPC Class Codes: G06F 2212/1056 Simplification
• CPC Class Codes: G06F 2212/214 Solid state disk
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 3/0604 Improving or facilitating administration, e.g. storage management
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0683 Plurality of storage devices
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays

Abstract

A system and method for utilizing unmapped and unknown states in a storage system. When a first portion of a first medium is determined to be unreachable from any other mediums, the first portion of the first medium may be put into an unmapped state, and its data may be discarded and the corresponding storage locations may be freed. During replication of the first medium to a replica storage array, the state of the first portion of the first medium may be translated from the unmapped state into an unknown state on the replica storage array. If another storage array has the data of the first portion of the first medium, this data may be used to overwrite the first portion of the first medium on the replica storage array, converting the first portion of the first medium from the unknown state into the mapped state.

Claims

1. A system comprising:

a first storage subsystem; and

a second storage subsystem;

wherein the system is configured to;

detect a request to replicate a first medium from the first storage subsystem to the second storage subsystem;

determine that a first portion of the first medium is in a first state on the first storage subsystem;

record that the first portion of the first medium is in a second state on the second storage subsystem, wherein the second state is different from the first state.

2. The system as recited in claim 1, wherein the first state is an unmapped state, and wherein the second state is an unknown state.

3. The system as recited in claim 2, wherein the system is further configured to:

determine where to record that the first portion of the first medium is in the unknown state based on a size of the first portion;

record that the first portion of the first medium is in the unknown state in a first table responsive to determining the size of the first portion is less than a first programmable threshold; and

record that the first portion of the first medium is in the unknown state in a second table responsive to determining the size of the first portion is greater than the first programmable threshold.

4. The system as recited in claim 3, wherein the first table is an address translation table, and wherein the second table is a medium mapping table.

5. The system as recited in claim 2, wherein the system is further configured to:

determine where to record that the first portion of the first medium is in the unknown state based on locations of endpoints of the first portion;

record that the first portion of the first medium is in the unknown state in a first table responsive to determining the endpoints of the first portion are not on sector range boundaries; and

record that the first portion of the first medium is in the unknown state in a second table responsive to determining the endpoints are on sector range boundaries.

6. The system as recited in claim 2, wherein the system is further configured to:

detect a request to replicate a second medium;

create a first tuple in the unknown state for the second medium in its entirety prior to receiving any portion of the second medium; and

store the first tuple in a first table.

7. The system as recited in claim 6, wherein the system is further configured to:

detect a user operation targeting a first portion of the second medium;

generate a request for the first portion of the second medium to a corresponding storage subsystem;

receive the first portion of the second medium from the corresponding storage subsystem;

create a second tuple in a mapped state, wherein the second tuple corresponds to the first portion of the second medium; and

store the second tuple in the first table.

8. A method comprising:

detecting a request to replicate a first medium from a first storage subsystem to a second storage subsystem;

receiving an indication that a first portion of the first medium is in a first state on the first storage subsystem; and

recording that the first portion of the first medium is in the second state on the second storage subsystem, wherein the second state is different from the first state.

9. The method as recited in claim 8, wherein the first state is an unmapped state, and wherein the second state is an unknown state.

10. The method as recited in claim 9, further comprising:

determining where to record that the first portion of the first medium is in the unknown state based on a size of the first portion;

recording that the first portion of the first medium is in the unknown state in a first table responsive to determining the size of the first portion is less than a first programmable threshold; and

recording that the first portion of the first medium is in the unknown state in a second table responsive to determining the size of the first portion is greater than the first programmable threshold.

11. The method as recited in claim 10, wherein the first table is an address translation table, and wherein the second table is a medium mapping table.

12. The method as recited in claim 9, further comprising:

determining where to record that the first portion of the first medium is in the unknown state based on locations of endpoints of the first portion;

recording that the first portion of the first medium is in the unknown state in a first table responsive to determining the endpoints of the first portion are not on sector range boundaries; and

recording that the first portion of the first medium is in the unknown state in a second table responsive to determining the endpoints are on sector range boundaries.

13. The method as recited in claim 9, further comprising:

detecting a request to replicate a second medium;

creating a first tuple in the unknown state for the second medium in its entirety prior to receiving any portion of the second medium; and

storing the first tuple in a first table.

14. The method as recited in claim 8, further comprising:

detecting a user operation targeting a first portion of the second medium;

generating a request for the first portion of the second medium to a corresponding storage subsystem;

receiving the first portion of the second medium from the corresponding storage subsystem;

creating a second tuple in a mapped state, wherein the second tuple corresponds to the first portion of the second medium; and

storing the second tuple in the first table.

15. A non-transitory computer readable storage medium storing program instructions, wherein the program instructions are executable by a processor to:

detect a request to replicate a first medium from a first storage subsystem to a second storage subsystem;

receive an indication that a first portion of the first medium is in a first state on the first storage subsystem; and

record that the first portion of the first medium is in the second state on the second storage subsystem, wherein the second state is different from the first state.

16. The non-transitory computer readable storage medium as recited in claim 15, wherein the first state is an unmapped state, and wherein the second state is an unknown state.

17. The non-transitory computer readable storage medium as recited in claim 16, wherein the program instructions are further executable by a processor to:

determine where to record that the first portion of the first medium is in the unknown state based on a size of the first portion;

record that the first portion of the first medium is in the unknown state in a first table responsive to determining the size of the first portion is less than a first programmable threshold; and

record that the first portion of the first medium is in the unknown state in a second table responsive to determining the size of the first portion is greater than the first programmable threshold.

18. The non-transitory computer readable storage medium as recited in claim 17, wherein the first table is an address translation table, and wherein the second table is a medium mapping table.

19. The non-transitory computer readable storage medium as recited in claim 16, wherein the program instructions are further executable by a processor to:

determine where to record that the first portion of the first medium is in the unknown state based on locations of endpoints of the first portion;

record that the first portion of the first medium is in the unknown state in a first table responsive to determining the endpoints of the first portion are not on sector range boundaries; and

record that the first portion of the first medium is in the unknown state in a second table responsive to determining the endpoints are on sector range boundaries.

20. The non-transitory computer readable storage medium as recited in claim 16, wherein the program instructions are further executable by a processor to:

detect a request to replicate a second medium;

create a first tuple in the unknown state for the second medium in its entirety prior to receiving any portion of the second medium; and

store the first tuple in a first table.