Replication and snapshots for flash storage systems

• US 10,346,084 B1
• Filed: 11/06/2017
• Issued: 07/09/2019
• Est. Priority Date: 06/25/2014
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Pure Storage, Inc.
• Inventors: Golden, Christopher, Cao, Jianting, Grunwald, David, Sharpe, Malcolm, Hodgson, Steve
• Primary Examiner(s): Mackes, Kris E
• Assistant Examiner(s): Bui, Tiffany Thuy
• Application Number:
  US15/804,402
• Time in Patent Office: 610 Days
• CPC Class Codes: G06F 11/1658 Data re-synchronization of a redundant component, or initial sync of replacement, additional or spare unit
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 16/27 Replication, distribution or synchronisation of data between databases or within a distributed database system; Distributed database system architectures therefor
• CPC Class Codes: G06F 3/06 Digital input from, or digital output to, record carriers , e.g. RAID, emulated record carriers or networked record carriers
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0614 Improving the reliability of storage systems
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 3/0683 Plurality of storage devices
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

A system and method for exposing volumes with underlying read-write mediums to user operations. When a medium is in the process of being replicated to a storage array, a volume which relies on the medium can be exposed to user operations (e.g., snapshots, read and write operations) once the portions of the medium which underlie the volume have been replicated. The volume can be exposed to user operations while one or more other portions of the medium are unfilled and while the medium is in an intermediate read-write state.

Claims

1. A storage system comprising:

one or more storage controllers; and

a plurality of storage devices, wherein the plurality of storage devices store a dataset;

wherein the one or more storage controllers are configured to;

receive a request to replicate the dataset onto another storage system;

identify one or more snapshots that contain data that is included within the dataset, wherein each of the one or more snapshots further include data that is not included within the dataset; and

replicate, onto the other storage system, portions of the one or more snapshots that contain data that is included within the dataset;

wherein each snapshot is implemented based at least in part on one or more metadata objects corresponding to the dataset,

wherein the dataset is exposed to one or more user operations after a portion of the one or more metadata objects is replicated from the storage system to the other storage system and prior to other portions of the one or more metadata objects being replicated from the storage system to the other storage system, and

wherein the storage system is configured to wait until the other portions of the one or more metadata objects have been replicated before putting the one or more metadata objects into a read-only state.

2. The system as recited in claim 1, wherein the storage system is further configured to prevent second data from being exposed to one or more user operations prior to a second portion of the one or more metadata objects being replicated from the storage system to the other storage system, wherein the second portion of the one or more metadata objects underlies the second data.

3. The system as recited in claim 2, wherein the dataset is a volume, and wherein the storage system is configured to take a snapshot of the volume while the one or more metadata objects are in a read-write state.

4. The system as recited in claim 2, wherein the storage system is configured to perform a write operation to the dataset while the one or more metadata objects are in a read-write state.

5. The system as recited in claim 2, wherein the dataset is mapped to an anchor metadata object, wherein a first portion of the anchor metadata object is mapped to the first portion of the metadata object, and wherein the storage system is configured to write to other portions of the metadata object while the dataset is exposed to one or more user operations.

6. A method comprising:

receiving a request to replicate the dataset onto another storage system;

identify one or more snapshots that contain data that is included within the dataset, wherein each of the one or more snapshots further include data that is not included within the dataset; and

replicate, onto the other storage system, portions of the one or more snapshots that contain data that is included within the dataset;

wherein each snapshot is implemented based at least in part on one or more metadata objects corresponding to the dataset,

wherein the dataset is exposed to one or more user operations after a portion of the one or more metadata objects is replicated from the storage system to the other storage system and prior to other portions of the one or more metadata objects being replicated from the storage system to the other storage system, and

wherein the storage system is configured to wait until the other portions of the one or more metadata objects have been replicated before putting the one or more metadata objects into a read-only state.

7. The method as recited in claim 6, further comprising preventing second data from being exposed to one or more user operations prior to a second portion of the one or more metadata objects being replicated from the storage system to the other storage system, wherein the second portion of the one or more metadata objects underlies the second data.

8. The method as recited in claim 7, wherein the dataset is a volume, and wherein the storage system is configured to take a snapshot of the volume while the one or more metadata objects are in a read-write state.

9. The method as recited in claim 7, further comprising performing a write operation to the dataset while the one or more metadata objects are in a read-write state.

10. The method as recited in claim 7, wherein the dataset is mapped to an anchor metadata object, wherein a first portion of the anchor metadata object is mapped to the first portion of the metadata object, and wherein the storage system is configured to write to other portions of the metadata object while the dataset is exposed to one or more user operations.

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

receive a request to replicate the dataset onto another storage system;

identify one or more snapshots that contain data that is included within the dataset, wherein each of the one or more snapshots further include data that is not included within the dataset; and

replicate, onto the other storage system, portions of the one or more snapshots that contain data that is included within the dataset;

wherein each snapshot is implemented based at least in part on one or more metadata objects corresponding to the dataset,

wherein the dataset is exposed to one or more user operations after a portion of the one or more metadata objects is replicated from the storage system to the other storage system and prior to other portions of the one or more metadata objects being replicated from the storage system to the other storage system, and

wherein the storage system is configured to wait until the other portions of the one or more metadata objects have been replicated before putting the one or more metadata objects into a read-only state.

12. The non-transitory computer readable storage medium as recited in claim 11, wherein the program instructions are further executable by a processor to prevent second data from being exposed to one or more user operations prior to a second portion of the one or more metadata objects being replicated from the storage system to the other storage system, wherein the second portion of the one or more metadata objects underlies the second data.

13. The non-transitory computer readable storage medium as recited in claim 12, wherein the dataset is a volume, and wherein the storage system is configured to take a snapshot of the volume while the one or more metadata objects are in a read-write state.

14. The non-transitory computer readable storage medium as recited in claim 12, wherein the storage system is configured to perform a write operation to the dataset while the one or more metadata objects are in a read-write state.