Increment resynchronization in hash-based replication

• US 10,152,527 B1
• Filed: 12/28/2015
• Issued: 12/11/2018
• Est. Priority Date: 12/28/2015
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Inventors: Meiri, David, Lempel, Irit
• Primary Examiner(s): Hasan, Syed H
• Application Number:
  US14/979,890
• Time in Patent Office: 1,079 Days
• CPC Class Codes: G06F 12/00 Accessing, addressing or allocating within memory systems or architectures digital input from, or digital output to record carriers, e.g. to disk storage units, G06F3/06
• CPC Class Codes: G06F 16/2255 Hash tables
• 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 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0641 De-duplication techniques
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

In one aspect, a method includes selecting a C-module; sending a write from a host to the selected C-module; selecting a D-module to commit a page related to the write; selecting a R-module to transmit data from the write to the target; writing the data from the write to target location; and writing the data to an address-to-hash table after acknowledgement that the data has been written to the target location and after the D-module acknowledges that the page is committed.

Claims

1. A method for storing data in a computer based data storage system, the computer based data storage system comprising a first storage subsystem and a second storage subsystem, the first storage subsystem being configured to store data in a consistency group of the first storage subsystem, and replicate the consistency group to the second storage subsystem, the method comprising:

receiving, at the first storage subsystem, a request to write a data payload;

storing the data payload in the consistency group of the first storage subsystem, the storing being performed by a module in the first storage subsystem;

initiating, by the module, a replication of the data payload to the second storage subsystem;

stopping all replication of the consistency group to the second storage subsystem in response to detecting that the replication of the data payload is unsuccessful;

synchronizing the first storage subsystem with the second storage subsystem; and

updating, by the module, at least one address-to-hash (A2H) table in the first storage subsystem to identify an address associated with the data payload after the first storage subsystem and the second storage subsystem are synchronized,

wherein the module is configured to update the A2H table after;

(i) the data payload has been stored in the consistency group of the first storage subsystem, and (ii) the module has received an acknowledgment that the data payload has been successfully replicated to the second storage subsystem.

2. The method of claim 1, wherein stopping all replication of the consistency group includes:

instructing the module to stop acknowledging write requests;

instructing the module to take a snapshot of the consistency group; and

notifying the module to stop the replication of the consistency group to the second storage subsystem.

3. The method of claim 2, wherein synchronizing the first storage subsystem with the second storage subsystem includes:

comparing data that is currently stored in the consistency group with the snapshot; and

sending any data that is currently stored in the consistency group and not identified in the snapshot to the second storage subsystem.

4. An apparatus for synchronous replication in a computer based data storage system, comprising:

one or more storage devices configured to implement a consistency group; and

electronic hardware circuitry that is operatively coupled to the one or more storage devices, the electronic hardware circuitry being configured to;

receive a request to write a data payload;

store the data payload in the consistency group;

initiate a replication of the data payload to a replication subsystem;

stop all replication of the consistency group to the replication subsystem in response to detecting that the replication of the data payload is unsuccessful;

synchronize the consistency group with a replica of the consistency group that is stored at the replication subsystem; and

update at least one address-to-hash (A2H) table in the first storage subsystem to identify an address associated with the data payload after the consistency group is synchronized with the replica of the consistency group, wherein the A2H table is updated after;

(i) the data payload has been stored in the consistency group, and (ii) the data payload has been successfully replicated to the replication subsystem.

5. The apparatus of claim 4, wherein the electronic hardware circuitry comprises at least one of a processor, a memory, a programmable logic device or a logic gate.

6. The apparatus of claim 4, further comprising taking a snapshot of the consistency group when the replication of the consistency group is stopped.

7. The apparatus of claim 6, wherein synchronizing the consistency group with the replica of the consistency group includes:

comparing data that is currently stored in the consistency group with the snapshot; and

sending any data that is currently stored in the consistency group and not identified in the snapshot to the replication subsystem.

8. A non-transitory computer-readable medium storing one or more processor-executable instructions, which executed by one or more processors, cause the one or more processors to perform a method for storing data in a computer based data storage system, the computer based data storage system comprising a first storage subsystem and a second storage subsystem, the first storage subsystem being configured to store data in a consistency group of the first storage subsystem, and replicate the consistency group to the second storage subsystem, the method comprising:

receiving, at the first storage subsystem, a request to write a data payload;

storing the data payload in the consistency group of the first storage subsystem, the storing being performed by a module in the first storage subsystem;

initiating, by the module, a replication of the data payload to the second storage subsystem;

stopping all replication of the consistency group to the second storage subsystem in response to detecting that the replication of the data payload is unsuccessful;

synchronizing the first storage subsystem with the second storage subsystem; and

updating, by the module, at least one address-to-hash (A2H) table in the first storage subsystem to identify an address associated with the data payload after the first storage subsystem and the second storage subsystem are synchronized,

wherein the module is configured to update the A2H table after;

(i) the data payload has been stored in the consistency group of the first storage subsystem, and (ii) the module has received an acknowledgment that the data payload has been successfully replicated to the second storage subsystem.

9. The non-transitory computer-readable medium of claim 8, wherein stopping all replication of the consistency group includes:

instructing the module to stop acknowledging write requests;

instructing the module to take a snapshot of the consistency group; and

notifying the module to stop the replication of the consistency group to the second storage subsystem.

10. The non-transitory computer-readable medium of claim 9, wherein synchronizing the first storage subsystem with the second storage subsystem includes:

comparing data that is currently stored in the consistency group with the snapshot; and

sending any data that is currently stored in the consistency group and not identified in the snapshot to the second storage subsystem.