Mirroring write operations across data storage devices

Patent metadata

Field	Value
Publication number	US-10922009-B2
Application number	US-201916505453-A
Country	US
Kind code	B2
Filing date	Jul 8, 2019
Priority date	Jul 8, 2019
Publication date	Feb 16, 2021
Grant date	Feb 16, 2021

Abstract

A computer-implemented method, according to one approach, includes: receiving a first request to perform a write operation from a host, and performing the write operation. Metadata corresponding to the first request is sent to the secondary data storage device, and metadata corresponding to a second request to perform the write operation is received from the secondary data storage device, where the second request was received at the secondary data storage device from the host. The metadata corresponding to the first and second requests is used to determine whether the write operation has been mirrored across the primary and secondary data storage devices. In response to determining that the write operation has been mirrored across the primary and secondary data storage devices, a response is sent to the secondary data storage device which indicates that the write operation has been reconciled across the primary and secondary data storage devices.

First claim

What is claimed is:

1. A computer-implemented method for mirroring write operations across primary and secondary data storage devices, comprising:
receiving a first request to perform a write operation from a host;
performing the write operation;
sending metadata corresponding to the first request to the secondary data storage device;
receiving metadata corresponding to a second request to perform the write operation from the secondary data storage device, wherein the second request was received at the secondary data storage device from the host;
using the metadata corresponding to the first and second requests to determine whether the write operation has been mirrored across the primary and secondary data storage devices; and
in response to determining that the write operation has been mirrored across the primary and secondary data storage devices, sending a response to the secondary data storage device which indicates that the write operation has been reconciled across the primary and secondary data storage devices.

2. The computer-implemented method of claim 1 , comprising:
receiving a response from the secondary data storage device which indicates that the write operation has been reconciled across the primary and secondary data storage devices in response to the secondary data storage device determining that the write operation has been mirrored across the primary and secondary data storage devices,
wherein the secondary data storage device performs the write operation in response to receiving the second request to perform the write operation,
wherein the secondary data storage device uses the metadata corresponding to the first and second requests to determine whether the write operation has been reconciled across the primary and secondary data storage devices.

3. The computer-implemented method of claim 1 , comprising:
receiving a read request;
determining whether data specified in the read request has been reconciled across the primary and secondary data storage devices;
in response to determining that the data specified in the read request has not been reconciled across the primary and secondary data storage devices, delaying performance of the read request; and
in response to determining that the data specified in the read request has been reconciled across the primary and secondary data storage devices, performing the read request.

4. The computer-implemented method of claim 1 , comprising:
sending a response to the host which indicates that the write operation has been performed prior to determining whether the write operation has been reconciled across the primary and secondary data storage devices.

5. The computer-implemented method of claim 1 , wherein the metadata corresponding to the first request includes information selected from the group consisting of: a timestamp, hash values, and storage location identification, wherein the metadata corresponding to the second request includes information selected from the group consisting of: a timestamp, hash values, and storage location identification.

6. The computer-implemented method of claim 1 , comprising:
storing the metadata corresponding to the first request in memory,
wherein the metadata corresponding to the first request is overwritten by metadata corresponding to a subsequent request to perform a write operation on a same record as the first request.

7. The computer-implemented method of claim 1 , wherein the using the metadata corresponding to the first and second requests to determine whether the write operation has been mirrored across the primary and secondary data storage devices is performed for all write operation requests received from the host.

8. A computer program product for mirroring write operations across primary and secondary data storage devices, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions readable and/or executable by a processor to cause the processor to:
receive, by the processor, a first request to perform a write operation from a host;
perform, by the processor, the write operation;
send, by the processor, metadata corresponding to the first request to the secondary data storage device;
receive, by the processor, metadata corresponding to a second request to perform the write operation from the secondary data storage device, wherein the second request was received at the secondary data storage device from the host;
use, by the processor, the metadata corresponding to the first and second requests to determine whether the write operation has been mirrored across the primary and secondary data storage devices; and
in response to determining that the write operation has been mirrored across the primary and secondary data storage devices, send, by the processor, a response to the secondary data storage device which indicates that the write operation has been reconciled across the primary and secondary data storage devices.

9. The computer program product of claim 8 , the program instructions readable and/or executable by the processor to cause the processor to:
receive, by the processor, a response from the secondary data storage device which indicates that the write operation has been reconciled across the primary and secondary data storage devices in response to the secondary data storage device determining that the write operation has been mirrored across the primary and secondary data storage devices,
wherein the secondary data storage device performs the write operation in response to receiving the second request to perform the write operation,
wherein the secondary data storage device uses the metadata corresponding to the first and second requests to determine whether the write operation has been mirrored across the primary and secondary data storage devices.

10. The computer program product of claim 8 , the program instructions readable and/or executable by the processor to cause the processor to:
receive, by the processor, a read request;
determine, by the processor, whether data specified in the read request has been reconciled across the primary and secondary data storage devices;
in response to determining that the data specified in the read request has not been reconciled across the primary and secondary data storage devices, delay, by the processor, performance of the read request; and
in response to determining that the data specified in the read request has been reconciled across the primary and secondary data storage devices, perform, by the processor, the read request.

11. The computer program product of claim 8 , the program instructions readable and/or executable by the processor to cause the processor to:
send, by the processor, a response to the host which indicates that the write operation has been performed prior to determining whether the write operation has been mirrored across the primary and secondary data storage devices.

12. The computer program product of claim 8 , wherein the metadata corresponding to the first request includes information selected from the group consisting of: a timestamp, hash values, and storage location identification, wherein the metadata corresponding to the second request includes information selected from the group consisting of: a timestamp, hash values, and storage location identification.

13. The computer program product of claim 8 , the program instructions readable and/or executable by the processor to cause the processor to:
store, by the processor, the metadata corresponding to the first request in memory,
wherein the metadata corresponding to the first request is

Assignees

• IBM

Inventors

• Yudenfriend Harry M
• Sutton Peter Grimm
• Compton Scott B

Classifications

• G06F3/067 Primary

  Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS] · CPC title

• G06F3/0659

  Command handling arrangements, e.g. command buffers, queues, command scheduling · CPC title

• G06F3/065 Primary

  Replication mechanisms · CPC title

• G06F3/061

  Improving I/O performance · CPC title

• G06F3/0613

  in relation to throughput · CPC title