Coordinating write sequences in a data storage system

• US 8,849,939 B2
• Filed: 12/02/2011
• Issued: 09/30/2014
• Est. Priority Date: 12/02/2011
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Wilkinson, John P.
• Primary Examiner(s): Gilles, Jude Jean
• Application Number:
  US13/309,587
• Publication Number:
  US 20130145117A1
• Time in Patent Office: 1,033 Days
• Field of Search: 711/167, 711/124, 711/114, 711/154, 711/162, 711/100, 711/112, 711/113, 711/148
• US Class Current: 709/212
• CPC Class Codes: G06F 11/2064 while ensuring consistency
• CPC Class Codes: G06F 11/2071 using a plurality of controllers

Abstract

According to one aspect of the present disclosure, a system and technique for coordinating write sequences in a data storage system includes a processor configured to receive from a primary device, responsive to the primary device receiving a request to write to primary storage, a request for a sequence number. The system also includes a sequence generator configured to: generate a current sequence number for the write; generate a first identifier indicating an identity of secondary devices writing to secondary storage based on the current sequence number; generate a second identifier indicating an identity of secondary devices writing to secondary storage based on the current sequence number and a previous sequence number; transmit the current sequence number and the second identifier to the primary device; and transmit the current sequence number and the first identifier to the secondary devices writing to secondary storage based on the previous sequence number.

Claims

1. A system for coordinated sequencing of writes, comprising:

an input/output (JO) processor configured to receive from a primary device, responsive to the primary device receiving a request to write to primary storage, a request for a sequence number; and

a sequence generator configured to;

generate a current sequence number for the write;

generate a first identifier indicating an identity of secondary devices writing to secondary storage based on the current sequence number;

generate a second identifier indicating an identity of secondary devices writing to secondary storage based on the current sequence number and a previous sequence number;

transmit the current sequence number and the second identifier to the primary device; and

transmit the current sequence number and the first identifier to the secondary devices writing to secondary storage based on the previous sequence number.

2. The system of claim 1, wherein the primary device is configured to transmit to secondary devices writing to secondary storage based on the current sequence number the write, the current sequence number, and the second identifier.

3. The system of claim 2, wherein the secondary devices writing to secondary storage based on the previous sequence number are configured to transmit to secondary devices writing to secondary storage based on the current sequence number a write done message indicating completion of a write based on the previous sequence number.

4. The system of claim 1, wherein the first identifier comprises as a bit vector, wherein each bit position of the bit vector corresponds to a particular secondary device.

5. The system of claim 1, wherein the first and second identifiers comprise bit vectors, wherein each bit position of a respective bit vector corresponds to a particular secondary device.

6. The system of claim 4, wherein the bit vector comprises a quantity of bits corresponding to a quantity of secondary devices.

7. The system of claim 3, wherein, responsive to the secondary device receiving the write done message from each secondary device writing to secondary storage based on the previous sequence number, committing the write for the current sequence number to secondary storage.

8. A computer program product for coordinated sequencing of writes, the computer program product comprising:

a computer readable storage medium having computer readable program code embodied therewith, the computer readable program code comprising computer readable program code configured to;

responsive to a primary device receiving a request to write to primary storage, receive from the primary device a request for a sequence number;

generate a current sequence number for the write;

generate a first identifier indicating an identity of secondary devices writing to secondary storage based on the current sequence number;

generate a second identifier indicating an identity of secondary devices writing to secondary storage based on the current sequence number and a previous sequence number;

transmit the current sequence number and the second identifier to the primary device; and

transmit the current sequence number and the first identifier to the secondary devices writing to secondary storage based on the previous sequence number.

9. The computer program product of claim 8, wherein the computer readable program code is configured to cause the primary device to transmit to secondary devices writing to secondary storage based on the current sequence number the write, the current sequence number, and the second identifier.

10. The computer program product of claim 9, wherein the computer readable program code is configured to cause the secondary devices writing to secondary storage based on the previous sequence number to transmit to secondary devices writing to secondary storage based on the current sequence number a write done message indicating completion of a write based on the previous sequence number.

11. The computer program product of claim 8, wherein the computer readable program code is configured to configure the first identifier as a bit vector, wherein each bit position of the bit vector corresponds to a particular secondary device.

12. The computer program product of claim 11, wherein the computer readable program code is configured to configure the bit vector having a quantity of bits corresponding to a quantity of secondary devices.