Point-in-time copies in a cascade using maps and fdisks

• US 8,713,272 B2
• Filed: 05/17/2012
• Issued: 04/29/2014
• Est. Priority Date: 10/30/2008
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Agombar, John P., Beeken, Christopher B., Fuente, Carlos F., Scales, William J.
• Primary Examiner(s): BRADLEY, MATTHEW A
• Application Number:
  US13/474,647
• Publication Number:
  US 20120226879A1
• Time in Patent Office: 712 Days
• Field of Search: 711/61, 711/162, 711/E12.103, 707640-660
• US Class Current: 711/162
• CPC Class Codes: G06F 11/1662 the resynchronized component or unit being a persistent storage device re-synchronization of failed mirror storage G06F11/2082; rebuild or reconstruction of parity RAID storage G06F11/1008
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 16/20 of structured data, e.g. relational data

Abstract

A technique for handling a FlashCopy® process includes receiving a FlashCopy® instruction for a source disk, performing a FlashCopy® point in time copy of the source disk on to a target disk, creating a map specifying the FlashCopy® point in time copy from the source disk to the target disk, creating a primary fdisk for the source disk, if one does not already exist, and creating a primary fdisk for the target disk, if one does not already exist, or, if one does already exist, converting the existing primary fdisk for the target disk into a secondary fdisk, and creating a new primary fdisk for the target disk.

Claims

1. A method of handling a copy process comprising:

for a point in time copy from a source disk to a target disk that are part of a cascade of disks, wherein the cascade represents a series of point in time copies between the disks, creating a map specifying the point in time copy from the source disk to the target disk;

in response to determining that a primary fdisk does not exist for the source disk, creating the primary fdisk for the source disk, wherein the primary fdisk for the source disk comprises an object that links the source disk to maps upstream and downstream within the cascade;

in response to determining that a primary fdisk does not exist for the target disk, creating the primary fdisk for the target disk, wherein the primary fdisk for the target disk comprises an object that links the target disk to maps upstream and downstream within the cascade; and

in response to determining that the primary fdisk for the target disk does exist,

converting the existing primary fdisk for the target disk into a secondary fdisk; and

creating a new primary fdisk for the target disk.

2. The method according to claim 1, further comprising:

linking the created map to the primary fdisk for the source disk and the primary fdisk for the target disk in the cascade.

3. The method according to claim 2, further comprising:

receiving an IO command for the source disk; and

processing the IO command according to a predefined set of rules relating to the existence of primary and secondary fdisks for the source disk.

4. The method according to claim 3, wherein the predefined set of rules define cleaning of the secondary fdisk prior to processing the IO command, and wherein the cleaning comprises:

copying data from the source disk to the target disk defined in the map linked to a secondary disk.

5. The method of claim 1, wherein at least one target disk among the disks from an earlier point in time copy becomes a source disk for a new point in time copy.

6. The method of claim 1, wherein the source disk is represented in multiple cascades with different fdisks.

7. The method of claim 1, wherein the source disk is represented at different positions within the cascade with different fdisks.