Asynchronous mirror inconsistency correction

Patent metadata

Field	Value
Publication number	US-2018210781-A1
Application number	US-201715411983-A
Country	US
Kind code	A1
Filing date	Jan 21, 2017
Priority date	Jan 21, 2017
Publication date	Jul 26, 2018
Grant date	—

Abstract

A method for correcting data inconsistency in an asynchronous data replication environment is disclosed. In one embodiment, such a method includes detecting an error on a secondary track of a secondary volume, wherein the secondary volume is in a mirroring relationship with a primary volume. In response to detecting the error, the method flags the secondary track as “temporarily inconsistent.” The method then issues a command to read a corresponding primary track from the primary volume, records a time when the primary track was read, and mirrors the primary track and time to the secondary volume. The method then applies, to the secondary track, updates to the secondary track having a timestamp earlier than the time, and applies the primary track to the secondary track. The method then unflags the secondary track as “temporarily inconsistent.” A corresponding system and computer program product are also disclosed.

First claim

1 . A method for correcting data inconsistency in an asynchronous data replication environment, the method comprising:
detecting an error on a secondary track of a secondary volume, wherein the secondary volume is in a mirroring relationship with a primary volume; flagging the secondary track as “temporarily inconsistent”; issuing a command to read a corresponding primary track from the primary volume, recording a time when the primary track was read, and mirroring the primary track and time to the secondary volume; applying, to the secondary track, updates to the secondary track having a timestamp earlier than the time; applying the primary track to the secondary track after the updates have been applied; and unflagging the secondary track as “temporarily inconsistent”.

2 . The method of claim 1 , wherein mirroring the primary track and time to the secondary volume comprises placing the primary track and time in a sidefile queue associated with the primary volume.

3 . The method of claim 2 , wherein the sidefile queue contains data for replication from the primary volume to the secondary volume.

4 . The method of claim 1 , wherein mirroring the primary track and time to the secondary volume comprises asynchronously mirroring the primary track and time to the secondary volume.

5 . The method of claim 1 , wherein detecting the error further comprises initiating a scan of the secondary volume for other errors.

6 . The method of claim 1 , wherein flagging the secondary track as “temporarily inconsistent” comprises flagging the entire secondary volume as “temporarily inconsistent”.

7 . The method of claim 1 , further comprising forming a consistency group after applying the primary track to the secondary track.

8 . A computer program product for correcting data inconsistency in an asynchronous data replication environment, the computer program product comprising a non-transitory computer-readable storage medium having computer-usable program code embodied therein, the computer-usable program code configured to perform the following when executed by at least one processor:
detect an error on a secondary track of a secondary volume, wherein the secondary volume is in a mirroring relationship with a primary volume; flag the secondary track as “temporarily inconsistent”; issue a command to read a corresponding primary track from the primary volume, record a time when the primary track was read, and mirror the primary track and time to the secondary volume; apply, to the secondary track, updates to the secondary track having a timestamp earlier than the time; apply the primary track to the secondary track after the updates have been applied; and unflag the secondary track as “temporarily inconsistent”.

9 . The computer program product of claim 8 , wherein mirroring the primary track and time to the secondary volume comprises placing the primary track and time in a sidefile queue associated with the primary volume.

10 . The computer program product of claim 9 , wherein the sidefile queue contains data for replication from the primary volume to the secondary volume.

11 . The computer program product of claim 8 , wherein mirroring the primary track and time to the secondary volume comprises asynchronously mirroring the primary track and time to the secondary volume.

12 . The computer program product of claim 8 , wherein detecting the error further comprises initiating a scan of the secondary volume for other errors.

13 . The computer program product of claim 8 , wherein flagging the secondary track as “temporarily inconsistent” comprises flagging the entire secondary volume as “temporarily inconsistent”.

14 . The computer program product of claim 8 , wherein the computer-usable program code is further configured to form a consistency group after applying the primary track to the secondary track.

15 . A system for correcting data inconsistency in an asynchronous data replication environment, the system comprising:
at least one processor; at least one memory device operably coupled to the at least one processor and storing instructions for execution on the at least one processor, the instructions causing the at least one processor to:
detect an error on a secondary track of a secondary volume, wherein the secondary volume is in a mirroring relationship with a primary volume;
flag the secondary track as “temporarily inconsistent”;
issue a command to read a corresponding primary track from the primary volume, record a time when the primary track was read, and mirror the primary track and time to the secondary volume;
apply, to the secondary track, updates to the secondary track having a timestamp earlier than the time;
apply the primary track to the secondary track after the updates have been applied; and
unflag the secondary track as “temporarily inconsistent”.

16 . The system of claim 15 , wherein mirroring the primary track and time to the secondary volume comprises placing the primary track and time in a sidefile queue associated with the primary volume.

17 . The system of claim 16 , wherein the sidefile queue contains data for replication from the primary volume to the secondary volume.

18 . The system of claim 15 , wherein detecting the error further comprises initiating a scan of the secondary volume for other errors.

19 . The system of claim 15 , wherein flagging the secondary track as “temporarily inconsistent” comprises flagging the entire secondary volume as “temporarily inconsistent”.

20 . The system of claim 15 , wherein the instructions further cause the at least one processor to form a consistency group after applying the primary track to the secondary track.

Assignees

• IBM

Inventors

• Mcbride Gregory E
• Reed David C
• Stanley Warren K

Classifications

• G06F11/2005

  using redundant communication controllers · CPC title

• G06F11/0793 Primary

  Remedial or corrective actions (recovery from an exception in an instruction pipeline G06F9/3861; by retry G06F11/1402; for recovering from a failure of a protocol instance or entity H04L69/40) · CPC title

• G06F11/0772

  Means for error signaling, e.g. using interrupts, exception flags, dedicated error registers · CPC title

• G06F11/0727

  in a storage system, e.g. in a DASD or network based storage system (drivers for digital recording or reproducing units G06F3/06; circuits for error detection or correction within digital recording or reproducing units G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097) · CPC title

• G06F11/079

  Root cause analysis, i.e. error or fault diagnosis (in a hardware test environment G06F11/22; in a software test environment G06F11/36) · CPC title