Creating replicas at user-defined points in time

Patent metadata

Field	Value
Publication number	US-2017192857-A1
Application number	US-201514984334-A
Country	US
Kind code	A1
Filing date	Dec 30, 2015
Priority date	Dec 30, 2015
Publication date	Jul 6, 2017
Grant date	—

Abstract

Example embodiments of the present invention relate to methods, systems, and computer program products for determining replicas for removal from a plurality of replicas as defined in a data retention policy. The method includes performing asynchronous replication from a source to a target according to time-based replication cycles. A retention policy then may be identified defining a number of asynchronous replication replicas to retain and a plurality of associated periods which then may be retained according to the policy.

First claim

What is claimed is:

1 . A method comprising:
performing asynchronous replication from a source to a target according to time-based replication cycles; identifying a retention policy defining a number of asynchronous replication replicas to retain and a plurality of associated periods; and retaining asynchronous replication replicas according to the policy.

2 . The method of claim 1 wherein identifying a retention policy defining a number of asynchronous replication replicas to retain and a plurality of associated periods comprises defining each successive period in the plurality of periods as a multiple of an immediately preceding period in the plurality of periods.

3 . The method of claim 2 wherein retaining asynchronous replication replicas according to the policy comprises retaining, for each successive period, a number of asynchronous replication replicas from the immediately preceding period in the plurality of periods.

4 . The method of claim 3 wherein a first period among the plurality of periods defines a minimal lag establishing a lower threshold of time between asynchronous replication cycles derived from a Recovery Point Objective defining a maximum amount of permitted data loss associated with recovery from the target.

5 . The method of claim 1 wherein performing asynchronous replication from a source to a target according to time-based replication cycles comprises, at a source side:
for each asynchronous replication cycle of a first level having a position in a series of replication cycles equal to a first multiple of a ratio of a first period and a second period, marking the asynchronous replication cycle of the first level as an asynchronous replication cycle of a second level; and
for each asynchronous replication cycle of the of the second level having a position in the series of replication cycles equal to a second multiple of a ratio of the second period and a third period, marking the asynchronous replication cycle of the second level as an asynchronous replication cycle of a third level.

6 . The method of claim 5 further comprising, at a target side:
preserving each asynchronous replication cycle marked as the second level for the second period; and
preserving each asynchronous replication cycle marked as the third level for the third period.

7 . The method of claim 5 further comprising, for asynchronous replication cycles having a transmission time exceeding the first period, determining a time of a next asynchronous replication cycle switch.

8 . The method of claim 7 wherein determining a time of a next asynchronous cycle switch comprises, if the asynchronous replication cycle transmission time is less than or equal to the difference between the second period and the first period, starting the next asynchronous replication cycle.

9 . The method of claim 7 wherein determining a time of a next asynchronous cycle switch comprises, if the asynchronous replication cycle transmission time is greater than the difference between the second period and the first period less than the second period:
waiting until completion of the second period; and
starting the next asynchronous replication cycle.

10 . The method of claim 7 wherein determining a time of a next asynchronous cycle switch comprises, if the asynchronous replication cycle transmission time is greater than the second period:
starting the next asynchronous replication cycle; and
continuing transmission of the asynchronous replication cycle.

11 . A system comprising:
a processor; and memory storing computer program code that when executed on the processor causes the processor to execute an asynchronous replication process operable to perform the operation sof:
performing asynchronous replication from a source to a target according to time-based replication cycles;
identifying a retention policy defining a number of asynchronous replication replicas to retain and a plurality of associated periods; and
retaining asynchronous replication replicas according to the policy.

12 . The system of claim 11 wherein computer program code operable to perform the operation of identifying a retention policy defining a number of asynchronous replication replicas to retain and a plurality of associated periods comprises computer program code operable to perform the operation of defining each successive period in the plurality of periods as a multiple of an immediately preceding period in the plurality of periods.

13 . The system of claim 12 wherein computer program code operable to perform the operation of retaining asynchronous replication replicas according to the policy comprises computer program code operable to perform the operation of retaining, for each successive period, a number of asynchronous replication replicas from the immediately preceding period in the plurality of periods.

14 . The system of claim 13 wherein a first period among the plurality of periods defines a minimal lag establishing a lower threshold of time between asynchronous replication cycles derived from a Recovery Point Objective defining a maximum amount of permitted data loss associated with recovery from the target.

15 . The system of claim 11 wherein computer program code operable to perform the operation of performing asynchronous replication from a source to a target according to time-based replication cycles comprises computer program code operable to perform the operation of, at a source side:
for each asynchronous replication cycle of a first level having a position in a series of replication cycles equal to a first multiple of a ratio of a first period and a second period, marking the asynchronous replication cycle of the first level as an asynchronous replication cycle of a second level; and
for each asynchronous replication cycle of the of the second level having a position in the series of replication cycles equal to a second multiple of a ratio of the second period and a third period, marking the asynchronous replication cycle of the second level as an asynchronous replication cycle of a third level.

16 . The system of claim 15 further comprising computer program code operable to perform the operation of, at a target side:
preserving each asynchronous replication cycle marked as the second level for the second period; and
preserving each asynchronous replication cycle marked as the third level for the third period.

17 . The system of claim 15 further comprising computer program code operable to perform the operation of, for asynchronous replication cycles having a transmission time exceeding the first period, determining a time of a next asynchronous replication cycle switch.

18 . The system of claim 17 wherein computer program code operable to perform the operation of determining a time of a next asynchronous cycle switch comprises computer program code operable to perform the operation of, if the asynchronous replication cycle transmission time is less than or equal to the difference between the second period and the first period, starting the next asynchronous replication cycle.

19 . The system of claim 17 wherein computer program code operable to perform the operation of determining a time of a next asynchronous cycle switch comprises computer program code operable to perform the operation of, if the asynchronous replication cycle transmission time is greater than the difference between the second period and the first period less than the second period:
waiting until completion of the second period; and
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Assignees

• Emc Corp

Inventors

• Meiri David
• Chen Xiangping

Classifications

• G06F11/1458 Primary

  Management of the backup or restore process · CPC title

• G06F11/1461

  Backup scheduling policy · CPC title

• G06F2201/84

  Using snapshots, i.e. a logical point-in-time copy of the data · CPC title

• G06F16/125

  characterised by the use of retention policies (retention policies for HSM systems G06F16/185) · CPC title

• G06F16/273 Primary

  Asynchronous replication or reconciliation · CPC title