Fast snapshots

Patent metadata

Field	Value
Publication number	US-10013473-B2
Application number	US-201514848506-A
Country	US
Kind code	B2
Filing date	Sep 9, 2015
Priority date	Aug 30, 2011
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

A fast snapshot is configured to determine if a snapshot is utilized for asynchronous mirroring. The fast snapshot operation is performed by avoiding reference counts of the one or more data units associated with the snapshot from being updated at a creation time and a deletion time when the snapshot is utilized for asynchronous mirroring.

First claim

What is claimed is:

1. A method of performing a snapshot for monitoring usage of one or more data units by a processor device in a computing environment, the method comprising:
labeling a snapshot as a long-lived snapshot or a short-lived snapshot utilized for asynchronous mirroring; wherein the long-lived snapshot comprises a snapshot having reference counts which are updated at a creation time and a deletion time, and the short-lived snapshot comprises a regular reference-counted snapshot except having the reference counts which are not updated at the creation time and the deletion time, and further wherein the short-lived snapshots are used for the asynchronous mirroring having a recovery point objective (RPO) below a certain threshold;
avoiding the reference counts of the one or more data units associated with each short-lived snapshot from being updated at the creation time and the deletion time of each respective short-lived snapshot;
reference counting changes to the one or more data units associated with each long-lived snapshot each time the one or more data units are updated;
determining that a snapshot should be deleted;
determining whether the snapshot is a short-lived snapshot or a long-lived snapshot;
deleting the snapshot; and
when the snapshot is a short-lived snapshot, performing first reference count updates at a time other than the creation or the deletion time of each respective short-lived snapshot by performing:
decreasing the reference counts of the data units, when reference count background updates are actively updating, and
reverting the reference count background updates for decreasing the reference counts on each of the data units.

2. The method of claim 1 , further including, when the snapshot is determined to be short-lived, avoiding the reference counts from being updated.

3. The method of claim 2 , further including, subsequent to a change in at least one of those of the data units being written, performing at least one of:
maintaining a number of short-lived snapshots in the computing environment,
determining whether one of the data units is used by at least one of the short-lived snapshots, and
ignoring the reference counts of the short-lived snapshots, wherein one of the data units having a zero reference count is added to a data unit list.

4. The method of claim 1 , further including, when the snapshot is determined to be long-lived, updating the reference counts for each of the data units between the creation and the deletion time.

5. The method of claim 4 , further including, subsequent to a change in each of those of the data units being written, performing at least one of:
calculating a number of long-lived snapshots by checking for reference count background updates that are active, wherein the reference counts are updated by the reference count background updates, and
updating reference counts of data units for those of the reference count background updates yet to be performed.

6. The method of claim 1 , further including, upon a deletion of a snapshot determined to be short-lived, performing at least one of:
when a number of short-lived snapshots is maintained:
decreasing the reference counts only on the data units that were overwritten during an existence of the short-lived snapshots, and

when the reference counts of the short-lived snapshots are ignored:
checking each of the data units against a data model for verifying that each of the data units are referenced by the short-lived snapshots.

7. The method of claim 1 , further including, upon a deletion of a snapshot determined to be long-lived, performing at least one of:
decreasing the reference counts of the data units,
when reference count background updates are actively updating, reverting the reference count background updates for decreasing the reference counts on each of the data units, and
when the reference count background updates are not actively updating, starting the reference count background updates and decreasing the reference counts on each of the data units.

8. A system for performing a snapshot for monitoring usage of one or more data units in a computing environment, comprising:
a processor device operable in the computing environment;
a snapshot module in communication with the processor device, the snapshot module adapted for labeling a snapshot as a long-lived snapshot or a short-lived snapshot utilized for asynchronous mirroring; wherein the long-lived snapshot comprises a snapshot having reference counts which are updated at a creation time and a deletion time, and the short-lived snapshot comprises a regular reference-counted snapshot except having the reference counts which are not updated at the creation time and the deletion time and further wherein the short-lived snapshots are used for the asynchronous mirroring having a recovery point objective (RPO) below a certain threshold; and
a reference count module in communication with the snapshot module and the processor device, wherein the reference count module is adapted for avoiding the reference counts of the one or more data units associated with each short-lived snapshot from being updated at the creation time and flail the deletion time of each respective short-lived snapshot;
reference counting changes to the one or more data units associated with each long-lived snapshot each time the one or more data units are updated;
determining that a snapshot should be deleted;
determining whether the snapshot is a short-lived snapshot or a long-lived snapshot;
deleting the snapshot; and
when the snapshot is a short-lived snapshot, performing first reference count updates at a time other than the creation or the deletion time of each respective short-lived snapshot by performing:
decreasing the reference counts of the data units, when reference count background updates are actively updating, and
reverting the reference count background updates for decreasing the reference counts on each of the data units.

9. The system of claim 8 , wherein the reference count module is further adapted for, when the snapshot is determined to be short-lived, avoiding the reference counts from being updated.

10. The system of claim 9 , wherein the processor device is further adapted for, subsequent to a change in at least one of those of the data units being written, performing at least one of:
maintaining a number of short-lived snapshots in the computing environment,
determining whether one of the data units is used by at least one of the short-lived snapshots, and
ignoring the reference counts of the short-lived snapshots, wherein one of the data units having a zero reference count is added to a data unit list.

11. The system of claim 8 , wherein the reference count module is further adapted for, when the snapshot is determined to be long-lived, updating the reference counts for each of the data units between the creation and the deletion time.

12. The system of claim 11 , wherein the reference count module is further adapted for, subsequent to a change in each of those of the data units being written, performing at least one of:
calculating a number of long-lived snapshots by checking for reference count background updates that are active, wherein the reference counts are updated by the reference count background updates, and
updating reference counts of data units for those of the reference count background updates yet to be performed.

13. The system of claim 8 , wherein the reference count module is further adapted for, upon a deletion of a snapshot determined to be short-lived, performing at least one of:
when a number of short-lived snapshots is mai

Assignees

• IBM

Inventors

• Keller Michael
• Nissan-Messing Orit
• Shemesh Dani
• Weissbrem Eliyahu

Classifications

• G06F2201/84

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

• G06F2201/80

  Database-specific techniques · CPC title

• G06F17/30876

  Physics · mapped topic

• G06F17/30578 Primary

  Physics · mapped topic

• G06F12/16

  Protection against loss of memory contents {(contains no material, see G06F11/00)} · CPC title