Change tracking between snapshots of a source storage
Change tracking between snapshots of a source storage. In one example embodiment, a method includes various steps. For example, the method includes, at time t(1), starting tracking, in a change log, locations in a source storage of all blocks that are changed after time t(1). The method also includes, between time t(1) and time t(3), changing a block in the source storage. The method further includes, at time t(3), creating a first snapshot of the source storage. The method also includes, after time t(3), creating a first image backup using the first snapshot. The method further includes, at time t(8), creating a second snapshot of the source storage. The method also includes, at time t(11), creating an incremental image backup that includes all blocks in the second snapshot that are tracked as having been changed in the change log after time t(1).
1. A method of tracking changes between snapshots of a source storage, the method comprising:
at time t(1), starting tracking, in a change log, locations in a source storage of all blocks that are changed after time t(1);
between time t(1) and time t(3), changing a block in the source storage by a file system executing a write command;
at time t(3), starting a first snapshot operation on the source storage, the first snapshot operation including creating a first snapshot of the source storage by, for each write command including a target location received by the file system after time t(3), copying a block at the target location for safekeeping prior to changing the block at the target location by the file system executing the write command;
after time t(3), creating a first image backup using the first snapshot;
at time t(8), starting a second snapshot operation on the source storage, the second snapshot operation including creating a second snapshot of the source storage by, for each write command including a target location received by the file system after time t(8), copying a block at the target location for safekeeping prior to changing the block at the target location by the file system executing the write command; and
at time t(11), creating an incremental image backup that includes all blocks in the second snapshot that are tracked as having been changed in the change log after time t(1).
2. The method as recited in claim 1 , wherein the first image backup is a full image backup.
3. The method as recited in claim 1 , wherein the first image backup is an incremental image backup.
4. The method as recited in claim 1 , further comprising:
at time t(5), finishing the first snapshot operation and discarding the first snapshot.
5. The method as recited in claim 1 , further comprising:
at time t(6), starting tracking, in a change log, locations in a source storage of all blocks that are changed after time t(6).
6. The method as recited in claim 1 , further comprising:
between time t(6) and time t(8), changing a block in the source storage by the file system executing a write command.
7. The method as recited in claim 1 , further comprising:
between time t(8) and time t(10), changing a block in the source storage by the file system executing a write command.
8. The method as recited in claim 7 , further comprising:
at time t(10), finishing tracking, in the change log, locations in the source storage of all blocks that are changed after time t(1).
9. The method as recited in claim 8 , further comprising:
at time t(12), finishing the second snapshot operation and discarding the second snapshot.
10. A non-transitory computer-readable medium storing a program that causes a processor to execute the method as recited in claim 1 .
11. A method of tracking changes between snapshots of a source storage, the method comprising:
at time t(1), starting tracking, in a change log, locations in a source storage of all blocks that are changed after time t(1);
at time t(3), starting a first snapshot operation on the source storage, the first snapshot operation including creating a first snapshot of the source storage by, for each write command including a target location received by the file system after time t(3), copying a block at the target location for safekeeping prior to changing the block at the target location by the file system executing the write command;
after time t(3), creating a first image backup using the first snapshot;
at time t(8), starting a second snapshot operation on the source storage, the second snapshot operation including creating a second snapshot of the source storage by, for each write command including a target location received by the file system after time t(8), copying a block at the target location for safekeeping prior to changing the block at the target location by the file system executing the write command;
between time t(8) and time t(11), changing a block in the source storage by a file system executing a write command; and
at time t(11), creating an incremental image backup that includes all blocks in the second snapshot that are tracked having been changed in the change log after time t(1).
12. The method as recited in claim 11 , wherein the first image backup is a full image backup.
13. The method as recited in claim 11 , wherein the first image backup is an incremental image backup.
14. The method as recited in claim 11 , further comprising:
at time t(5), finishing the first snapshot operation and discarding the first snapshot.
15. The method as recited in claim 11 , further comprising:
at time t(6), starting tracking, in a change log, locations in a source storage of all blocks that are changed after time t(6).
16. The method as recited in claim 11 , further comprising:
between time t(1) and time t(3), changing a block in the source storage by the file system executing a write command.
17. The method as recited in claim 11 , further comprising:
between time t(6) and time t(8), changing a block in the source storage by a file system executing a write command.
18. The method as recited in claim 17 , further comprising:
at time t(10), finishing tracking, in the change log, locations in the source storage of all blocks that are changed after time t(1).
19. The method as recited in claim 18 , further comprising:
at time t(12), finishing the second snapshot operation and discarding the second snapshot.
20. A non-transitory computer-readable medium storing a program that causes a processor to execute the method as recited in claim 11 .