Incremental backup operations in a transactional file system
Various systems and methods for performing incremental backups in transactional file systems. For example, one method involves performing the first stage of a multi-stage write operation, where the write operation writes a data block. The method then involves performing a backup operation. However, the backup operation does not backup the modified block, since not all stages of the multi-stage write operation have been performed. The method involves updating metadata to indicate that though the data block was modified and a backup operation was performed, the data block was not included in the backup operation. After all stages of the multi-stage write operation have completed, e.g., a transaction is committed, a subsequent backup operation is performed. The data block is backed up during the subsequent backup operation.
1. A method comprising:
detecting a first stage of a write operation, wherein
the first stage of the write operation comprises changing data of a first data block;
in response to detecting the first stage of the write operation, updating changed blocked metadata to indicate that the first data block has been changed;
subsequent to the detecting, executing a first backup operation, wherein
the first backup operation occurs after the first stage of the write operation and before a second stage of the write operation,
the first data block is not included in the first backup operation,
non-protected block (NPB) metadata is set to indicate that the first data block has been changed but was not included in the first backup operation, and
the changed block metadata is cleared;
subsequent to completing the second stage of the write operation, updating file system metadata to indicate that the first data block has been committed; and
selecting the first data block to be included in a subsequent backup operation, wherein
the subsequent backup operation occurs after the second stage of the write operation, and
the selecting is based on the changed block metadata, the NPB metadata, and the file system metadata.
2. The method of claim 1 , further comprising:
updating the file system metadata in response to detecting the second stage of the write operation, wherein
the updating the file system metadata comprises including information identifying the first data block in the file system metadata.
3. The method of claim 1 , wherein
the selecting is based on detecting that information identifying the first data block is included in the NPB metadata and in the file system metadata.
4. The method of claim 3 , further comprising:
adding information identifying the first data block to changed block metadata in response to the detecting the first stage of the write operation.
5. The method of claim 1 , further comprising:
removing information identifying the first data block from the changed block metadata in response to the executing the first backup operation.
6. The method of claim 1 , wherein
the first backup operation comprises an incremental backup of a transactional file system.
7. The method of claim 1 , wherein
the selecting comprises comparing the NPB metadata with the changed block metadata and the file system metadata,
the NPB metadata identifies data blocks to be included in the subsequent backup operation, and
the file system metadata indicates which blocks in a storage device are in use.
8. The method of claim 1 , further comprising:
removing information identifying the first data block from the NPB metadata in response to executing the subsequent backup operation.
9. A non-transitory computer readable storage medium storing program instructions executable to:
detect a first stage of a write operation, wherein
the first stage of the write operation comprises changing data of a first data block;
in response to detecting the first stage of the write operation, update changed blocked metadata to indicate that the first data block has been changed;
subsequent to the detecting, execute a first backup operation, wherein
the first backup operation occurs after the first stage of the write operation and before a second stage of the write operation,
the first data block is not included in the first backup operation,
non-protected block (NPB) metadata is set to indicate that the first data block has been changed but was not included in the first backup operation, and
the changed block metadata is cleared;
subsequent to completing the second stage of the write operation, update file system metadata to indicate that the first data block has been committed; and
select the first data block to be included in a subsequent backup operation, wherein
the subsequent backup operation occurs after the second stage of the write operation, and
the selecting is based on the chanced block metadata, the NPB metadata, and the file system metadata.
10. The non-transitory computer readable storage medium of claim 9 , wherein the instructions are further executable to:
update the file system metadata in response to detecting the second stage of the write operation, wherein
updating the file system metadata comprises including information identifying the first data block in the file system metadata.
11. The non-transitory computer readable storage medium of claim 9 , wherein
selecting the first data block is based on detecting that information identifying the first data block is included in the NPB metadata and in the file system metadata.
12. The non-transitory computer readable storage medium of claim 9 , wherein the instructions are further executable to:
add information identifying the first data block to changed block metadata in response to detecting the first stage of the write operation.
13. The non-transitory computer readable storage medium of claim 9 , wherein the instructions are further executable to:
remove information identifying the first data block from the changed block metadata in response to executing the first backup operation.
14. The non-transitory computer readable storage medium of claim 9 , wherein
selecting the first data block comprises comparing the NPB metadata with the changed block metadata and the file system metadata,
the NPB metadata identifies data blocks to be included in the subsequent backup operation, and
the file system metadata indicates which blocks in a storage device are in use.
15. The non-transitory computer readable storage medium of claim 9 , wherein the instructions are further executable to:
remove information identifying the first data block from the NPB metadata in response to executing the subsequent backup operation.
16. A system comprising:
one or more processors; and
a memory coupled to the one or more processors, wherein the memory stores program instructions executable by the one or more processors to:
detect a first stage of a write operation, wherein
the first stage of the write operation comprises changing data of a first data block;
in response to detecting the first stage of the write operation, update changed blocked metadata to indicate that the first data block has been changed;
subsequent to the detecting, execute a first backup operation, wherein
the first backup operation occurs after the first stage of the write operation and before a second stage of the write operation,
the first data block is not included in the first backup operation,
non-protected block (NPB) metadata is set to indicate that the first data block has been changed but was not included in the first backup operation, and
the changed block metadata is cleared;
subsequent to completing the second stage of the write operation, update file system metadata to indicate that the first data block has been committed; and
select the first data block to be included in a subsequent backup operation, wherein
the subsequent backup operation occurs after the second stage of the write operation, and
selecting the first data block is based on the changed block metadata, the NPB metadata, and the file system metadata.
17. The system of claim 16 , wherein the instructions are further executable to:
update the file system metadata in response to detecting the second stage of the write operation, wherein
updating the file system metadata comprises including information identifying the first data block in the file system metadata.
18. The system of claim 16 , wherein
selecting the first data block is based on detecting that information identifying the first data block is included in the NPB metadata and in the file system metadata.
19. The system of claim 16 , wherein
selecting the first data block comprises comparing the NPB metadata with the changed block metadata and the file system metadata,
the NPB metadata identifies data blocks to be included in the subsequent backup operation, and
the file system metadata indicates which blocks in a storage device are in use.
20. The system of claim 16 , wherein the instructions are further executable to:
remove information identifying the first data block from changed block metadata in response to executing the first backup operation, and
remove information identifying the first data block from the NPB metadata in response to executing the subsequent backup operation.