Identifying changed files in incremental block-based backups to backup indexes
Embodiments are directed to a method of identifying changed files in incremental block based backups, by obtaining changed data blocks of a file from a change block tracking (CBT) driver, wherein the file has an associated master file table (MFT) record and a parent MFT record number used in a file system, and constructing a complete file path of the file by traversing from the changed MFT record to the root directory using respective parent MFT record numbers by iteratively parsing each record by extracting the file name and parent MFT record number and appending the file name to a previous MFT record file name.
1. A computer-implemented method of identifying changed files in incremental block based backups, comprising:
obtaining changed data blocks of a file from a change block tracking (CBT) driver, wherein the file has an associated master file table (MFT) record and a parent MFT record number used in a file system;
constructing a complete file path of the file by traversing from the changed MFT record to the root directory using respective parent MFT record numbers by iteratively parsing each record by extracting the file name and parent MFT record number and appending the file name to a previous MFT record file name to create an appended file name;
indexing only the changed data blocks of the complete file path using the extracted MFT file name and parent MFT record number to create a set of indexes for backup; and
providing the appended file name and the indexes to a backup engine to backup data blocks comprising the file, wherein the backed up indexes eliminate a need to traverse and mount a data saveset including the file to allow a user to perform a specific search operation.
2. The method of claim 1 wherein the system comprises a Microsoft Windows based network, and wherein the file system is NTFS.
3. The method of claim 2 wherein the master file table (MFT) comprises records that represent corresponding files and folders in the NTFS system, and wherein an MFT zone location is stored in NTFS boot information.
4. The method of claim 3 further comprising:
parsing an NTFS boot record to obtain MFT zone location information for data blocks of the file; and
intersecting MFT zone blocks obtained in the parsing step with the changed data blocks.
5. The method of claim 4 wherein the intersecting step comprises scanning and comparing a block location of the file table zone and received block identifiers to find matching blocks.
6. The method of claim 5 further comprising comparing a modification time for the each record to eliminate MFT records with corresponding access times that are also part of changed blocks.
7. The method of claim 1 wherein the appended file name corresponds to a full file system path of the file as defined by the file system.
8. The method of claim 1 wherein the block based backups executed on client machines that are part of a data domain backup system.
9. A system comprising a processor-based executable module configured to identify changed files in incremental block based backups in a large-scale data storage system, comprising:
a reverse mapping component mapping each changed data block to a file to which the block belongs by obtaining changed data blocks of a file from a change block tracking (CBT) driver, wherein the file has an associated master file table (MFT) record and a parent MFT record number used in a file system; and
a recursive processing component constructing a complete file path of the file by traversing from the changed MFT record to the root directory using respective parent MFT record numbers by iteratively parsing each record by extracting the file name and parent MFT record number and appending the file name to a previous MFT record file name to create an appended file name, indexing only the changed data blocks of the complete file path using the extracted MFT file name and parent MFT record number to create a set of indexes for backup, and providing the appended file name and the indexes to a backup engine to backup data blocks comprising the file, wherein the backed up indexes eliminate a need to traverse and mount a data saveset including the file to allow a user to perform a specific search operation.
10. The system of claim 9 wherein the system comprises a Microsoft Windows based network, and wherein the file system is NTFS, and wherein the master file table (MFT) comprises records that represent corresponding files and folders in the NTFS system, and wherein an MFT zone location is stored in NTFS boot information.
11. The system of claim 10 further comprising:
a parser parsing an NTFS boot record to obtain MFT zone location information for data blocks of the file; and
an intersecting component intersecting MFT zone blocks obtained in the parsing step with the changed data blocks.
12. The system of claim 11 wherein the intersecting component scans and compares a block location of the file table zone and received block identifiers to find matching blocks.
13. The system of claim 12 further comprising a comparator comparing a modification time for the each record to eliminate MFT records with corresponding access times that are also part of changed blocks.
14. The system of claim 9 wherein the appended file name corresponds to a full file system path of the file as defined by the file system.
15. The system of claim 9 wherein the block based backups executed on client machines that are part of a data domain backup system.
16. A computer program product, comprising a non-transitory computer-readable medium having a computer-readable program code embodied therein, the computer-readable program code adapted to be executed by one or more processors to implement a method for identifying changed files in incremental block based backups, by:
obtaining changed data blocks of a file from a change block tracking (CBT) driver, wherein the file has an associated master file table (MFT) record and a parent MFT record number used in a file system; and
constructing a complete file path of the file by traversing from the changed MFT record to the root directory using respective parent MFT record numbers by iteratively parsing each record by extracting the file name and parent MFT record number and appending the file name to a previous MFT record file name to create an appended file name;
indexing only the changed data blocks of the complete file path using the extracted MFT file name and parent MFT record number to create a set of indexes for backup; and
providing the appended file name and the indexes to a backup engine to backup data blocks comprising the file, wherein the backed up indexes eliminate a need to traverse and mount a data saveset including the file to allow a user to perform a specific search operation.
17. The computer program product of claim 16 wherein the system comprises a Microsoft Windows based network, and wherein the file system is NTFS, and wherein the master file table (MFT) comprises records that represent corresponding files and folders in the NTFS system, and wherein an MFT zone location is stored in NTFS boot information.
18. The computer program product of 17 , wherein the method further comprises:
parsing an NTFS boot record to obtain MFT zone location information for data blocks of the file; and
intersecting MFT zone blocks obtained in the parsing step with the changed data blocks, wherein the intersecting step comprises scanning and comparing a block location of the file table zone and received block identifiers to find matching blocks.
19. The computer program product of claim 18 wherein the method further comprises comparing a modification time for the each record to eliminate MFT records with corresponding access times that are also part of changed blocks.
20. The computer program product of claim 19 wherein the appended file name corresponds to a full file system path of the file as defined by the file system.