Method and system for scan-free detection of auto-committed files in a write-once-read-many storage devices

Patent metadata

Field	Value
Publication number	US-10275465-B2
Application number	US-201715458506-A
Country	US
Kind code	B2
Filing date	Mar 14, 2017
Priority date	Mar 14, 2017
Publication date	Apr 30, 2019
Grant date	Apr 30, 2019

Abstract

A method and a system for detecting an occurrence of an auto-commit operation applied to files managed by a file server compliant with write-once-read-many (WORM) rules. The method includes: allocating a plurality of non-overlapping predefined time ranges starting from a newest-changed-files time range and ending at an oldest-changed-files time range, wherein the time ranges add up to an auto-commit period associated with the auto-commit operation; repeatedly updating a count of files whose file-change-time is associated respectively with one of the allocated time ranges, wherein the updating is carried out every time the predefined time range lapses; and detecting, every time the time range lapses, an occurrence of an auto-commit operation applied to at least one of the files stored on the volume within a duration of the time range since the updating, whenever the count of the files associated with the oldest-changed-files time range is non-zero.

First claim

The invention claimed is:

1. A system comprising:
a file system compliant with write-once-read-many (WORM) rules associated with an auto-commit operation applied to files managed by said file system and associated with respective volumes;
at least one data storage device configured to store said files of the at least one volume associated with the WORM rules; and
a set of counters, for each of the volumes, each of the counters associated with a non-overlapping time range starting from a newest-changed-files time range and ending at an oldest-changed-files time range, wherein the time ranger add up to an auto-commit period associated with the auto-commit operation, wherein the counters are stored on the at least one data storage device,
wherein the file system comprises, for each domain of files, a file system daemon configured to:
repeatedly update respective counts on the plurality of counters whose file-change-time is associated respectively with one of the allocated time range, wherein the update is carried out at whenever a duration of the time range lapses; and
determine, at an end of every time range, an occurrence of an auto-commit operation applied to at least one of the files stored on the volume, whenever the count of the files associated with the oldest-changed-files time range becomes non-zero.

2. The system according to claim 1 , wherein the WORM rules include a predefined retention period and an expiration date, wherein during the predefined retention period and up till the expiration date, the volume should not be deleted as long as the volume contains auto-committed files,
wherein responsive to the detecting of an occurrence of an auto-commit operation at a current time, the expiration date for the volume is updated whenever the predefined retention period plus the current time exceeds the expiration date previously defined for the volume.

3. The system according to claim 1 , wherein the file system daemon is configured to repeatedly update the counters by:
incrementing a count associated with the newest changed files time range, whenever a file is created in said volume;
decrementing a count associated with a time ranger that contains a file-change-time of a file that is deleted in said volume; and
incrementing a count associated with a time range that contains a file-change-time of a file that is modified and decrementing a count associated with the previous file time range.

4. The system according to claim 1 , wherein at an end of every time range lapsing, said file system is configured to update the count of each of the time ranges, with the count of its preceding time range and zero the count of the files associated with the newest-changed-files time range.

5. The system according to claim 2 , wherein responsive to increasing said predefined retention period into an updated retention period to the file system is configured to update said expiration date based on the updated retention period.

6. The system according to claim 1 , wherein responsive to changing said predefined auto-commit into an updated auto-commit period by said WORM policy engine, in a case that the updated auto-commit period is shorter than the predefined auto-commit period, the number of allocated time ranges is decreased by WORM policy engine, starting with the oldest-changed-files time range and newer time ranges, based on a ratio between the predefined auto-commit period and the updated auto-commit period, and
wherein the counters of the discarded time ranges are inspected, and the maximal expiration time is updated accordingly.

7. The system according to claim 1 , wherein responsive to changing said predefined auto-commit period into an updated auto-commit period, adding or subtracting counters so that the overall time ranges associated with the counters add up to the updated auto-commit period. the system according to claim 1 , wherein responsive to changing a length of said time range being said temporal resolution of the counter update into an updated time range, adding or subtracting counters so that the overall updated time ranges associated with the counters add up to the auto-commit period.

8. A method for determining an occurrence of an auto commit operation applied to files in a file system that is compliant with write-once-read-many (WORM) rules associated with said auto-commit operation associated with respective volumes stored on at least one data storage device;
allocating a set of counters, for each of said volumes, each of the counters associated with a non-overlapping time range starting from a newest-changed-files time range and ending at an oldest-changed-files time range, wherein said time ranges add up to an auto-commit period associated with said auto-commit operation, wherein said counters are stored on said at least one data storage device;
repeatedly updating respective counts on said plurality of counters whose file-change-time is associated respectively with one of said allocated time range, wherein the update is carried out every time a time range lapses; and
determining, at every time a time range lapses, an occurrence of an auto-commit operation applied to at least one of the files stored on said volume, whenever the count of the files associated with the oldest-changed-files time range becomes non-zero.

9. The method according to claim 8 , wherein the WORM rules include a predefined retention period and an expiration date, wherein during the predefined retention period and until the expiration date, said volume should not be deleted as long as said volume contains auto-committed files,
wherein responsive to said detecting of an occurrence of an auto-commit operation at a current time, said expiration date for said volume is updated whenever said predefined retention period plus said current time exceeds the expiration date previously defined for said volume.

10. The method according to claim 8 , wherein the repeatedly updating of said counters comprises:
incrementing a count associated with the newest changed files time range, whenever a file is created in said volume;
decrementing a count associated with a time range that contains a file-change-time of a file that is deleted in said volume; and
incrementing a count associated with a time range that contains a file-change-time of a file that is modified and decrementing a count associated with the file previous time range.

11. The method according to claim 8 , wherein at an end of every time range lapsing, updating the count of each of the time ranges, with the count of its preceding time range and zeroing the count of the files associated with the newest-changed-files time range.

12. The method according to claim 9 , wherein responsive to increasing said predefined retention period into an updated retention period, updating said expiration date based on the updated retention period.

13. The method according to claim 8 , wherein responsive to changing said predefined auto-commit period into an updated auto-commit period, adding or subtracting a number of the counters in the set of counters so that the overall time ranges associated with the counters add up to the updated auto-commit period.

14. The method according to claim 8 , wherein responsive to changing a length of said time range being said temporal resolution of the counter update, into an updated time range, adding or subtracting a number of the counters in the set of counters so that the overall updated time ranges associated with the counters add up to the auto-commit period.

15. A non-transitory computer readable medium for determining an occurrence of an auto commit ope

Assignees

• Dell Products Lp

Inventors

• Neria Noa
• Dar Itay
• Estrin Michael

Classifications

• G06F16/181

  providing write once read many [WORM] semantics · CPC title

• G06F16/1865

  Transactional file systems · CPC title

• G06F16/125 Primary

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

• G06F17/30188

  Physics · mapped topic

• G06F17/30085 Primary

  Physics · mapped topic