Managing truncation of files of file systems

Patent metadata

Field	Value
Publication number	US-10242012-B1
Application number	US-201514870556-A
Country	US
Kind code	B1
Filing date	Sep 30, 2015
Priority date	Sep 30, 2015
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

A method is used in managing truncation of files of file systems. A request is received to delete a portion of a file of a file system. A set of extents associated with the portion of the file is determined where the file has been identified for deletion. A replica of the set of extents is created. The replica represents a state of the set of extents at a particular prior point in time. The portion of the file is deleted by updating metadata of the file. The replica is asynchronously deleted in background.

First claim

What is claimed is:

1. A method for use in managing truncation of files of file systems, the method comprising
receiving a request to delete a portion of a file of a file system, wherein a file system mapping component manages the file system, wherein the file system includes a set of files, each file associated with extents, each file associated with an inode, wherein the inode of a file includes metadata of the file, wherein the file system is associated with a set of sparse volumes, wherein a sparse volume includes a set of slices, each slice of the set of slices is a logical representation of a subset of physical disk storage;
determining a set of extents associated with the portion of the file identified for deletion;
creating a replica of the set of extents, wherein the replica represents a state of the set of extents at a particular prior point in time;
deleting the portion of the file by updating metadata of the file to indicate that the portion of the file no longer references to the replica thereby enabling the deletion of the portion of the file without having to deallocate each extent associated with the portion of the file; and
asynchronously deleting the replica in background.

2. The method of claim 1 , wherein the replica is an internal snapshot of the file, wherein the internal snapshot is not accessible to a user of the file.

3. The method of claim 1 , wherein the replica includes holes at locations within a logical address space of the replica, wherein the locations indicates file systems blocks of the file that are not included in the set of extents.

4. The method of claim 1 , wherein the portion of the file is deleted based on a delegated reference counting mechanism.

5. The method of claim 1 , wherein the file is truncated in size by deleting the portion of the file.

6. The method of claim 1 , wherein the portion of the file selected for deletion is associated with a set of indirect data blocks, each indirect data block of the set of indirect blocks pointing to a set of data blocks.

7. The method of claim 1 , wherein the file includes a set of file system blocks, wherein a mapping pointer is associated with a file system block, wherein the mapping pointer includes a distributed weight indicating whether the file system block has been shared.

8. The method of claim 1 , wherein updating the metadata of the file includes adding weight of each file system block shared between the replica and the file to a mapping pointer associated with each shared file system block.

9. The method of claim 1 , wherein the file system resides on a storage system, wherein the storage system includes a disk drive system comprising a plurality of Redundant Array of Inexpensive Disks (RAID) systems, each RAID system of the plurality of RAID systems having a first disk drive and a second disk drive.

10. A system for use in managing truncation of files of file systems, the system comprising a processor configured to:
receive a request to delete a portion of a file of a file system, wherein a file system mapping component manages the file system, wherein the file system includes a set of files, each file associated with extents, each file associated with an inode, wherein the inode of a file includes metadata of the file, wherein the file system is associated with a set of sparse volumes, wherein a sparse volume includes a set of slices, each slice of the set of slices is a logical representation of a subset of physical disk storage;
determine a set of extents associated with the portion of the file identified for deletion;
create a replica of the set of extents, wherein the replica represents a state of the set of extents at a particular prior point in time;
delete the portion of the file by updating metadata of the file to indicate that the portion of the file no longer references to the replica thereby enabling the deletion of the portion of the file without having to deallocate each extent associated with the portion of the file; and
asynchronously delete the replica in background.

11. The system of claim 10 , wherein the replica is an internal snapshot of the file, wherein the internal snapshot is not accessible to a user of the file.

12. The system of claim 10 , wherein the replica includes holes at locations within a logical address space of the replica, wherein the locations indicates file systems blocks of the file that are not included in the set of extents.

13. The system of claim 10 , wherein the portion of the file is deleted based on a delegated reference counting mechanism.

14. The system of claim 10 , wherein the file is truncated in size by deleting the portion of the file.

15. The system of claim 10 , wherein the portion of the file selected for deletion is associated with a set of indirect data blocks, each indirect data block of the set of indirect blocks pointing to a set of data blocks.

16. The system of claim 10 , wherein the file includes a set of file system blocks, wherein a mapping pointer is associated with a file system block, wherein the mapping pointer includes a distributed weight indicating whether the file system block has been shared.

17. The system of claim 10 , wherein updating the metadata of the file includes adding weight of each file system block shared between the replica and the file to a mapping pointer associated with each shared file system block.

18. The system of claim 10 , wherein the file system resides on a storage system, wherein the storage system includes a disk drive system comprising a plurality of Redundant Array of Inexpensive Disks (RAID) systems, each RAID system of the plurality of RAID systems having a first disk drive and a second disk drive.

Assignees

• Emc Corp
• Emc Ip Holding Co Llc

Inventors

• Basov Ivan
• Armangau Philippe
• Davenport William C

Classifications

• G06F3/0689

  Disk arrays, e.g. RAID, JBOD · CPC title

• G06F16/184

  implemented as replicated file system · CPC title

• G06F16/18

  File system types · CPC title

• G06F3/0643

  Management of files · CPC title

• G06F16/128 Primary

  Details of file system snapshots on the file-level, e.g. snapshot creation, administration, deletion (error detection or correction of the data by redundancy in operations or in hardware G06F11/14, G06F11/16) · CPC title