IP Library › Granted Patent US 7,555,504
Granted Patent B2
US 7,555,504 · App. 10/668,546 · Granted Jun 30, 2009

Maintenance of a file version set including read-only and read-write snapshot copies of a production file

Assignee: EMC Corporation
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Quick Facts
Patent No.
US 7,555,504
App. No.
10/668,546
Filed
Sep 23, 2003
Granted
Jun 30, 2009
Kind
B2
Art Unit
2161
USPC
707/204
Abstract

Read-only and read-write snapshot copies of a production file in a Unix-based file system are organized as a version set of file inodes and shared file blocks. Version pointers and branch pointers link the inodes. Initially the production file can have all its blocks preallocated or it can be a sparse file having only an inode and its last data block. A protocol is provided for creating read-only and read-write snapshots, deleting snapshots, restoring the production file with a specified snapshot, refreshing a specified snapshot, and naming the snapshots. Block pointers are marked with a flag indicating whether or not the pointed-to block is owned by the parent inode. A non-owner marking is inherited by all of the block's descendants. The block ownership controls the copying of indirect blocks when writing to the production file, and also controls deallocation and passing of blocks when deleting a read-only snapshot.

Claims (33)

1. A file server comprising:

storage containing a file system; and

a processor coupled to the storage for accessing the file system;

wherein the file system includes a production file, read-only snapshot copies of the production file, and at least one read-write snapshot copy of the production file;

wherein the production file and the snapshot copies of the production file are organized as a version set; the version set including an inode for the production file and an inode for each snapshot copy of the production file, and a set of file blocks including data blocks and indirect blocks that are shared among the production file and the snapshot copies of the production file;

wherein the inodes in the version set include pointer fields, and wherein each pointer field includes a pointer to a block in the version set and a flag indicating whether or not the version of the production file of the inode is an oldest snapshot copy of the production file including an identical version of the block pointed to by the pointer in said each pointer field; and

wherein the file server is programmed to maintain for each block in each read-only snapshot copy of the production file an indication of whether or not said each snapshot copy of the production file is an oldest snapshot copy of the production file including an identical version of said each block by maintaining said flag indicating whether or not the version of the production file of the inode is an oldest snapshot copy of the production file including an identical version of the block pointed to by the pointer in said each pointer field.

2. The file server as claimed in claim 1 , wherein each inode of each read-only snapshot copy of the production file is linked to a hierarchy of blocks included in said each read-only snapshot copy of the production file, the inode of said each read-only snapshot copy of the production file includes an indication of whether or not said each read-only snapshot copy of the production file is an oldest read-only snapshot copy of the production file including an identical version of each block that is a child of said each inode in the hierarchy of blocks included in said each read-only snapshot copy of the production file, and when said each read-only snapshot copy of the production file is not an oldest read-only snapshot copy of the production file including an identical version of said each block that is a child of said each inode in the hierarchy the of blocks, then said each read-only snapshot copy of the production file is not an oldest read-only snapshot copy of the production file including an identical version of each descendant of said each block that is a child of said each inode in the hierarchy of the blocks.

3. The file server as claimed in claim 1 , which is programmed to delete a read-only snapshot copy of the production file, and when deleting the read-only snapshot copy of the production file, to keep each block for which the read-only snapshot copy is not indicated as being an oldest snapshot copy of the production file including an identical version of said each block.

4. The file server as claimed in claim 3 , wherein each inode of each read-only snapshot copy of the production file is linked to a hierarchy of blocks included in said each read-only snapshot copy of the production file, and wherein the file server is further programmed to keep all descendants of said each block for which the read-only snapshot copy is not indicated as being an oldest snapshot copy of the production file including an identical version of said each block.

5. The file server as claimed in claim 1 , which is programmed to delete a read-only snapshot copy of the production file, and when deleting the read-only snapshot copy of the production file, to keep each block for which the read-only snapshot copy of the production file is indicated as being an oldest snapshot copy of the production file including an identical version of said each block and a next-most recent version of the production file is indicated as not being an oldest snapshot copy of the production file including an identical version of said each block.

6. The file server as claimed in claim 5 , which is further programmed, upon deleting the read-only snapshot copy of the production file, to indicate that the next-most recent snapshot copy of the production file has become an oldest snapshot copy of the production file including an identical version of said each block for which the read-only snapshot copy of the production file is indicated as being an oldest snapshot copy of the production file including an identical version of said each block and a next-most recent snapshot copy of the production file is indicated as not being an oldest snapshot copy of the production file including an identical version of said each block.

7. The file server as claimed in claim 1 , which is programmed to delete a read-only snapshot copy of the production file by deallocating each block for which the read-only snapshot copy is indicated as an oldest read-only snapshot copy of the production file including an identical version of said each block and a next most recent read-only snapshot copy of the production file is also indicated as an oldest read-only snapshot copy of the production file including an identical version of a block corresponding to said each block, wherein said each block and the block corresponding to said each block are mapped to the same logical file addresses.

8. A file server comprising:

storage containing a file system; and

a processor coupled to the storage for accessing the file system;

wherein the file system includes a production file, and read-only snapshot copies of the production file;

wherein the production file and the read-only snapshot copies of the production file are organized as a version set; the version set including an inode for the production file, an inode for each read-only snapshot copy of the production file, and a set of file blocks including data blocks and indirect blocks that are shared among the production file and the read-only snapshot copies of the production file;

wherein the inodes in the version set include pointer fields, and wherein each pointer field includes a pointer to a block in the version set and a flag indicating whether or not the version of the production file of the inode is an oldest snapshot copy of the production file including an identical version of the block pointed to by the pointer in said each pointer field;

wherein the file server is programmed to maintain for each block in each snapshot copy of the production file an indication of whether or not said each snapshot copy of the production file is an oldest snapshot copy of the production file including an identical version of said each block by maintaining said flag indicating whether or not the version of the production file of the inode is an oldest snapshot copy of the production file including an identical version of the block pointed to by the pointer in said each pointer field; and

wherein the file server is programmed to delete a read-only snapshot copy of the production file, and when deleting the read-only snapshot copy of the production file, to keep each block for which the read-only snapshot copy is not indicated as being an oldest snapshot copy of the production file including an identical version of said each block.

9. The file server as claimed in claim 8 , wherein each inode of each read-only snapshot copy of the production file is linked to a hierarchy of blocks included in said each read-only snapshot copy of the production file, and wherein the file server is further programmed, upon deleting the read-only snapshot copy of the production file, to keep all descendants of said each block for which the read-only snapshot copy is not indicated as being an oldest snapshot copy of the production file including an identical version of said each block.

10. The file server as claimed in claim 8 , which is further programmed, upon deleting the read-only snapshot copy of the production file, to keep each block for which the read-only snapshot is indicated as being an oldest snapshot copy of the production file including an identical version of said each block and a next-most recent snapshot copy of the production file is indicated as not being an oldest snapshot copy of the production file including an identical version of said each block.

11. The file server as claimed in claim 10 , which is further programmed, upon deleting the read-only snapshot copy of the production file, to indicate that the next-most recent snapshot copy of the production file has become an oldest snapshot copy of the production file including an identical version of said each block for which the read-only snapshot is indicated as being an oldest snapshot copy of the production file including an identical version of said each block and a next-most recent snapshot copy of the production file is indicated as not being an oldest snapshot copy of the production file including an identical version of said each block.

12. The file server as claimed in claim 8 , which is further programmed, upon deleting the read-only snapshot copy of the production file, to deallocate each block for which the read-only snapshot copy is indicated as an oldest snapshot copy of the production file including an identical version of said each block and a next most recent snapshot copy of the production file is also indicated as an oldest snapshot copy of the production file including an identical version of a block corresponding to said each block, wherein said each block and the block corresponding to said each block are mapped to the same logical file addresses.

13. A method of operating a file server; the file server including storage containing a file system, and the file server also including a processor coupled to the storage for accessing the file system; the file system including a production file and read-only snapshot copies of the production file; the production file and the read-only snapshot copies of the production file being organized as a version set; the version set including an inode for the production file, an inode for each read-only snapshot copy of the production file, and a set of file blocks including data blocks and indirect blocks that are shared among the production file and the read-only snapshot copies of the production file, said method comprising:

maintaining for each block in each snapshot copy of the production file an indication of whether or not said each snapshot copy of the production file is an oldest snapshot copy of the production file including an identical version of said each block; and

deleting a read-only snapshot copy of the production file, wherein the deleting of the read-only snapshot copy of the production file includes keeping each block for which the read-only snapshot copy is not indicated as being an oldest snapshot copy of the production file including an identical version of said each block;

wherein the inodes in the version set include pointer fields, and each pointer field includes a pointer to a block in the version set and a flag indicating whether or not the version of the production file of the inode is an oldest snapshot copy of the production file including an identical version of the block pointed to by the pointer in said each pointer field, and wherein the step of maintaining for each block in each snapshot copy of the production file an indication of whether or not said each snapshot copy of the production file is an oldest snapshot copy of the production file including an identical version of said each block includes maintaining said flag to indicate whether or not the version of the production file of the inode is an oldest snapshot copy of the production file including an identical version of the block pointed to by the pointer in said each pointer field.

14. The method as claimed in claim 13 , wherein each inode of each read-only snapshot copy of the production file is linked to a hierarchy of blocks included in said each read-only snapshot copy of the production file, and wherein the deleting of the read-only snapshot copy of the production file includes keeping all descendants of said each block for which the read-only snapshot copy is not indicated as being an oldest snapshot copy of the production file including an identical version of said each block.

15. The method as claimed in claim 13 , wherein the deleting of the read-only snapshot copy of the production file further includes keeping each block for which the read-only snapshot copy of the production file is indicated as being an oldest snapshot copy of the production file including an identical version of said each block and a next-most recent snapshot copy of the production file is indicated as not being an oldest snapshot copy of the production file including an identical version of said each block.

16. The method as claimed in claim 15 , which further includes, upon deleting the read-only snapshot copy of the production file, indicating that the next-most recent snapshot copy of the production file has become an oldest snapshot copy of the production file including an identical version of said each block for which the read-only snapshot copy of the production file is indicated as being an oldest snapshot copy of the production file including an identical version of said each block and a next-most recent snapshot copy of the production file is indicated as not being an oldest snapshot copy of the production file including an identical version of said each block.

17. The method as claimed in claim 13 , wherein the deleting of the read-only snapshot copy of the production file includes deallocating each block for which the read-only snapshot copy of the production file is indicated as being an oldest snapshot copy of the production file including an identical version of said each block and a next most recent snapshot copy of the production file is also indicated as being an oldest snapshot copy of the production file including an identical version of a block corresponding to said each block, wherein said each block and the block corresponding to said each block are mapped to the same logical file addresses.

Assignments (11)
RELEASE OF SECURITY INTEREST IN PATENTS PREVIOUSLY RECORDED AT REEL/FRAME (053546/0001) Recorded Jun 23, 2022
From: THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A., AS NOTES COLLATERAL AGENT
To: DELL MARKETING L.P. (ON BEHALF OF ITSELF AND AS SUCCESSOR-IN-INTEREST TO CREDANT TECHNOLOGIES, INC.); DELL INTERNATIONAL L.L.C.; DELL PRODUCTS L.P.; DELL USA L.P.; EMC CORPORATION; DELL MARKETING CORPORATION (SUCCESSOR-IN-INTEREST TO FORCE10 NETWORKS, INC. AND WYSE TECHNOLOGY L.L.C.); EMC IP HOLDING COMPANY LLC
Reel/Frame 071642/0001 →
RELEASE OF SECURITY INTEREST IN PATENTS PREVIOUSLY RECORDED AT REEL/FRAME (045455/0001) Recorded May 20, 2022
From: THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A., AS NOTES COLLATERAL AGENT
To: DELL MARKETING CORPORATION (SUCCESSOR-IN-INTEREST TO ASAP SOFTWARE EXPRESS, INC.); DELL MARKETING L.P. (ON BEHALF OF ITSELF AND AS SUCCESSOR-IN-INTEREST TO CREDANT TECHNOLOGIES, INC.); DELL USA L.P.; DELL INTERNATIONAL L.L.C.; DELL PRODUCTS L.P.; DELL MARKETING CORPORATION (SUCCESSOR-IN-INTEREST TO FORCE10 NETWORKS, INC. AND WYSE TECHNOLOGY L.L.C.); EMC CORPORATION (ON BEHALF OF ITSELF AND AS SUCCESSOR-IN-INTEREST TO MAGINATICS LLC); EMC IP HOLDING COMPANY LLC (ON BEHALF OF ITSELF AND AS SUCCESSOR-IN-INTEREST TO MOZY, INC.); SCALEIO LLC
Reel/Frame 061753/0001 →
RELEASE OF SECURITY INTEREST IN PATENTS PREVIOUSLY RECORDED AT REEL/FRAME (040136/0001) Recorded Apr 26, 2022
From: THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A., AS NOTES COLLATERAL AGENT
To: DELL MARKETING CORPORATION (SUCCESSOR-IN-INTEREST TO ASAP SOFTWARE EXPRESS, INC.); DELL MARKETING L.P. (ON BEHALF OF ITSELF AND AS SUCCESSOR-IN-INTEREST TO CREDANT TECHNOLOGIES, INC.); DELL USA L.P.; DELL INTERNATIONAL L.L.C.; DELL PRODUCTS L.P.; DELL MARKETING CORPORATION (SUCCESSOR-IN-INTEREST TO FORCE10 NETWORKS, INC. AND WYSE TECHNOLOGY L.L.C.); EMC CORPORATION (ON BEHALF OF ITSELF AND AS SUCCESSOR-IN-INTEREST TO MAGINATICS LLC); EMC IP HOLDING COMPANY LLC (ON BEHALF OF ITSELF AND AS SUCCESSOR-IN-INTEREST TO MOZY, INC.); SCALEIO LLC
Reel/Frame 061324/0001 →
RELEASE OF SECURITY INTEREST Recorded Nov 3, 2021
From: CREDIT SUISSE AG, CAYMAN ISLANDS BRANCH
To: ASAP SOFTWARE EXPRESS, INC.; AVENTAIL LLC; CREDANT TECHNOLOGIES, INC.; DELL USA L.P.; DELL INTERNATIONAL, L.L.C.; DELL MARKETING L.P.; DELL PRODUCTS L.P.; DELL SOFTWARE INC.; DELL SYSTEMS CORPORATION; EMC CORPORATION; EMC IP HOLDING COMPANY LLC; FORCE10 NETWORKS, INC.; MAGINATICS LLC; MOZY, INC.; SCALEIO LLC; WYSE TECHNOLOGY L.L.C.
Reel/Frame 058216/0001 →
SECURITY AGREEMENT Recorded Apr 22, 2020
From: CREDANT TECHNOLOGIES INC.; DELL INTERNATIONAL L.L.C.; DELL MARKETING L.P.; DELL PRODUCTS L.P.; DELL USA L.P.; EMC CORPORATION; FORCE10 NETWORKS, INC.; WYSE TECHNOLOGY L.L.C.; EMC IP HOLDING COMPANY LLC
To: THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A.
Reel/Frame 053546/0001 →
SECURITY AGREEMENT Recorded Mar 21, 2019
From: CREDANT TECHNOLOGIES, INC.; DELL INTERNATIONAL L.L.C.; DELL MARKETING L.P.; DELL PRODUCTS L.P.; DELL USA L.P.; EMC CORPORATION; FORCE10 NETWORKS, INC.; WYSE TECHNOLOGY L.L.C.; EMC IP HOLDING COMPANY LLC
To: THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A.
Reel/Frame 049452/0223 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Sep 29, 2016
From: EMC CORPORATION
To: EMC IP HOLDING COMPANY LLC
Reel/Frame 040203/0001 →
SECURITY AGREEMENT Recorded Sep 21, 2016
From: ASAP SOFTWARE EXPRESS, INC.; AVENTAIL LLC; CREDANT TECHNOLOGIES, INC.; DELL USA L.P.; DELL INTERNATIONAL L.L.C.; DELL MARKETING L.P.; DELL PRODUCTS L.P.; DELL SOFTWARE INC.; DELL SYSTEMS CORPORATION; EMC CORPORATION; EMC IP HOLDING COMPANY LLC; FORCE10 NETWORKS, INC.; MAGINATICS LLC; MOZY, INC.; SCALEIO LLC; SPANNING CLOUD APPS LLC; WYSE TECHNOLOGY L.L.C.
To: THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A., AS NOTES COLLATERAL AGENT
Reel/Frame 040136/0001 →
SECURITY AGREEMENT Recorded Sep 21, 2016
From: ASAP SOFTWARE EXPRESS, INC.; AVENTAIL LLC; CREDANT TECHNOLOGIES, INC.; DELL USA L.P.; DELL INTERNATIONAL L.L.C.; DELL MARKETING L.P.; DELL PRODUCTS L.P.; DELL SOFTWARE INC.; DELL SYSTEMS CORPORATION; EMC CORPORATION; EMC IP HOLDING COMPANY LLC; FORCE10 NETWORKS, INC.; MAGINATICS LLC; MOZY, INC.; SCALEIO LLC; SPANNING CLOUD APPS LLC; WYSE TECHNOLOGY L.L.C.
To: CREDIT SUISSE AG, CAYMAN ISLANDS BRANCH, AS COLLATERAL AGENT
Reel/Frame 040134/0001 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Jan 13, 2004
From: ZHENG, JIANNAN; FAIBISH, SORIN
To: EMC CORPORATION
Reel/Frame 014880/0696 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Sep 23, 2003
From: BIXBY, PETER; MULLICK, SACHIN; JIANG, XIAOYE
To: EMC CORPORATION
Reel/Frame 014545/0931 →
Continuity (1)
Related Publication 20050065986A1 · Mar 24, 2005