US 8,135,678 B1Granted

System and method for restoring a single data stream file from a snapshot

AssigneeNetApp, Inc.

InventorsRaymond C. Chen, Kayuri Patel, Vijayan Rajan

Life of this patent

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Abstract

A file which has been changed from a data storage system is restored. If the file was changed from an active file system, a set of twin pointers is created by copying from the latest pointers in the active file system before the file system was changed. A pointer from the twin pointers is compared with a pointer from a snapshot of the active file system. If a pointer from the twin pointers points to a same data block as the pointer from the snapshot, the twin pointer is written into the active file system to restore the file to the active file system. If the pointers do not point to the same data block, a data of the block is copied to a new block in the active file system to restore data changed since the snapshot was taken.

Claims11

Dependent claims

A method for restoring data from a snapshot, comprising:

maintaining an active file system by a storage system;
writing a snapshot of the active file system at a first state to persistent storage;
modifying a data object of the active file system at a second state;
receiving a command at a third state to restore the data object to the first state;
creating a twin inode by copying an inode of the active file system which points to the data object at the third state;
comparing a pointer in the snapshot with a pointer in the twin inode;
and
in response to the pointer in the twin matching the pointer in the snapshot, writing the pointer in the twin into the restored active file system, wherein the pointer in the restored active file system points to a block in use at the first state and in response to the pointer in the twin not matching the pointer in the snapshot, writing the pointer from the snapshot into the restored active file system to restore the restored active file system to the first state, and writing the block pointed to by the pointer in the snapshot into the restored active file system to restore the restored active file system to the first state;
and in response to the pointer in the twin not matching the pointer in the snapshot, determining if the block pointed to by the twin pointer is allocated in the active file system;
and copying, if the block is allocated in the active file system, a data of the block to a new block in the active file system;
and copying, if the block is not allocated in the active file system, the pointer of the snapshot to the new pointer .

8 more elements

A data storage system, comprising:

a processor configured to execute a storage operating system, the storage operating system, when executed, configured to,
write a snapshot of a first state to persistent storage;
modify a data object of the storage operating system at a second state;
receive a command at a third state to restore the data object to the first state;
create a twin inode by copying an inode of the storage operating system which points to the data object at the third state;
compare a pointer in the snapshot with a pointer in the twin inode;
and
write, in response to the pointer in the twin matching the pointer in the snapshot, the pointer in the twin into a restored system, wherein the pointer in the restored system points to a block in use at the first state and wherein the storage operating system, when executed, is further configured to write, in response to the pointer in the twin not matching the pointer in the snapshot, the pointer from the snapshot into the restored system to restore the data object to the first state, and further configured to write the block pointed to by the pointer in the snapshot into the restored system at the first state;
and wherein the storage operating system, when executed, is further configured to:
determine, in response to the pointer in the twin not matching the pointer in the snapshot, if the block pointed to by the twin pointer is allocated in the storage operating system;
and copy, if the block is allocated in the storage operating system, a data of the block to a new block in the storage operating system;
and wherein the storage operating system, when executed, is further configured to copy, if the block is not allocated in the storage operating system, the pointer of the snapshot to the new pointer.

9 more elements

A computer-readable storage medium stored with executable program instructions for execution by a processor, the computer-readable storage medium comprising:

program instructions that write a snapshot of a first state to persistent storage;
program instructions that modify a data object of a storage operating system at a second state;
program instructions that receive a command at a third state to restore the data object to the first state;
program instructions that create a twin inode by copying an inode of the storage operating system which points to the data object at the third state;
program instructions that compare a pointer in the snapshot with a pointer in the twin inode;
and
program instructions that write, in response to the pointer in the twin matching the pointer in the snapshot, the pointer in the twin into a restored system, wherein the pointer in the restored system points to a block in use at the first state and program instructions that:
write, in response to the pointer in the twin not matching the pointer in the snapshot, the pointer from the snapshot into the restored system to restore the data object to the first state, and write the block pointed to by the pointer in the snapshot into the restored system at the first state;
and program instructions that:
determine, in response to the pointer in the twin not matching the pointer in the snapshot, if the block pointed to by the twin pointer is allocated in the storage operating system;
and copy, if the block is allocated in the storage operating system, a data of the block to a new block in the storage operating system;
and program instructions that copy, if the block is not allocated in the storage operating system, the pointer of the snapshot to the new pointer.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/213,628Filed 19 Aug 2011 · continuation
Priority: 25 Jun 2001
Granted: 13 Mar 2012
Term ends: Not estimatedThe source records don’t support an estimate.

Classification10 codes

G06F 16/10
Information retrieval; Database structures therefor; File system structures therefor: file systems; File servers
G06F 3/0622
Securing storage systems: in relation to access
G06F 3/0643
Organizing or formatting or addressing of data: management of files
G06F 3/067
Adopting a particular infrastructure: distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Family

Application09/891,159Parent of this continuation-in-part · filed 25 Jun 2001
Application10/393,781Parent of this continuation · filed 21 Mar 2003
US 6,643,654 B1Parent of this continuation-in-part · filed 4 Nov 2003
Application11/650,768Parent of this continuation · filed 8 Jan 2007
US 7,165,079 B1Parent of this continuation · filed 16 Jan 2007
US 8,010,503 B1Parent of this continuation
Application10/393,781Parent of this continuation-in-part
US 8,135,678 B1This patent

From the US filing history. Foreign family members aren’t listed.