# US 2013/0103649 A9 · Methods and apparatus for point-in-time volumes

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- Number: US 2013/0103649 A9
- Document ID: US20130103649A9
- Status: Published application
- Kind: A9
- Application number: 13/217,417
- Filed: 2011-08-25
- Published: 2013-04-25
- Earliest claimed: 2001-01-10
- Assignees: DataCore Software Corporation
- Inventors: David A. Linde
- Web page: https://patentgrep.com/patent/US20130103649A9

## CPC

- G06F 11/1469: {Backup restoration techniques}
- G06F 11/1466: {to make the backup process non-disruptive}
- G06F 12/121: using replacement algorithms
- G06F 2201/84: Using snapshots, i.e. a logical point-in-time copy of the data
- Y10S 707/99953: Recoverability
- Y10S 707/99955: Archiving or backup
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

Methods and apparatus for point-in-time volumes are provided. A relationship is enabled between a source volume and point-in-time volume. Copying a data chunk to the point-in-time volume before a write operation modifies the data chunk on the source volume dynamically creates the point-in-time volume. The point-in-time volume can be accessed in read/write mode as a general purpose data storage volume. Other embodiments comprising additional features, such as a forced migration process, are also provided.

## Claims

### Claim 1

A method for restoring a source volume to a past point in time from a point-in-time volume, the method comprising:
selecting one or more entries from a delta table that stores the one or more entries corresponding to original data chunks that have been stored on the point-in-time volume responsive to being modified on the source volume; and
transferring one or more original data chunks corresponding to the entries with a read operation directed to the point-in-time volume and a write operation directed to the source volume.

### Claim 2 (depends on 1)

The method of claim 1, further comprising clearing the selected one or more entries corresponding to the transferred one or more original data chunks.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
locking a plurality of data chunks; and
unlocking the selected one or more original data chunks in a decaying lock strategy.

### Claim 4 (depends on 1)

The method of claim 1, further comprising:
delaying transferring the one or more original data chunks responsive to a factor selected from the group consisting of: system utilization, system throughput, and system configuration.

### Claim 5 (depends on 1)

The method of claim 1, wherein a data chunk comprises a predetermined number of data blocks.

### Claim 6

A storage domain server for restoring a source volume to a past point in time from a point-in-time volume, comprising:
a delta table to select one or more entries, the delta table storing the one or more entries corresponding to original data chunks that have been stored on the point-in-time volume responsive to being modified on the source volume; and
an interface to transfer one or more original data chunks corresponding to the entries with a read operation directed to the point-in-time volume and a write operation directed to the source volume.

### Claim 7 (depends on 6)

The storage domain server of claim 6, wherein the delta table clears the selected one or more entries corresponding to the transferred one or more original data chunks.

### Claim 8

A computer program product, comprising:
a computer-readable medium having computer program logic embodied therein for a method of restoring a source volume to a past point in time from a point-in-time volume, the method comprising:
selecting one or more entries from a delta table that stores the one or more data chunks entries corresponding to original data chunks that have been stored on the point-in-time volume responsive to being modified on the source volume; and
transferring one or more original data chunks corresponding to the entries with a read operation directed to the point-in-time volume and a write operation directed to the source volume.

### Claim 9 (depends on 8)

The computer program product of claim 8, further comprising:
clearing the selected one or more entries corresponding to the transferred one or more original data chunks.

### Claim 10 (depends on 8)

The computer program product of claim 8, further comprising:
locking a plurality of data chunks; and
unlocking the selected one or more original data chunks in a decaying lock strategy.

### Claim 11

A method for changing a time reference for a point-in-time volume to a current time reference of a source volume, the method comprising:
selecting one or more entries from a delta table that stores the one or more entries corresponding to original data chunks that have been stored on the point-in-time volume responsive to being modified on the source volume; and
transferring one or more modified data chunks corresponding to the entries with a read operation directed to the source volume and a write operation directed to the point-in-time volume.

### Claim 12 (depends on 11)

The method of claim 11, further comprising clearing the selected one or more entries corresponding to the transferred one or more modified data chunks.

### Claim 13 (depends on 11)

The method of claim 11, further comprising:
locking a plurality of data chunks; and
unlocking the selected one or more modified data chunks in a decaying lock strategy.

### Claim 14 (depends on 11)

The method of claim 11, further comprising:
delaying transferring the one or more modified data chunks responsive to a factor selected from the group consisting of: system utilization, system throughput, and system configuration.

### Claim 15 (depends on 11)

The method of claim 11, wherein a data chunk comprises a predetermined number of data blocks.

### Claim 16

A storage domain server for changing a time reference for a point-in-time volume to a current time reference of a source volume, comprising:
a delta table to select one or more entries, the delta table storing the one or more entries corresponding to original data chunks that have been stored on the point-in-time volume responsive to being modified on the source volume; and
an interface to transfer one or more modified data chunks corresponding to the entries with a read operation directed to the source volume and a write operation directed to the point-in-time volume.

### Claim 17 (depends on 16)

The storage domain server of claim 16, wherein the delta table clears the selected one or more entries corresponding to the transferred one or more modified data chunks.

### Claim 18

A computer program product, comprising:
a computer-readable medium having computer program logic embodied therein for a method of changing a time reference for a point-in-time volume to a current time reference of a source volume, the method comprising:
selecting one or more entries from a delta table that stores the one or more entries corresponding to original data chunks that have been stored on the point-in-time volume responsive to being modified on the source volume; and
transferring one or more modified data chunks corresponding to the entries with a read operation directed to the source volume and a write operation directed to the point-in-time volume.

### Claim 19 (depends on 18)

The computer program product of claim 18, further comprising:
clearing the selected one or more entries corresponding to the transferred one or more modified data chunks.

### Claim 20 (depends on 18)

The computer program product of claim 18, further comprising:
locking a plurality of data chunks; and
unlocking the selected one or more modified data chunks in a decaying lock strategy.