# US 2014/0019696 A1 · Methods and apparatus for point-in-time volumes

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- Number: US 2014/0019696 A1
- Document ID: US20140019696A1
- Status: Published application
- Kind: A1
- Application number: 13/827,106
- Filed: 2013-03-14
- Published: 2014-01-16
- Earliest claimed: 2001-01-14
- Assignees: DataCore Software Corporation
- Inventors: David A. Linde
- Web page: https://patentgrep.com/patent/US20140019696A1

## 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 at position 1

1-20. (canceled)

### Claim 21

A method for creating point-in-time volumes, the method comprising:
creating a first point-in-time volume from a first source volume, the first point-in-time volume being configured for independent use as a second source volume without requiring reference to the first source volume; and
creating a second point-in-time volume based upon the first point-in-time volume.

### Claim 22 (depends on 21)

The method of claim 21, further comprising:
enabling a relationship between the second source volume and the second point-in-time volume;
receiving a data write operation directed to the second source volume;
determining whether the data write operation is directed to an original data block in the second source volume, the original data block being a data block existing in the source volume at the time the relationship is enabled;
reading the original data block from the second source volume prior to completing the data write operation where it is determined that the data write operation is directed to the original data block; and
storing the original data block in association with the second point-in-time volume.

### Claim 23

A non-transitory computer readable medium storing program code for creating point-in-time volumes, the program code being executable to perform operations comprising:
creating a first point-in-time volume from a first source volume, the first point-in-time volume being configured for independent use as a second source volume without requiring reference to the first source volume; and
creating a second point-in-time volume based upon the first point-in-time volume.

### Claim 24 (depends on 23)

The computer readable medium of claim 23, wherein the operations further comprise:
enabling a relationship between the second source volume and the second point-in-time volume;
receiving a data write operation directed to the second source volume;
determining whether the data write operation is directed to an original data block in the second source volume, the original data block being a data block existing in the source volume at the time the relationship is enabled;
reading the original data block from the second source volume prior to completing the data write operation where it is determined that the data write operation is directed to the original data block; and
storing the original data block in association with the second point-in-time volume.

### Claim 25

An apparatus for creating point-in-time volumes, the apparatus comprising:
a processor, and
a memory, the memory storing program code executable by the processor to perform operations comprising:
creating a first point-in-time volume from a first source volume, the first point-in-time volume being configured for independent use as a second source volume without requiring reference to the first source volume; and
creating a second point-in-time volume based upon the first point-in-time volume.

### Claim 26 (depends on 25)

The apparatus of claim 25, wherein the operations further comprise:
enabling a relationship between the second source volume and the second point-in-time volume;
receiving a data write operation directed to the second source volume;
determining whether the data write operation is directed to an original data block in the second source volume, the original data block being a data block existing in the source volume at the time the relationship is enabled;
reading the original data block from the second source volume prior to completing the data write operation where it is determined that the data write operation is directed to the original data block; and
storing the original data block in association with the second point-in-time volume.