Method, apparatus and computer program product for data backup

An apparatus for data backup, comprising:

• a processing unit;
• and
• memory coupled to the processing unit and storing instructions which, when executed by the processing unit, cause the apparatus to perform a method, the method comprising:
• obtaining first information that indicates changed data in a first block of a plurality of blocks of a local virtual disk, wherein the local virtual disk is an expandable virtual disk;
• determining, based on the first information, a block location of the first block in the local virtual disk;
• obtaining a first size of a backup virtual disk stored on a backup server;
• obtaining a second size of the local virtual disk subsequent to the data change, wherein the first size is smaller than the second size;
• and
• generating incremental backup data for the local virtual disk, wherein generating the incremental backup data comprises:
• determining, based on the first size, a first end location of the local virtual disk prior to the data change;
• determining, based on the second size, a second end location of the local virtual disk subsequent to the data change;
• generating, for a second block of the plurality of blocks, an indication to fill a corresponding second block of the backup virtual drive with a predetermined value, wherein the second block is located after the first end location;
• and
• generating the incremental backup data based on the block location, the first end location, and the second end location, wherein the incremental backup data comprises the indication and the changed data.

A non-transitory computer readable medium comprising instructions which, when executed by a processor, enables the processor to perform a method of data backup, the method comprising:

• obtaining first information that indicates changed data in a first block of a plurality of blocks of a local virtual disk, wherein the local virtual disk is an expandable virtual disk;
• determining, based on the first information, a block location of the first block in the local virtual disk;
• obtaining a first size of a backup virtual disk stored on a backup server;
• obtaining a second size of the local virtual disk subsequent to the data change, wherein the first size is smaller than the second size;
• and
• generating incremental backup data for the local virtual disk, wherein generating the incremental backup data comprises:
• determining, based on the first size, a first end location of the local virtual disk prior to the data change;
• determining, based on the second size, a second end location of the local virtual disk subsequent to the data change;
• generating, for a second block of the plurality of blocks, an indication to fill a corresponding second block of the backup virtual drive with a predetermined value, wherein the second block is located after the first end location;
• and
• generating the incremental backup data based on the block location, the first end location, and the second end location, wherein the incremental backup data comprises the indication and the changed data.