Backup and restoration for a deduplicated file system

A method of restoring data from a data storage system to a source file system that can store files in a deduplicated format, the method comprising:

• determining a block size value to restore a copied file in the deduplicated format;
• determining that a first data chunk of the copied file was not previously transmitted;
• in response to determining that the first data chunk of the copied file was not previously transmitted,
• transmitting the first data chunk to the source file system, and
• requesting updating a deduplication database at the source file system with a pointer to a location where the first data chunk is stored at;
• determining that a second data chunk of the copied file was previously transmitted;
• and
• in response to determining that the second data chunk of the copied file was previously transmitted,
• transmitting a request to the source file system to update the deduplication database at the source file system with a deduplication entry indicating that the second data chunk is duplicative, without transmitting the second data chunk to the source file system.

A computer program product comprising a computer-readable medium having instructions stored thereon, the instructions, when executed by a processor, causing the processor to implement a method of restoring data from a data storage system to a source file system that can store files in a deduplicated format, the method comprising:

• receiving a request for a file restoration operation,
• wherein the request for the file restoration operation comprises information about two or more files to restore,
• wherein the information about at least one file of the two or more files to restore includes information confirming a check that the at least one file of the two or more files to restore was stored in the deduplicated format locally on the source file system;
• determining that a first file of the two or more files is not to be restored in the deduplicated format;
• in response to determining that the first file of the two or more files is not to be restored in the deduplicated format, restoring the first file of the two or more files to a client computer of the source file system using a file input/output layer of the client computer;
• determining that a second file of the two or more files is to be restored in the deduplicated format;
• in response to determining that the second file of the two or more files is to be restored in the deduplicated format:
• determining a deduplication block size value to be used to restore the second file of the two or more files in the deduplicated format;
• for each data chunk in the second file of the two or more files, wherein each data chunk is of a size equal to the deduplication block size value:
• restoring respective data chunk on the client computer of the source file system;
• and
• transmitting a request to the client computer to update a local file system at the client computer to reflect the restoration of the respective data chunk.