Data backup using metadata mapping
An information processing apparatus, backup method, and program product that enable efficient differential backup. In one embodiment, an information processing apparatus for files stored in a storage device includes: a metadata management unit for managing metadata of files stored in the storage device; a map generation unit for generating a map which indicates whether metadata associated with an identification value uniquely identifying a file in the storage device is present or absent; and a backup management unit for scanning the metadata to detect files that have been created, modified, or deleted since the last backup, and storing at least a data block and the metadata for a detected file in a backup storage device as backup information in association with the identification value.
1. A method for an information processing apparatus to back up files stored in a storage device by the information processing apparatus loading a program into memory and executing the program, comprising the operations of:
generating or deleting metadata of a file stored in the storage device;
generating a map which indicates whether the metadata associated with an identification value uniquely identifying a file in the storage device is present or absent;
scanning the metadata on each run of a backup process to detect files that have been created, modified, or deleted since a last backup, and storing the map for current files, at least a data block, and the metadata for a detected file in a backup storage device as backup information in association with the identification value;
wherein generating or deleting metadata of a file comprises, for respective files, generating a respective file size, a respective last update time, a respective identification value, and a respective data block address;
wherein the map for current files comprises an inode bitmap, wherein the data block comprises differential data for the detected file, and wherein the metadata for the detected file comprises inode information for the detected file; wherein the method further comprises:
restoring data by restoring at least the inode information for the detected file and the differential data for the detected file based on the inode bitmap having a bit set to 1 for the detected file.
2. The method according to claim 1 , wherein the map is a bitmap in which the presence or absence of the metadata is represented by a binary value.
3. The method according to claim 1 , wherein the operation of storing in the backup storage device comprises storing in a remote storage over a network.
4. The method according to claim 1 , wherein the operation of storing in the backup storage device comprises storing in a local storage via a storage adapter.