Data storage planning

A non-transitory computer readable storage medium on which is stored machine readable instructions that when executed by a processor cause the processor to:

• create a formatting information area, create an index area for storing index data, and create a data area on one or more designated physical storage disks;
• allocate at least one data block to an upper-layer application in accordance with a size of a document needed to be stored;
• wherein formatting information in the formatting information area defines the index area and the data area, where the index area includes a sub-index area and at least one duplicate area of the sub-index area, where the data area includes a plurality of data blocks with a same size, and where the index area and the data area are stored on different physical storage disks;
• wherein the sub-index area comprises a volume index area, a plurality of sets of index areas, and a backup area of the volume index area;
• wherein the volume index area is located in a beginning location of the sub-index area, and the backup area of the volume index area is located in an ending location of the sub-index area;
• and
• wherein the index area comprises M number of sub-index areas, the backup area of the volume index area is located adjacent to a volume index area of an adjacent sub-index area, the backup area of the volume index area is activated when M is less than a predetermined threshold value N or when the volume index area of the adjacent sub-index area is damaged.