Patent ID: 8914336

Claim:
A storage device comprising: a plurality of file systems included in a disk array device for storing data, the plurality of file systems each including a plurality of data, the plurality of data each having expiration date of storage period, a memory; and a processor to perform: storing all of the plurality of data stored in the plurality of file systems into the memory; setting the plurality of file systems to be restructured, relocating all of the plurality of data stored in the memory in ascending order of the expiration date of storage period of the data, selecting a file system from the plurality of file systems, calculating a free space in the selected file system, selecting one of the relocated plurality of data in ascending order of the expiration date of storage period of the data, determining whether a size of the selected one of the relocated plurality of data is less than or equal to a size of the calculated free space of the selected file system, storing the selected one of the relocated plurality of data in ascending order of the expiration date of storage period of the data into the selected file system, when determining that the size of the selected one of the relocated plurality of data is less than or equal to the size of the calculated free space of the selected file system, determining whether there is another one of the relocated plurality of data, which is not stored in the selected file system, having a size that is less than or equal to the size of the calculated free space of the selected file system, when determining that the size of the selected one of the relocated plurality of data is more than the size of the calculated free space of the selected file system, the another one of the relocated plurality of data having a largest size among the relocated plurality of data to be stored in the calculated free space of the selected file system, storing the another one of the relocated plurality of data into the selected file systems, when determining that there is the another one of the relocated plurality of data having a size that is less than or equal to a size of the calculated free space of the selected file system, selecting another file system from the plurality of file systems when determining that there is not the another one of the relocated plurality of data having a size that is less than or equal to a size of the calculated free space of the selected file system, and storing the selected one of the relocated plurality of data into the another file system in ascending order of the expiration date of storage period of the data.