Patent ID: 7464222
Filing Date: 2008-12-09
Classification: G06F

Abstract:
1. A first storage system connected to a management terminal, a computer, and a second storage system, comprising: a memory; a first storage device which stores data related to a first file system; a first controller which provides the first file system and a second file system to a computer; and a second controller for controlling input/output operations to/from the second storage system with location of data related to the second file system, wherein the second storage system includes a second storage device which stores the data related to the second file system and a third controller, connected to the second controller, for controlling the second storage device, wherein the first controller mounts a root directory of the second file system at a mount point of the first file system in the first storage system such that the first and second file systems are provided to the computer as a single directory tree, wherein the second controller accesses the second storage system with a command representing an area where the data related to the second file system is stored in the second storage device, wherein the first storage system is coupled to the second storage system via a storage area network (SAN) and communicates therewith according to a block input/output (I/O) interface, wherein the first storage system is coupled to the computer via a local area network (LAN) and communicates therewith according to a file I/O interface, wherein each of the first storage device and the second storage device configures a plurality of logical volumes, wherein the second storage system is of a type different from the first storage system, and when a request to access the second file system is received from the computer, the first controller converts the request into a command for a logical volume of the second storage device, and the second controller sends the command to the second storage system, via the third controller, wherein the memory stores a volume management table, which comprises: a logical volume identifier that identifies each of the plurality of logical Volumes, wherein each of the plurality of logical volumes stores only files that were created on a same date; a Write Once Read Many (WORM) identifier that provides a WORM attribute indicating whether a write only once and a read many times operation is permitted for each of the plurality of logical volumes; and a file system identifier that identifies either a primary file system or a secondary file system corresponding to each of the plurality of logical volumes, wherein the primary file system is stored in the first storage system and the secondary file system is stored in the second storage system, wherein the volume management table further comprises, for each of the plurality of logical volumes other than the logical volume corresponding to a primary file system comprising the first file system, a date that indicates when files were stored in the primary file system, wherein at a second date, the files stored in the primary file system on a first date are migrated from the first storage system to the secondary file system in the second storage system, wherein after migration at the second date, the management terminal updates the file system identifier in the volume management table to indicate that the files migrated from the primary file system are now stored in the secondary file system, and updates the WORM identifier corresponding to the files stored on the first date to indicate that the write only once and a read many times operation is permitted for the files stored on the first date, and the secondary file system is mounted on the first file system such that the migration is not recognized by the computer, and wherein the single directory tree has a total capacity including a capacity of the first storage device and a capacity of the second storage device, and the computer has a transparent single view of the second file system without being aware of whether the second file system resides in the first storage system or the second storage system.