Method of data migration

• US 6,374,327 B2
• Filed: 02/14/2001
• Issued: 04/16/2002
• Est. Priority Date: 12/11/1996
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ishikawa, Takehiro, Nishijima, Hiroshi, Hatanaka, Toshiaki, Sakaki, Hidetoshi, Nakamura, Katsunori, Kurano, Akira
• Primary Examiner(s): Bragdon, Reginald G.
• Application Number:
  US09/782,080
• Publication Number:
  US 20010011324A1
• Time in Patent Office: 426 Days
• Field of Search: 711/112, 711/162
• US Class Current: 711/112
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

A method, apparatus and computer program for controlling data migration in an information processing system which includes a central processing unit (CPU), a new storage system connected to the CPU and an old storage system connected to the new storage system. In the information processing system data migration is conducted to transfer data from the old storage system to the new storage system. The invention operates by permitting access by the CPU to the storage systems during data migration. When an access by the CPU is generated the invention determines whether the access is to a region where data migration has been completed or to a region where data migration has not been completed. If the access is to a region where data migration has been completed, then processing of the access is handled by the new storage system. If the access is to a region where data migration has not been completed, then processing of the access is handled by the old storage system causing data related to the access to be transferred from the old storage system to the new storage system. The speed of data migration can be adjusted based upon the utilization of the resources of the information processing system and information of the priority of access to the new storage system by the CPU.

Claims

1. A method of controlling data migration in an information processing system which includes a CPU, a new storage system coupled to said CPU and an old storage system coupled to said new storage system, wherein data migration is conducted to transfer data from said old storage system to said new storage system, said method comprising:

permitting access to said storage systems by said CPU during data migration;

determining whether said access is to a region where data migration has been completed based on a copy pointer;

processing said access to said new storage system when said access is to a region where data migration has been completed; and

processing said access to said old storage system and transferring data related to said access from said old storage system to said new storage system when said access is to a region where data migration has not been completed,

wherein said processing said access to said new storage system comprises;

checking whether said access is a READ access or a WRITE access,

when said access is a READ access, transferring data related to said access from said new storage system to said CPU, and

when said access is a WRITE access, transferring data related to said access from said CPU to both said new storage system and said old storage system.

2. A method according to claim 1, wherein said copy pointer indicates the position of data migration.