Disk array system capable of taking over volumes between controllers

• US 7,409,508 B2
• Filed: 08/29/2005
• Issued: 08/05/2008
• Est. Priority Date: 11/28/2001
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Takamoto, Kenichi, Mizuno, Yoichi, Mimatsu, Yasuyuki, Matsunami, Naoto
• Primary Examiner(s): PEIKARI, BEHZAD
• Application Number:
  US11/215,157
• Publication Number:
  US 20050283569A1
• Time in Patent Office: 1,072 Days
• Field of Search: None
• US Class Current: 711/154
• CPC Class Codes: G06F 11/2033 switching over of hardware resources
• CPC Class Codes: G06F 11/2092 Techniques of failing over between control units
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 2206/1012 Load balancing
• CPC Class Codes: G06F 2212/262 configured as RAID
• CPC Class Codes: G06F 2212/284 being distributed
• 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 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0617 in relation to availability
• CPC Class Codes: G06F 3/0629 Configuration or reconfiguration of storage systems
• CPC Class Codes: G06F 3/0635 by changing the path, e.g. traffic rerouting, path reconfiguration
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/065 Replication 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 disk array system of the type that each controller has an independent and dedicated cache. The disk array system can change control of a desired volume between desired controllers without suspending the system. When volumes are taken over between controllers, a switch-source controller de-stages data of a subject volume on the data cache to a storage subject disk to maintain the disk content reflection (coherency). Even if each controller has an independent and dedicated cache, a desired volume can be taken over between desired controllers without suspending the system. Each controller has a configuration manager which stores the controller number of a switch-destination controller to allow automatic volume take-over and automatic control by the original controller.

Claims

1. A data storage system comprising:

at least one computer; and

a memory system to be used by said at least one computer;

said memory system comprising;

a first controller having a first dedicated cache;

a second controller having a second dedicated cache; and

a plurality of disk apparatuses coupled to said first controller and to said second controller;

said first controller operative to control a plurality of first logical units defined among said disk apparatuses,

said second controller operative to control a plurality of second logical volumes defined among said disk apparatuses,

said first controller and said second controller operative to manage configuration information of said first logical volumes and said second logical volumes,

said first controller operative to change said configuration information to transfer control of at least one of said first logical volumes to said second controller.

2. A data storage system according to claim 1 further comprising a path control unit configured to provide access between said at least one computer and said logical volumes, wherein when said first controller transfers control of said at least one of said first logical volumes to said second controller, said path control unit provides access between said at least one computer and said second controller in order to access said at least one of said first logical volumes.

3. A data storage system according to claim 2, wherein said path control unit switches an access path of said at least one of said first logical volumes from said first controller to said second controller.

4. A data storage system according to claim 3, wherein after an access path of said at least one of said first logical volumes is switched from said first controller to said second controller, said path control unit resumes access from said at least one computer to said at least one of said first logical volumes.

5. A data storage method in a storage system comprising a plurality of logical volumes, the method comprising:

in a first controller, controlling a plurality of first logical volumes to service data access requests from a first computer;

in a second controller, controlling a plurality of second logical volumes to service data access requests from said first computer;

managing configuration information of said first logical volumes and said second logical volumes;

modifying said configuration to transfer control of at least one of said first logical volumes to said second controller, wherein said second controller subsequently controls said at least one of said first logical volumes to service data access requests from said first computer.

6. A data storage method according to claim 5 further comprising, in response to a data access request from said first computer to access said at least one of said first logical volumes, directing said data access request to said second controller subsequent to said first controller transferring control of said at least one of said first logical volumes to said second controller.

7. A data storage method according to claim 6 further comprising switching an access path of said at least one of said first logical volumes from said first controller to said second controller.