Hierarchical RAID system including multiple RAIDs and method for controlling RAID system

• US 6,651,137 B2
• Filed: 03/28/2001
• Issued: 11/18/2003
• Est. Priority Date: 12/30/2000
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Ahn, Dae-Young, Baek, Sung-Hoon
• Primary Examiner(s): PORTKA, GARY J
• Application Number:
  US09/818,762
• Publication Number:
  US 20020124139A1
• Time in Patent Office: 965 Days
• Field of Search: 711/114, 711/117, 714/5, 714/6
• US Class Current: 711/114
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 2003/0697 device management, e.g. handlers, drivers, I/O schedulers
• CPC Class Codes: G06F 2211/1045 Nested RAID, i.e. implementing a RAID scheme in another RAID scheme
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems

Abstract

In a data storage system based on large capacitance, high performance and high availability through a hierarchical construction of redundant arrays of expensive disks (RAID) and a method for controlling the storage system, in order to provide better reliability and more prominent performance than the traditional RAID, and more particularly, in a hierarchical RAID system provided with a plurality of RAIDs in which at least one RAID composed of a large number of disks is used as a virtual disk, and a method for controlling the RAID system, and further in a record medium capable of being read through a computer having a writing of a program to realize the inventive method; the hierarchical RAID system includes a host computing unit; at least one upper level RAID controlling unit having a first RAID Level X, for controlling a plurality of first lower level RAID controlling units having a second RAID Level Y in order to use a lower level RAID as a virtual disk; and the plurality of first lower level RAID controlling units having the second RAID Level Y, for controlling numerous member disks under a control of the upper level RAID controlling unit so as to be used as the virtual disk of the upper level RAID.

Claims

1. A method for controlling a hierarchical RAID system having a plurality of RAIDs in which at lest one RAID composed of a plurality of disks is used as a virtual disk, said method comprising the steps of:

a) giving a read-command of existing data and parity from an upper level RAID controlling unit to a lower level RAID controlling unit when a write-command for new data is given from a host computer;

b) performing an exclusive OR of the new data, existing data and the parity, and executing a write-transmission in the lower level RAID controlling unit so as to perform a renewal of the parity and the data according to the execution result of the exclusive OR operation;

c)generating a command for reading the parity and data of a hard disk in the lower level RAID controlling unit according to the read-command of the step a), and transmitting the command to the upper level RAID controlling unit; and

d) evoking a reading for the data and a parity value and performing the exclusive OR so that the write-command given from the upper level RAID controlling unit becomes a write-transmission to each corresponding lower level RAID controlling unit, and executing the write-transmission for the renewal of parity and data.

2. A record medium capable of being read through a computer so as to use at least one RAID having a plurality of disks as a virtual disk, in a hierarchical RAID system having a microprocessor, the record medium characterized in that the computer has a writing of a program to realize:

a first function of giving a read-command for existing data and parity from an upper level RAID controlling unit to a lower level RAID controlling unit when a write-command for new data is given from a host computer;

a second function of performing an exclusive OR of the new data, existing data and the parity, and executing a write-transmission in the lower level PAID controlling unit so as to perform a renewal of the parity and the data according to the execution result of the exclusive OR operation;

a third function of generating a command for reading the parity and data of a hard disk in the lower level RAID controlling unit according to the read-command of the first function, and transmitting the command to the upper level RAID controlling unit; and

a fourth function of evoking a reading for the data and a parity value and performing the exclusive OR so that the write-command given from the upper level RAID controlling unit becomes the write-transmission to each corresponding lower upper level RAID controlling unit, and executing the write-transmission for the renewal of parity and data.