System and method of an efficient snapshot for shared large storage

• US 7,085,899 B2
• Filed: 07/03/2003
• Issued: 08/01/2006
• Est. Priority Date: 10/24/2002
• Status: Expired due to Fees

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Kim, Chang Soo, Kim, Young Ho, Kang, Dong Jae, Shin, Bum Joo, Bak, Yu Hyeon, Kim, Myung Joon
• Primary Examiner(s): Padmanabhan, Mano
• Assistant Examiner(s): Walter, Craig E
• Application Number:
  US10/612,000
• Publication Number:
  US 20040083345A1
• Time in Patent Office: 1,125 Days
• Field of Search: None
• US Class Current: 711/161
• CPC Class Codes: G06F 11/1466 to make the backup process non-disruptive
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

An efficient snapshot technique based on a mapping for a large logical volume shared in multiple hosts. According to the present invention, problems of time delays in a conventional snapshot technique is solved by employing a FAB and an SSB, which are bits representing whether a COW operation is carried out to a mapping entry. In other words, the present invention solves the problems of delaying a write operation of corresponding volume, which is simultaneously executed when a snapshot is created, until the snapshot creation is completed.

Claims

1. A system based on a storage array network (SAN), the system comprising:

a plurality of hosts configured to share a large network storage, and an original mapping table and a snapshot mapping table being stored in the same disk of a logical volume in the network storage,

wherein a snapshot volume is added, and a data block is allocated on the same disk if a copy-on-write (COW) operation is carried out, and

wherein a mapping entry of the original mapping table includes a physical data block information and a snapshot status information.

2. The system according to claim 1, wherein the snapshot status information of the mapping entry is a snapshot status bit (SSB) and a first allocation bit (FAB).

3. A storage array network (SAN) system comprising:

a plurality of hosts configured to share a large network storage;

an original mapping table stored in a disk of a logical volume in the network storage; and

a snapshot mapping table stored in the same disk of the logical volume in the network storage;

wherein a snapshot volume is added, and a data block is allocated on the same disk if a copy-on-write (COW) operation is carried out, and

wherein a mapping entry of the original mapping table includes a physical data block information and a snapshot status bit (SSB) and a first allocation bit (FAB).