DATA SYNCHRONIZATION AMONG FILE STORAGES USING STUB FILES

• US 20140379768A1
• Filed: 09/08/2014
• Published: 12/25/2014
• Est. Priority Date: 12/14/2010
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: MATSUZAWA, Keiichi
• Granted Patent: US 9,460,106 B2
• Time in Patent Office: Days
• US Class Current: 707/827
• CPC Class Codes: G06F 16/119 Details of migration of file systems migration mechanisms in storage systems G06F3/0647
• CPC Class Codes: G06F 16/1744 using compression, e.g. sparse files
• CPC Class Codes: G06F 16/178 Techniques for file synchronisation in file systems
• CPC Class Codes: G06F 16/1787 Details of non-transparently synchronising file systems
• CPC Class Codes: G06F 16/185 Hierarchical storage management [HSM] systems, e.g. file migration or policies thereof details of archiving G06F16/11
• 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]

Abstract

A method switches file server from old file server to new file server which are coupled via a backend network and provides data synchronization. The old file server and new file server are coupled with one or more host computers via a frontend network to direct input/output (I/O) requests from the one or more host computers. The method comprises creating stub files in the new file server, the stub files including stub information indicating location of data in the old file server; switching I/O requests directed to old file server to I/O requests directed to the new file server; checking whether the new file server has any stub files; and, if the new file server has one or more stub files, recalling data corresponding to the one or more stub files from the old file server according to the stub information to replace the one or more stub files.

Claims

1. A first file server comprising:

an interface coupled to a second file server which manages a second file tree on a second file system; and

a processor being configured to create a first file tree, which corresponds to the second file tree and includes one or more stub files, on a first file system based on metadata of the second file tree, and obtain file data corresponding to the one or more stub files from the second file system in the second file server;

wherein upon receipt of a request for a file of the first file tree during creating the first file tree and while obtaining the file data corresponding to the one or more stub files, the processor is configured to obtain a part of the metadata of the second file tree and file data corresponding to the requested file to respond to the received request.