Client-server system with parity storage

• US 5,630,007 A
• Filed: 03/25/1996
• Issued: 05/13/1997
• Est. Priority Date: 03/30/1995
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Kobayashi, Tsuyoshi, Yamaguchi, Tomohisa, Minemura, Harumi, Nakamura, Shunichiro
• Primary Examiner(s): Chin, Tommy P.
• Assistant Examiner(s): Lee, Y.
• Application Number:
  US08/621,227
• Time in Patent Office: 414 Days
• Field of Search: 386/46, 386/45, 386/125, 348/7, 348/13, 348/12, 455/5.1, 395/200.08, 395/200.09, 395/200.05
• US Class Current: 386/265
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/16 Error detection or correction of the data by redundancy in hardware
• CPC Class Codes: G06F 11/2087 with a common controller
• CPC Class Codes: G06F 2211/1028 Distributed, i.e. distributed RAID systems with parity
• CPC Class Codes: G06F 2211/1057 Parity-multiple bits-RAID6, i.e. RAID 6 implementations
• CPC Class Codes: H04N 21/2182 involving memory arrays, e.g. RAID disk arrays RAID arrays per se G06F3/0689; use of parity to protect data in RAID systems G06F11/1008
• CPC Class Codes: H04N 7/17336 Handling of requests in head-ends

Abstract

The invention relates to a client-server system which improves efficiency of each server by distributing loads to a plurality of servers. The a client-server system comprises a plurality of storages for sequentially storing data which are distributed in each of the plurality of storages; a plurality of servers, each of which is connected to the plurality of storages, for accessing the data distributed and stored in each of the plurality of storages; an administration apparatus which is connected to the plurality of servers for administrating the data sequentially stored in the plurality of storages, and the plurality of servers; and a client which is connected to both the administration apparatus and the plurality of servers, the clients specifies a server which is connected to a storage where a head block of the data is stored by inquiring to the administration apparatus, and accesses the data in the plurality of servers according to the order of the data storage sequence from the specified server.

Claims

1. A client-server system comprising:

(a) a plurality of storage devices for storing data wherein said data is distributed in said plurality of storage devices;

(b) a plurality of servers, each of which is connected to a portion of said plurality of storage devices, for accessing said data;

(c) an administration apparatus which is connected to said plurality of servers, the administration apparatus comprises;

(c1) an administration means for administrating said data stored in said plurality of storage devices, and said plurality of servers;

(c2) a parity storage device for storing parities;

(c3) an inter-server parity generation means for generating parities from said data stored in said plurality of storage devices connected to said plurality of servers, and for storing said generated parities into said parity storage device; and

(c4) an inter-server restoration means for restoring data which are stored in an inaccessible storage device connected to a server, using data which are stored in accessible storage device and parities which are stored in said parity storage device, when any one of said plurality of storage devices becomes inaccessible, and for storing said restored data into said parity storage devices; and

(d) a client which is connected to both said administration apparatus and said plurality of servers, wherein said client comprises;

(d1) an access demand means for specifying a server, identified by said administration apparatus, which is connected to a storage device where a head block of said data is stored, and for accessing said data through said plurality of servers according to an order in which said data is distributed in the plurality of storage devices after said specified server, and for informing the inter-server restoration means of a location of said inaccessible storage device connected to a server when any one of said plurality of servers fails to access said data; and

(d2) an inter-client restoration means, for restoring data which are stored in an inaccessible storage device, using data which are stored in accessible storage devices and parities which are stored in said parity storage device, before the data are restored by said inter-client restoration means, and for accessing restored data which are stored in said parity storage devices after said data are restored by said inter-client restoration means.

2. The client-server system of claim 1, wherein:

said administration means comprises a standby storage device for storing parities;

said inter-server restoration means includes a means for copying said parities stored in said parity storage device into said standby storage device before restoring data; and

said inter-client restoration means includes a means for restoring data stored in any one of said storage devices connected to an inaccessible server, using data stored in said storage devices connected to other servers and parities copied in said standby storage device, when said inter-server restoration means is restoring data.

3. The client-server system of claim 1, wherein:

said administration apparatus comprises a second inter-server parity generation means for generating parities from said data which are distributed and stored in said plurality of storage devices connected to said plurality of servers, and for distributing and storing said generated parities in each of said plurality of storage devices.

4. The client-server system of claim 3, wherein:

said administration apparatus comprises a second inter-server restoration means for restoring data stored in any one of said storage devices connected to an inaccessible server, using data stored in said storage devices connected to accessible servers and parities distributed and stored in each of said plurality of storage devices connected to said plurality of servers, when any one of said plurality of servers fails to access said data.