Continuous update of data in a data server system

• US 7,188,157 B1
• Filed: 06/30/2000
• Issued: 03/06/2007
• Est. Priority Date: 06/30/2000
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yamamoto, Masayuki, Yamamoto, Akira, Kodama, Shoji, Yamagami, Kenji
• Primary Examiner(s): Salad; Abdullahi
• Assistant Examiner(s): El-chanti; Hussein
• Application Number:
  US09/606,403
• Time in Patent Office: 2,440 Days
• Field of Search: 709/202, 709/203, 709/208, 709211-219, 709/221, 709/223, 709/220, 717/171
• US Class Current: 709/220
• CPC Class Codes: G06F 16/275 Synchronous replication
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1008 based on parameters of servers, e.g. available memory or workload monitoring of computer activity G06F11/30
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes

Abstract

A continuous update method includes reading out data from a first data store via a data switch to satisfy client requests for data. A second data store is updated via the data switch to contain new updated information. When it is desired to satisfy client requests with the new data, the second data store is copied to a third data store and subsequent client requests are satisfied from the third data store. Further updates are made to the second data store. The process is repeated, but the roles of the third and first data stores are reversed. In another embodiment of the invention, subsequent client requests are satisfied from the second data store and further updates are made to the first data store.

Claims

1. In a content server system for servicing client requests for content, including a plurality of Web servers connected to a plurality of clients and a storage device connected to the Web servers, a method of updating data thereof comprising:

providing a master disk storage component for updating data in response to write requests from an authorization server and first and second local disk storage components for retrieving data in response to read requests from the plurality of Web servers, the first and second local disk storage components and master disk component being hard disk drives in the storage device, data stored on the first and second local disk storage components and master disk component initially being synchronized so as to be mirror images of each other;

mounting the first local disk storage component to the plurality of Web servers, the plurality of Web servers operable to mount only one of the first and second local disk storage components at any time;

reading out data from the mounted first disk storage component in response to client read requests from the plurality of Web servers;

performing a first update of data in the master disk storage component in response to a write request from the authorization server, all write requests from the authorization server updating data in the master disk storage component;

receiving a synchronization signal;

in response to receiving the synchronization signal, copying data from the master disk storage component to the unmounted second local disk storage component in order to synchronize data between the master disk storage component, including updates from the authorization server, and the unmounted second local disk storage component, wherein the unmounted second local disk storage component becomes a mirror image of the master disk storage component;

in response to the unmounted second local disk storage component becoming a mirror image of the master disk storage component including updates from the authorization server, mounting the second local disk storage component to the plurality of Web servers and unmounting the first local disk storage component; and

reading out data from the mounted second local disk storage component in response to subsequently received client read requests from the plurality of Web servers.

2. The method of claim 1 wherein the step of reading out data from the first local disk storage component includes transmitting the data through a data switch.

3. The method of claim 2 wherein the step of copying includes transferring data over a data path exclusive of the data switch.

4. The method of claim 2 wherein the step of reading out data from the second local disk storage component includes transmitting the data through the data switch.

5. The method of claim 4 wherein the first step of updating includes transferring data through the data switch.

6. The method of claim 1 wherein some of the data in the first local disk storage component is contained in a cache memory and the step of reading out data includes reading out data from the cache memory.

7. The method of claim 6 further including unmounting the first local disk storage component and flushing the cache memory.

8. In a data server having a storage system for servicing client requests, a method for updating data contained in the storage system without interrupting service to clients, comprising:

providing a master data store for updating data in response to write requests and a first local data store and a second local data store for retrieving data in response to read requests, the master data store, first local data store, and second local data store initially being synchronized so as to be mirror images of each other;

mounting the first local data store to the storage system, the data storage system operable to mount only one of the first and second local data stores at any time;

(i) reading out data from the storage system via a data switch, the data being obtained from the mounted first local data store in the storage system, the first local data store being a first hard disk drive;

(ii) writing updated data to the master data store in the storage system via the data switch, the master data store being a second hard disk drive;

(iii) producing a first synchronization signal;

(iv) in response to the first synchronization signal, copying data from the master data store to the unmounted second local data store in the storage system to produce a mirror image of the data on the master data store on the unmounted second local data store, the second local data store being a third hard disk drive, mounting the second local data store to the data storage system in response to the unmounted second local data store becoming a mirror image of the master data store, and unmounting the first local data store;

(v) producing a second signal; and

(vi) in response to the second signal, reading data from the storage system via the data switch, the data being obtained either from the master data store or from the mounted second local data store.

9. The method of claim 8 wherein step (iv) occurs concurrently with step (vi).

10. The method of claim 8 wherein in step (iv) the data is written over a data path exclusive of the data switch.

11. The method of claim 8 further including a step (vii) of writing to an area on the master data store concurrently with step (iv).

12. The method of claim 11 wherein the step (vii) includes determining whether the area on the master data store to be written first needs to be written to the second local data store.

13. A content server system for providing content data to clients in response to read requests, comprising:

a storage system including a master data store and first and second local data stores, each data store being a hard disk drive, the data stored on the first and second local data stores and master data store being initially synchronized so as to be mirror images of each other, the master data store being provided for updating data in response to write requests and first local data store and a second local data store for retrieving data in response to read requests;

a data switch in data communication with the storage system;

a first data server in communication with the data switch and configurable to read data from a mounted first local data stores where the first data server is operable to mount only one of the first and second local data stores at any time; and

reading out data from the mounted first local data store in response to client requests;

an authoring server in data communication with the data switch for updating data on the master data store,

wherein the storage system is configured to transfer at least some of the contents of the master data store to the unmounted second local data stores in response to receiving a first synchronization signal from the authoring server, wherein a mirror image of data stored on the master data store is produced in the unmounted one of the first and second local data stores,

in response to the unmounted second local data store becoming a mirror image of the master of the master data store, the first data server is operable to mount the previously unmounted second local data store and unmount the first local data store, and read data from the previously unmounted second data store in response to receiving a second signal from the authoring server, and

wherein the authoring server produces updated data on the master data store and causes the updated data to be transferred directly to the unmounted first local data stores while the first data server provides data from the mounted second local data stores, thereby allowing update of data by the authoring server without interrupting data service to the clients.

14. The system of claim 13 wherein the storage system is further configured to transfer at least some of the contents of the master data store to the unmounted one of the first and second local data stores along a data path exclusive of the data switch.

15. The system of claim 13 wherein the storage system is further configured to detect the second signal and in response thereto to determine whether to provide data from the second local data store or from the master data store when the first server reads data from the second local data store.

16. The system of claim 13 wherein the data switch is a fibre channel switch.