News Column

Patent Application Titled "Dynamically Varying the Number of Database Replicas" Published Online

July 1, 2014

By a News Reporter-Staff News Editor at Information Technology Newsweekly -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors Guo, Qun (Bellevue, WA); Mani, Pradeep (Bellevue, WA); Kalhan, Ajay (Redmond, WA), filed on December 10, 2012, was made available online on June 19, 2014.

The assignee for this patent application is Microsoft Corporation.

Reporters obtained the following quote from the background information supplied by the inventors: "Large scale data centers typically comprise organized clusters of hardware running collections of standard software packages, such as web servers, database servers, and the like. Distributed computing services may be provided using devices on a network comprising multiple interconnected data centers. Database replication services allow a service provider to maintain one or more backup copies of their data at multiple locations on the network. Existing data backup solutions enable a user to store backup information in a location and/or on media that are separate from an original source. Data from one machine may be backed-up or replicated to separate databases at remote network locations. This replicated data can be retrieved to restore a database or service in the event of a failed machine.

"In a cloud computing environment, for example, a service may use a predetermined number of replicas for all databases, such as a primary replica and one or more secondary replicas. Each database replica is maintained on a separate machine, which is often located remote from machines hosting other replicas of the same data. When a machine fails and does not come back online for a considerable amount of time, such as two hours, the replica stored on the failed machine will be lost and must be rebuilt. The larger the amount of data that is lost, the more time it will take to rebuild the lost replica. During the time it takes to rebuild the lost replica, there are only two replicas available. This further increases the risk of data loss if the primary replica or a secondary replica fails while the lost replica is being replaced."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

"Embodiments of the invention dynamically vary the number of replicas based on certain conditions to protect users from data loss. The size of the database is one condition that can be used to determine the number of replicas required.

"Typically, a database system may create three replicas--such as a primary replica and two secondary replicas. When the database size exceeds a first threshold, a fourth replica may be created. The fourth replica is maintained as long as the database size is above a second threshold that is smaller than the first threshold. However, when the database shrinks below the second threshold, then the fourth replica is deleted. Using two different thresholds in this manner prevents the system from frequently cycling between three and four replicas.


"To further clarify the above and other advantages and features of embodiments of the present invention, a more particular description of embodiments of the present invention will be rendered by reference to the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

"FIG. 1 illustrates a system for maintaining a variable number of database replicas according to one embodiment.

"FIG. 2 is a flowchart illustrating a method or process for managing the number of replicas created for a database based upon database size.

"FIG. 3 is a flowchart illustrating a method or process for managing the number of replicas created for a database according to another embodiment.

"FIG. 4 illustrates an example of a suitable computing and networking environment for managing the number of database replicas."

For more information, see this patent application: Guo, Qun; Mani, Pradeep; Kalhan, Ajay. Dynamically Varying the Number of Database Replicas. Filed December 10, 2012 and posted June 19, 2014. Patent URL:

Keywords for this news article include: Microsoft Corporation, Information Technology, Information and Data Loss and Recovery.

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Source: Information Technology Newsweekly

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