1. Abstract …………………………………………………………… 3

2. Glossary ……………………………………………….…………... 4

3. Introduction ………………………………….…………………… 5

4. Types of Backup and Synchronization

4.1 Backup ……………………………..…………………………….. 6

4.2 One Way Synchronization………………………………………... 6

4.3 Two Way Synchronization …..………………………………….. 6

4.4 One to Many Synchronization ………………………………….. 7

4.5 Many to One Synchronization ………………………………….. 7

4.6 Mirroring …………………………….………………………….. 7

4.7 Move Synchronization ……………..…………………………….. 8

4.8 One time Synchronization ………………………………………. 8

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1. Abstract

The expanding scope of Automation results in a large increase of personal information in the electronic format. This proliferation of personal information results in a difficulty of maintaining replicated copies of the user data in the data stores. Backup is an automated action of replicating critical data. Synchronization is an automated action to make the replicated data be consistent with each other and up-to-date.

In this paper we will be discussing the different types of Backup and Synchronization are generally available in the industry today.

2. Glossary

Source File: The primary user file.

Destination File: A copy of the source file at a secondary location.

Source Computer (Source): Source computer is the computer on which the source file resides.

Destination Computer (Destination): Destination Computer is the computer on which the destination file resides.

Backup: Backup is the automated process of making the destination file same as the source file by overwriting the destination file with the source file.

Synchronization: Synchronization is the process of overwriting the older of source or destination file by the latest version.

Source Network: Source Network is the network in which source computer resides.

Destination Network: Destination Network is the network in which the destination computer resides.

Link: Link is the type of connection between source and destination computer. It can be a LAN, WAN or wireless.

Source Process: Source process is the process running on the source computer which backups or synchronizes the source file to the destination file.

Destination Process: Destination process is the process running on the destination computer which helps in backing up or synchronizing the source file and the destination file. The destination process is optional for many differencing techniques.

3. Introduction

Depending on the needs, the design of the Backup and Synchronization may change from, organization to organization and from, person to person within the organization. This document describes the different Backup and Synchronization patterns which users can create in a generic way.

4. Types of Backup and Synchronization

4.1 Backup

Backup is the automated process of making the Destination (consisting of files and folders) same as the Source(consisting of files and folders). There are some variants to the backup scenario to deal with a situation when a file is deleted from the source. If a file gets deleted from the Source then it may be deleted from the destination, left at the destination or exist in the destination for some grace period after which it is deleted. Also, the destination may contain the whole history or archive of the source file, instead of the latest version of the file. Users may backup data to more than one destination to have some sort of redundancy.

Primary reason: The primary reason of using Backup is to secure the primary data.

4.2 One Way Synchronization

One Way Synchronization is similar to Backup i.e. it is an automated process in which we make the Destination File same as the Source File. The main difference between Backup and One Way Synchronization is that in one way synchronization, we assume that the destination exists not just for storage purpose but is a live version that is being used by some other user who is expected to view the files but is not expected to make any changes to it.

Primary reason: To keep data available in two locations, but if changes happens, changes from the primary location are committed.

4.3 Two Way Synchronization

Two Way Synchronization is an extension of One Way Synchronization. In Two Way Synchronization we update either the Source (or first location) or the Destination (or the second location) with the latest of the two or some other well defined rule. In two way synchronization, if both the source and destination are changed, then it leads to a conflict which needs to be resolved by user or through conflict resolution rules that can be preconfigured (e.g. latest wins or the first location wins).

Primary reason: To keep data available in two locations, and changes from either side to be committed.

4.4 One to Many Sync (one way)

One to Many Synchronization is needed when we have one Source file and more than one Destination files. We always update the Destination files to make them same as the Source file. We may archive the file in one or more of the destinations in One to Many Synchronization pattern.

Primary reason: The primary reason for using One to Many sync is for distribution.

4.5 Many to One Sync (one way)

In Many to One Synchronization, we have many versions of the Source file and only one Destination file. We may archive the file in Many to One Synchronization pattern in the single destination.

Primary reason: The primary reason for using Many to One Sync is to accumulate files from different sources in one location.

4.6 Mirroring

In Mirroring, more than one locations are replicated (i.e. made to look exactly the same) after the synchronization takes place by taking the latest changes from all the places. In mirroring, if two locations are changed simultaneously, then it leads to a conflict which needs to be resolved by user or through conflict resolution rules that can be preconfigured (e.g. latest wins or the first location wins).

Primary Reason: This pattern is useful for clustering and load balancing applications by maintaining a replica of a given site.

4.7 Move

In Move, we destructively transfer the Source File to Destination File i.e. we make the Source file same as the Destination file and then we delete the Source file.

The Move pattern can be used in association with One to Many pattern or Many to One pattern.

Primary reason: This pattern is primarily used when data is temporarily created in a location where it should not reside and therefore is changed to its actual destination.

4.8 One Time Synchronization

One Time Synchronization is a special type of Synchronization in which Destination file is made same as the Source file only once as after the synchronization, definition of the project itself is removed

One Time Synchronization can be used in conjunction with any of the other patterns.

Primary reason: The primary reason for using One Time Sync is when the data location has permanently changed so we want to move the data from old source to new location once and then forget about the old location.