What’s Single Instance Storage?

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Single-Instance Storage (SIS) is a method of reducing redundancy in computer systems by accessing a single file or asset by multiple users. Microsoft owns a patent on this technology, which is typically used in server systems like Microsoft Exchange Server. SIS reduces the size of hosting for documents and speeds up message delivery and processing.

Single-Instance Storage (SIS) is a method of organizing computer data by which a single file or asset within a system can be accessed by multiple users or “stores”. Microsoft® owns a patent on a particular application of this technology, which is typically used in server systems such as the Microsoft® Exchange Server® email organization service. In a computer system, multiple machines and users can be connected to a larger server that includes a host system. Instead of having each computer contain the same files and documents, a single instance storage system could be used to have these resources on the host system or “SIS common repository”.

The basic purpose of single instance storage is to reduce redundancy in a system by deleting multiple copies of something whenever possible. One of the easiest ways to do this is through an email server, such as Microsoft® Exchange Server®. In this system, multiple users can all have accounts, called “stores,” on the server through which to send, receive, and access e-mail.

When someone on this server sends an e-mail message to 100 other people on the same system, 100 copies are not actually generated. Through single-instance storage, each person is sent a “pointer” directing them to a single copy of the message. None of the recipients know about it, however, as the pointer looks just like the actual email.

This reduces the size of hosting for documents and speeds up message delivery and processing as the system requires less work. The use of single instance storage can extend to networks of computers and servers in other environments. Each computer on a system requires certain files to function, such as those needed by the operating system (OS). However, rather than each computer having all of these files, however, a single copy could be kept in a common archive and then the computers consult it as they are needed.

Single instance storage is usually transparent and many computer users may not even realize they are accessing it. For example, users of a network who share data are likely to continue to open and view files hosted on a common system in the same ways as anyone else. When they open the file, however, they are actually activating a “pointer” that appears to them as a file. This redirects their system to the real file in the SIS common repository. Single-instance storage can also be used on a smaller scale, allowing a system to better organize data for multiple users by eliminating file copies.




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