Single-instance storage is a system's ability to keep one copy of content that multiple users or computers share.

The primary advantages of being file-based is hardware independence and single-instance storage of a file referenced multiple times in the filesystem tree.

Novell GroupWise was built on single-instance storage which accounts for the large data stores that GroupWise is able to achieve.

The file-based Windows Imaging Format introduced in Windows Vista also supports single-instance storage.

Single-instance storage has been a feature of Microsoft Exchange Server since version 4.0 and is also present in Microsoft's Windows Home Server.

Due to the use of single-instance storage, the more each successive disk image has in common with previous images added to the WIM file, the less new data will be added.

In the case of an e-mail server, single-instance storage would mean that a single copy of a message is held within its database whilst individual mailboxes access the content through a reference pointer.

Centralized backup - Allows backup of up to 10 PCs, using Single-instance storage technology to avoid multiple copies of the same file, even if that file exists on multiple PCs.

First used by Microsoft in Exchange Server, single-instance storage eliminates duplicated files and minimizes the size of Windows Home Server's backups by keeping only one copy of files used by multiple users or computers -a process Microsoft refers to as Single Instance Store.