About Enterprise Vault single instance storage

Enterprise Vault's optimized single instance storage can provide a significant reduction in the storage space that is required for archived items. Enterprise Vault identifies the shareable parts (SIS parts) of an item, such as a message attachment or the contents of a document. It stores each SIS part separately, and only once within a sharing boundary. A sharing boundary can include one or more vault stores within a vault store group. When Enterprise Vault identifies a SIS part that it has already stored in the target vault store's sharing boundary, it references the stored SIS part file instead of archiving the SIS part again.

Enterprise Vault applies a minimum size threshold for SIS parts. The size threshold enables Enterprise Vault to balance the likely storage savings against the resources that are required to create, archive, and retrieve the SIS parts.

Enterprise Vault single instance storage can save storage space in a number of ways:

Enterprise Vault shares the SIS parts between all the vault stores within a sharing boundary. For example, if you use separate vault stores for journaling and mailbox archiving, Enterprise Vault can share the SIS parts between the vault stores.
If a number of separate messages with the same attachment are sent to multiple recipients, Enterprise Vault stores the attachment only once within a sharing boundary.
Enterprise Vault identifies a SIS part from the content, not the file name. If two messages both have the same file attachment, Enterprise Vault can share the attachments, even if they have different file names.
Enterprise Vault can share the identical SIS parts that result from different types of archiving, such an Exchange message attachment that is also stored as a file on a file server.

If you upgrade to Enterprise Vault 8.0, Enterprise Vault creates a Default Upgrade Group for each Enterprise Vault site, and places the site's existing vault stores in that group. The Default Upgrade Group does not use single instance storage until you configure sharing for it.

In any other vault store group, a new vault store uses Enterprise Vault single instance storage by default. The vault store shares only the SIS parts of the items that are archived within itself, by default. It does not share the SIS parts of the items that are archived to other vault stores in the vault store group.

You can run the Configure Sharing wizard on a vault store group to extend sharing between vault stores, or to turn off Enterprise Vault single instance storage if you want.

Note:

Enterprise Vault single instance storage is not performed when items are stored to partitions that are hosted on EMC Centera devices. Enterprise Vault provides a separate device-level sharing option to take advantage of the sharing capabilities of EMC Centera devices.

See About EMC Centera device-level sharing.

For more information on Enterprise Vault single instance storage, see the following topics: