Enterprise Vault™ Introduction and Planning

Enterprise Vault single instance storage works on the following principles:

• Vault stores are grouped within vault store groups. A vault store group forms the outer boundary for sharing with single instance storage.

• Each vault store is assigned a sharing level, which is one of "Share within group", "Share within vault store" or "No sharing".

• Enterprise Vault archives an item using single instance storage if the target vault store has a sharing level of "Share within vault store" or "Share within group".

• A vault store's sharing level determines the vault store's sharing boundary, as follows:

  • If a vault store's sharing level is "Share within group", its sharing boundary includes all the vault stores in the group that have this sharing level.

  • If a vault store's sharing level is "Share within vault store", its sharing boundary contains only the vault store.

  • If a vault store's sharing level is "No sharing", the vault store has no sharing boundary. Enterprise Vault does not perform single instance storage for the vault store.

• Enterprise Vault identifies the parts of an item that are suitable for sharing, such as large message attachments. These parts are referred to as SIS parts. Enterprise Vault uses a minimum size threshold for SIS parts, to balance the likely storage savings against the resources that are required to create, archive, and retrieve them.

• Enterprise Vault stores each SIS part only once within the target vault store's sharing boundary. For each SIS part, Enterprise Vault accesses the vault store group's fingerprint database to determine whether a SIS part with the same fingerprint is already stored within the vault store's sharing boundary. A SIS part with the same fingerprint indicates an identical SIS part.

  • If an identical SIS part is not already stored within the sharing boundary, Enterprise Vault stores the SIS part and saves the SIS part's fingerprint information in the fingerprint database.

  • If an identical SIS part is already stored within the sharing boundary, Enterprise Vault references the stored SIS part. It does not store the SIS part again.

• Enterprise Vault stores the remainder of the item (the item minus any SIS parts) as the residual saveset file. The residual saveset file holds Enterprise Vault metadata about the item and unique information about it, such as the file name if it is a document or attachment, and follow up flags if it is a message.

• When Enterprise Vault receives a request to restore an archived item, it reconstitutes the item from the item's residual saveset file and SIS part files.

• Vault stores 1, 3, and 4 all have the sharing level "Share within group". These vault stores are within the same sharing boundary. Enterprise Vault shares SIS parts across the three vault stores for items it archives to these vault stores.

• Vault store 2 has the sharing level "Share within vault store", so it has its own sharing boundary. Enterprise Vault shares SIS parts within the vault store for items it archives to the vault store.

• Vault store 5 has the sharing level "No sharing". The vault store is not included in any sharing boundary. Enterprise Vault does not perform Enterprise Vault single instance storage on the items that it archives to this vault store.

Single instance storage can save storage space in a number of ways:

• If you use separate vault stores for journaling and mailbox archiving, Enterprise Vault can share the SIS parts between the vault stores, provided that they are in the same sharing boundary.

• If a number of separate messages with the same large 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 large 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.

Note the following:

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

• Smart partitions. Enterprise Vault shares the SIS parts between items in the same smart partition, but it does not share the SIS parts between a smart partition and other partitions.

  For example, suppose that two employees receive the same email, which has an attachment. For compliance reasons, Enterprise Vault archives one employee's emails to a smart partition; it archives the other employee's emails to the standard vault store partition. If Enterprise Vault first archives the email and its attachment to the standard partition then, when it subsequently archives the email to the smart partition, it should not normally archive the attachment again. This would mean that the data on the smart partition is not fully compliant, however, so in this case Enterprise Vault archives both the email and the attachment again.