How attachment consolidation works

The information in this topic describes what happens to an attachment during consolidation.

• An administrator enables the feature for an entire Domino® server on the DAOS (Domino® Attachment and Object Service) tab in the Server document.
• A database administrator, administrator, or full access administrator sets the Use Domino Attachment and Object Service database property to include one or more existing databases in consolidation, or any user creates a new database from a template whose DAOS property is enabled and ready to be inherited.
• In any DAOS-enabled database, a user saves a document containing one or more file attachments larger than the size specified on the DAOS tab.
• The Domino® server stores a reference (called a ticket) to the file attachment in the object header of the document, and stores a single copy of the file attachment in the attachment repository on the server.
• When any user opens the document again, the header activates a link to the stored file attachment. The file attachment displays as if the file were actually stored in the document.
• If a user edits the document and saves a new version of the attachment, Domino® adds the revised copy of the file attachment to the attachment repository, deletes the reference in the document to the original file attachment, and creates a new reference to the revised attachment.
• If users later create multiple documents (such as replies in an email thread) containing copies of the same file attachment, the Domino® server places a reference in every document to the single copy of the file attachment in the repository.
• If a user later deletes the attachment, Domino® deletes only the reference in the document header. The file attachment in the repository is not affected as long as it is still used by other documents.
• If all users delete the attachment from all documents to which it had been attached, Domino® marks the file for removal from the attachment repository. The attachment is actually removed after the specified number of days for deferred deletion (by default, 30 days). As an administrator, you can use a DAOS Manager Tell command to specify a different number of days or even to remove attachments immediately. However, the deletion interval provides extra insurance in case of a server failure that might require restoring attachments from backup sources.
• As an administrator, you can use the Files tab in the Domino® Administrator client to see information on the size of the database after it participates in DAOS. For example, after you have customized the Files tab to add the DAOS Size column, you can see that the value in the Physical Size column plus the value in the DAOS Size column equals the value in the Logical Size column. The logical size is used to determine quotas for mail databases and describes the space that is reserved for the database in the system. But the physical size, after the DAOS size is subtracted, is much smaller and can help you determine the actual disk space savings you achieve on a Domino® server by using DAOS.