Domino Attachment and Object Service - IBM Lotus Notes

Domino Attachment and Object Service was introduced in version 8.5 to address the space issue on Mail and Application servers. In previous versions of Lotus Notes, and later, Domino, there was an implementation of the Single Copy Object Store (SCOS) that could be employed to reduce the overall footprint of the mail environment. The functional limitations and administrative overhead made the implementation of this technology very difficult in large organizations. With the introduction of DAOS, small and large organizations will be able to gain the benefits of a reduced footprint to deliver an enhanced environment in a more cost-effective manner. The following sections will provide an overview of the DAOS technology and some high-level implementation steps.

The DAOS technology is a process by which the Domino server identifies messages that contain an attachment and then shifts that attachment to the file system in the form of a Notes Large Object (NLO) that is stored in a subdirectory on the server. A reference to the NLO is placed in the end users' mail database, rather than the attachment itself being stored in the mail database. If an attachment is sent to multiple users, references are placed in all of the mail databases, and only one copy of the attachment is stored on the server. If that message is replied to, or forwarded, the reference is included and not the attachment. It is important to note that DAOS stores the attachments on a per server basis. So, if there are four users who sent the message, and if three of the users are located on one server and one of them is located on another server, two copies of the attachment will be placed within DAOS, on separate servers. To aid in the effectiveness of DAOS, grouping the users on a server by department or by functionality is optimal, but not necessary.

Domino Attachment and Object Service

The DAOS manages the attachments within the environment from the time a new mail arrives. As shown in the following diagram, when a new message arrives at the server, the DAOS removes the attachments from the message for all recipients whose databases are participating in DAOS, creates and moves an NLO file to the DAOS subdirectory, and places a reference in the header of the message:

Domino Attachment and Object Service

Advantages of DAOS

A test by Lotus has determined that most Domino environments can achieve savings when DAOS is implemented in the environment. These savings can range from very small numbers, if attachments are not used within the environment, to a very significant number, if end users send attachments extensively. The percentage of reduction to the storage environment will vary, so it is recommended that, prior implementing DAOS, the administration team run a utility to determine the impact.

The Domino development team has created the DAOS Estimator tool, which can perform a scan of all databases on the server and produce a report that will summarize the potential savings to be gained from implementing the tool

The Estimator tool provides a complete breakdown for every database in the environment; the following screenshot displays the summary information that is provided by the Estimator tool. When run on a production environment, the tool outlined a potential saving of 38 percent in storage, as a result of DAOS alone:

Advantages of DAOS

Setting up DAOS

Once you have determined that leveraging DAOS in your environment will be productive, it is important to properly configure the environment to support the service. It is important to understand that transaction logging is required to implement DAOS and must be enabled once DAOS is implemented. When a database on a server has DAOS enabled, the contents of the message, including the attachment, are included in the transaction log. If there is a failure on the server and the log is replayed, all of the contents will be written, including the attachment.

Once transaction logging is enabled in the environment, the next step is to ensure that all of the databases are at On-Disk Structure (ODS) 51. Other features available within Domino, such as compression, require a minimum of ODS 48. Once the ODS is at the proper level, the DAOS service needs to be enabled and configured on the server. To configure the DAOS service, the server configuration document will need to be modified. Please keep in mind that the server will need to be recycled for the settings to take effect; make sure that enabling the service fits within your maintenance windows and the settings have been tested to ensure no end user impact.

Locate the server configuration document that you want to enable DAOS on. Open the server configuration document. Go to the DAOS tab and click on the Edit Server button.


Click on the Store file attachments in DAOS drop-down box and change it to Enabled. This will expose three additional fields, as shown in the following screenshot. You can configure a minimum size for attachments to participate in the service, and the location of the DAOS path. The DAOS directory can be housed outside of the data directory.

Server: caddyshack01/servers

The next step is to enable DAOS on the databases that are intended to leverage the service. In the administrator client on the Files tab, highlight the databases and click on the Advanced Properties... button.

DAOS on the databases

In the Advanced Database Properties dialog box, locate the Use Domino Attachment and Object Service option and select it (see the following screenshot). This will include the database in the DAOS service. Once this option is set, the database will have its attachments referenced by the DAOS service. If this option is removed later, the DAOS server will continue to manage attachments for the database until the compact -c -daos off command is executed on the database. This will bring the attachments back into the database:

DAOS on the databases

Now the server has been configured and all current databases that need to be included in the DAOS server have also been configured. To enable new databases to be included in the DAOS environment, the notes.ini file needs to be modified to include this Create_ R85_ Databases=1. Once this setting is included, newly created databases will be included.

To this point, the server is configured for DAOS, the current databases have been set to be included in the service, and all future databases will be included, but no legacy data has been moved to the service to start the process of saving data. To include current data on the DAOS server, from the administration clients' server console, execute the load compact -c -daos on command, as shown in the following screenshot:

load compact -c -daos on command

The implementation of DAOS does not have an impact on the quota or limits that are put in place within the environment. The logical size of a mail file will include the elements that are stored in the DAOS service. For example, if a user's mail database is identified as 260 MB, the actual physical size of the database on the server may be 150 MB.

All rights reserved © 2018 Wisdom IT Services India Pvt. Ltd Protection Status

IBM Lotus Notes Topics