IBM Lotus Domino Object and Attachment Service (DAOS) is a feature introduced in Lotus Domino 8.5.0, aimed primarily at reducing disk space (you can read here more about it). If you wish to enable DAOS on your Server there are some considerations that you need (click on "read more" to read the full article).
Depending on your infrastructure you need to decide if you wish to encrypt the NLO files which are used by DAOS. Note that copying the NLO files from another Domino server will work only if DAOS encryption is turned off. DAOS encryption is on by default, and uses the server key to do the encryption; therefore encrypted NLO files are not portable between Domino servers. So if you backup files from multiple servers and use only one server to restore the files, then you need to turn the NLO DAOS encryption off. You need to turn DAOS also off if you use a cluster and wish to restore a application / database which exist on both server where DAOS is enabled.
The DAOS NLO encryption could be controlled via notes.ini entry DAOS_ENCRYPT_NLO:
DAOS_ENCRYPT_NLO=0 <-- Disable DAOS NLO encryption
DAOS_ENCRYPT_NLO=1 <-- Enable DAOS NLO encryption
Update the On-disk structure (ODS):
Attachment consolidation works for all databases that are on-disk structure ODS 50 and later. Databases with an earlier ODS do not include the DAOS setting in their advanced properties. To create all newly created databases with ODS 50, enter the following setting in your NOTES.INI file:
After that you you could change the ODS from every database / application to ODS 50 with the compact task:
load compact -c mail\bwieczor.nsf
That will run a compact style task on the users mail file and will change the ODS from a earlier version to the ODS 50.
Attachment consolidation is not limited to mail; it occurs as soon as an attachment is saved in any document of any database on the server where the feature is enabled.
I would recommend to set the transaction logging to: "Check file size when extending the file" but keep in mind that you must then enable also a program document which run compact with the -B in the night. If you wish to enable DAOS with 8.5 please check technote #1381303.
If you set the transaction logging to "Check file size when extending the file" the following will happen during mail routing to the users on that server:
The Router calculates the current size of a mail file from its actual physical size. The calculated physical size includes the unused "white space" in a file that results when a user deletes or archives a message. Domino does not immediately recover this white space. As a result, accumulated white space may account for a large portion of the file size, so that the actual mail file size is considerably larger than the combined size of its stored messages.
The size check occurs only if adding a message requires an increase in the size of the mail file. When quota enforcement is enabled and this option is selected, if a message delivered to the mail file requires an increase in the file size that would result in a quota violation, delivery fails. However, a message is always delivered if there is sufficient white space to accommodate it.
Optimum Minimum Size For Participation
By default, the minimum size setting for an attachment to make use of DAOS is 4096 bytes (or 64000 (64K) in later versions). I would recommend using10485760(10 MB) in this field. BUT to find the best option you could use the DAOS Estimator. If you use for example 64000 (64K) then every small jpg picture from every email is collected in your DAOS folder, which can result in a large amount of files and therefore in bad server performance.