Backup considerations for DAOS

In a standard Notes® database (NSF), the attachments are stored inside of the NSF file itself, and the database is self-contained. In order to back up a standard Notes database, only the NSF file itself needs to be backed up. After you introduce DAOS, the NSFs that participate in DAOS contain only references to the NLO files where the attachment content is stored. As a result, backing up the NSF alone is no longer enough. The NLO data needs to be backed up as well.

When performing standard NSF backups, there are two main approaches. The individual NSF being backed up can be taken offline (or the entire server can be stopped) so that no changes occur to the NSF over the duration of the backup operation. The other method allows the NSF and server to remain active, but requires using a backup utility program that interacts with the Domino® backup/restore API. Using a utility ensures that a consistent copy of the NSF contents is recorded, despite any changes that occur to the NSF over the duration of the backup operation. If you are using a backup utility that does not use the backup/restore API, you must stop the Domino server and all Domino-related applications for the duration of the backup.

None of the processing for NSF backups needs to change for DAOS. The change needed to accommodate DAOS is simply a procedural addition: in addition to backing up the NSF data, you must also back up the NLO data.

Backing up the NLO files in the DAOS repository can be done either while the Domino server is down, or when it is up and running. The backup does not require the use of any Domino API-based utilities. Once NLO files are written initially, Domino never modifies their contents, so the backup mechanism does not have to work around file-write activity. NLO files can be backed up as any other generic file on the file system. Only the NLO files that are complete and not in the process of being written to or renamed need to be backed up. Any that are busy can be skipped until the next backup. Most backup applications will automatically skip files that they can not read because of other activity.