Backup of Attachments and Files

In general, this plugin backups two types of information:

Objects
Files.

Objects are elements representing some item in Exchange such as a calendar event, a contact, an email, etc., while files are attachments of those items.

While objects are directly streamed from memory to the backup engine, files need to be downloaded to the FD host before being sent. This is done in order to perform metadata checks and to improve overall performance, as this the way operations can be parallelized. Every file is removed just after being completely downloaded and sent to the backup engine.

The path used for this purpose is established by the path plugin variable, that usually is set up in the backend script (e2ws_backend) with the value: /opt/bacula/working.

Inside the path variable, a spool directory will be created and used for those temporary download processes.

Therefore, it is necessary to have at least enough disk space available for the size of the largest file in the backup session. If you are using concurrency between jobs, or through the same job (by default this is the case through the concurrent_threads=5 parameter), you would need at least that size for the largest file multiplied by the number of operations you run in parallel.