How to create a warning, based on the file size?

Hello, I need to know the size of a file after the compression and receive an email with a warning if the size is above a specified size.

Hello and welcome!

I assume you’re talking about the files that Duplicati generates. The maximum size should be the “remote volume size” that is shown on page 5 of the backup configuration. The default is 50MiB.

Yes, I’m talking about the files that duplicate generates, I’ll test this configuration, thank you.

Features and How the backup process works say more, but in short, individual files aren’t just compressed then backed up. A second identical file takes no extra size for file data storage. Question needs clarification.

I want to know, the size of a backup file, before I upload to my back end server.

It will be limited to the configured remote volume size, regardless of source file size.
Having a warning in this situation makes no sense. Size tuning is possible though…

Choosing sizes in Duplicati

EDIT:

The size here is for a dblock file which contains blocks of source files. It is theoretically possible to also create a large dlist file because each path is listed along with information on how to go about restoring. There is no size control on this, but you can keep an eye on its size as your backup file list gets longer…