scheduled mirror deletes backup on drive failure

[eikefriedrich]

I've recently moved to FreeFileSync from batch robocopy jobs because FFS has a GUI and has options like shadow copy. FFS is great, but I have noticed a behaviour which defeats my backup.

I am running FFS on a single machine which mirrors a number of folders from network shares to a local backup drive, e.g. a number of folder pairs with \\network\share1 on the left and D:\backup\share1 on the right. This mirror works fine, unless the left folder does not exist (e.g. it has failed or the network has gone down). In this case I am informed that the folder \\network\share1 does not exist and if I continue it will be considered empty. If I continue the contents of the right folder are deleted (because the mirror source is considered to be empty). If I don't continue then the other folder pairs are not backed up.
The result is that if the network drive fails, then when the next batch job runs the backup will be deleted. I would expect that if the source folder no longer exists then nothing would be done to the destination folder, ie the root source folder be treated differently to the subfolders.

Ideally I would like the job to continue on errors, but if the root source of a folder pair does not exist then the target is not deleted. I currently have the mirror customised so that it does not delete anything on the target, but this will lead to a backup that grows too fast. Am I missing a principle of operation here, can anyone suggest a workaround?

[Zenju]

If you are using the most recent version of FFS, temporary network drops are covered, and never lead to data loss.

[eikefriedrich]

If you are using the most recent version of FFS, temporary network drops are covered, and never lead to data loss.

My apologies and thank you for the swift response.
On trying to replicate this I can see what I have missed: I was trying to emulate the batch job by running the job in the GUI first. When I ran a Compare against a left folder which had been disconnected the GUI presents the message that if I continue the source folder will be considered empty, then presents an alarming list of files that will be deleted on the right side.
If I actually run this Synchronisation job then again the confirmation dialogue shows that all the destination files will be deleted, but the job itself fails with a fatal error because the source file cannot be found. The batch job then continues to the next folder. Previously I was not brave enough to continue and risk deletion, but this situation has clearly been considered, I just found the GUI information rather alarming.