I’ve got an HDD attached to my router at home I can access over FTP or SMB.
Is there a way to backup drives like that over lan by setting them up as a source in Duplicati?
If you can get the remote drive to appear as a local drive (such as mapping it to a drive letter or mounting it as a subfolder of a local drive) then, the yes - you can back it up.
But you won’t be getting the best performance that way. Remember, to back something up Duplicati has to read the entire file contents (at least for the first backup) so you’ll essentially be transferring the entire remote source across your connection so Duplicati can back it up.
On future backup Duplicati will just check file size / timestamps - but if they differ, then it will again have to transfer that entire file from the remote drive so it can scan through and figure out what part(s) of the file have changed and need to be backed up.
Note that if a backup runs and the remote drive is not available, then depending on how you have it mounted / mapped then Duplicati with either fail the backup run OR declare the remote contend “deleted” and flag it as such in the backup.
On later runs if the remote drive becomes available again the content will be considered “un-deleted” and, assuming no size / timestamp changes, not require much transfer.
This could case odd looking restore scenarios where one backup version has the files you want while then next doesn’t.
So yes - it can work, but you have to be careful when setting it up and know about the potential pitfalls.
I’ve got mostly media files stored on an external USB drive which is connected as a network share to my Plex server. There’s maybe two or three DVR recording that get added throughout the week. Otherwise the data is pretty much “cold storage” that doesn’t get touched again.
I just would like to back those files up to a second network share of identical size.
Would it be a practical solution to hook both drives up to the machine running Duplicati, run the backup job once and after that’s done only backup the added media files over the network? Instead of running the entire backup over the network?
That’s not going to get you very much unless the paths to the local drives are the same as they are for the shared ones. This is because when a path changes Duplicati considers the file at the new path to be, well, new and thus needing full hashing to check for pre-existing blocks.
Since all the blocks for the files will have already been saved to the backup when the drive was local Duplicati won’t actually store the flie contents again but it will still need to pull it all over the network so it can be hashed.
Since it sounds like this is all local your best be is probably to just run it over the network from the start. Unless you’ve got a slow LAN it shouldn’t cause any problems other than taking longer than you feel it should. And with the files being mostly cold storage after that first backup I doubt you’ll have much issues.
Once thing you might want to consider is to set up the “final” version of the backup using the network share as a source but only choose one file or one folder of your set just to see what performance is like. If it works for you then you can either slowly add more or just add all the rest in all at once.
I, and others, have used this method as a way to get used to Duplicati and fine-tune settings without having to way for an entire full backup to finish only to realize we had something set wrong. 