I was doing a test restore this evening from a WebDAV backup, and I noticed that during the restoration process the temporary directory was filling up with all of the files that Duplicati was downloading. This was the current stable version, 2.3.0.4.
I have noticed that it’s not that Duplicati never deletes any of the temporary files, but rather it keeps them around for quite a long time. You can occasionally see the number of files tick downward by small amounts, but the growth outruns it considerably.
For fun, I updated from 2.3.0.4 Stable to 2.3.1.0 Beta, but the problem still exists there as well.
For this particular test restore, the files that are being restored are some Hyper-V .VHDX files, and so they are quite large at several hundred GB each.
I noticed that this problem doesn’t exist when using the “Legacy Restore” method.
If this is just how the non-Legacy restore works, and Duplicati needs to keep the temporary files around for longer when using this method, then I will need to make sure that I use the legacy path for restorations with large files.