As you can see in the following log, the option "--no-compression" does not appear to have any effect. ``` sverbuecheln@seclinux:~$ duplicity full --use-agent --progress --encrypt-sign-key FF6DF532 --exclude ~/.local/share/gnome-boxes/ --exclude ~/.cache/ ~/ file:///mnt/backup/sverbuecheln/ Local and Remote metadata are synchronized, no sync needed. Last full backup date: Tue Mar 14 15:12:54 2023 2.1GB 00:01:00 [45.1MB/s] [========================================>] 100% ETA 0sec --------------[ Backup Statistics ]-------------- StartTime 1678803269.35 (Tue Mar 14 15:14:29 2023) EndTime 1678803327.40 (Tue Mar 14 15:15:27 2023) ElapsedTime 58.05 (58.05 seconds) SourceFiles 3126 SourceFileSize 2874763797 (2.68 GB) NewFiles 3126 NewFileSize 2874763797 (2.68 GB) DeletedFiles 0 ChangedFiles 0 ChangedFileSize 0 (0 bytes) ChangedDeltaSize 0 (0 bytes) DeltaEntries 3126 RawDeltaSize 2871461489 (2.67 GB) TotalDestinationSizeChange 2234994603 (2.08 GB) Errors 0 ------------------------------------------------- sverbuecheln@seclinux:~$ duplicity full --use-agent --progress --encrypt-sign-key FF6DF532 --exclude ~/.local/share/gnome-boxes/ --exclude ~/.cache/ --no-compression ~/ file:///mnt/backup/sverbuecheln/ Local and Remote metadata are synchronized, no sync needed. Last full backup date: Tue Mar 14 15:14:29 2023 2.1GB 00:01:00 [39.1MB/s] [========================================>] 100% ETA 0sec --------------[ Backup Statistics ]-------------- StartTime 1678803345.08 (Tue Mar 14 15:15:45 2023) EndTime 1678803402.79 (Tue Mar 14 15:16:42 2023) ElapsedTime 57.71 (57.71 seconds) SourceFiles 3126 SourceFileSize 2874763797 (2.68 GB) NewFiles 3126 NewFileSize 2874763797 (2.68 GB) DeletedFiles 0 ChangedFiles 0 ChangedFileSize 0 (0 bytes) ChangedDeltaSize 0 (0 bytes) DeltaEntries 3126 RawDeltaSize 2871461489 (2.67 GB) TotalDestinationSizeChange 2234998399 (2.08 GB) Errors 0 ------------------------------------------------- ``` However, the corresponding GnuPG option actually disables compression and has a significant effect on performance, 5x speedup in this example. ``` sverbuecheln@seclinux:~$ duplicity full --use-agent --progress --encrypt-sign-key FF6DF532 --exclude ~/.local/share/gnome-boxes/ --exclude ~/.cache/ --gpg-options "--compress-algo none" ~/ file:///mnt/backup/sverbuecheln/ Local and Remote metadata are synchronized, no sync needed. Last full backup date: Tue Mar 14 15:15:44 2023 2.7GB 00:00:15 [151.9MB/s] [========================================>] 100% ETA 0sec --------------[ Backup Statistics ]-------------- StartTime 1678803509.55 (Tue Mar 14 15:18:29 2023) EndTime 1678803522.31 (Tue Mar 14 15:18:42 2023) ElapsedTime 12.76 (12.76 seconds) SourceFiles 3126 SourceFileSize 2874763797 (2.68 GB) NewFiles 3126 NewFileSize 2874763797 (2.68 GB) DeletedFiles 0 ChangedFiles 0 ChangedFileSize 0 (0 bytes) ChangedDeltaSize 0 (0 bytes) DeltaEntries 3126 RawDeltaSize 2871461489 (2.67 GB) TotalDestinationSizeChange 2898697176 (2.70 GB) Errors 0 ------------------------------------------------- ``` If not specified by command line option, GnuPG will select the preferred compression algorithm from the PGP key. This makes sense for e-mails, but not so much for backups. In many cases, compression does not gain much because the large files are usually pictures, audio and video. The performance cost is not worth it. So my suggestion would be that the --no-compression option disables GnuPG compression.